The theoretical yield of Li3N is 1.24 mol or 138.16 g. The percent yield of the reaction is 4.23%.
Explanation:To find the theoretical yield of Li3N, we first need to determine the limiting reactant. This is done by comparing the moles of each reactant to the stoichiometric ratio of the balanced equation. The molar mass of Li is 6.94 g/mol and the molar mass of N2 is 28.02 g/mol. First, convert the given masses of Li and N2 to moles using their respective molar masses:
12.7 g Li X (1 mol Li / 6.94 g Li) = 1.83 mol Li
34.7 g N2 X (1 mol N2 / 28.02 g N2) = 1.24 mol N2
Then, divide the number of moles of each reactant by its stoichiometric coefficient to find the mole ratio:
1.83 mol Li / 6 = 0.305 mol Li3N
1.24 mol N2 / 1 = 1.24 mol Li3N
Since N2 gives a smaller value, it is the limiting reactant. Therefore, the theoretical yield of Li3N is 1.24 mol or 138.16 g.
To calculate the percent yield, divide the actual yield by the theoretical yield, then multiply by 100:
Percent yield = (Actual yield / Theoretical yield) X 100
Percent yield = (5.85 g / 138.16 g) X 100 = 4.23%
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Hydrogen peroxide decomposes to water and oxygen at constant pressure by the following reaction: 2H2O2(l) → 2H2O(l) + O2(g) ΔH = -196 kJ Calculate the value of q (kJ) in this exothermic reaction when 2.50 g of hydrogen peroxide decomposes at constant pressure.
In this exothermic reaction, 2.50 g of hydrogen peroxide decomposes and generates -7.22 kJ of heat, as indicated by the negative sign.
Explanation:The question asks for the amount of heat (q) generated when 2.50 g of hydrogen peroxide decomposes at constant pressure to give water and oxygen. Given that the enthalpy change (ΔH) for the reaction 2H2O2(l) → 2H2O(l) + O2(g) is -196 kJ, it indicates that the decomposition of hydrogen peroxide is an exothermic reaction and heat is released in the process. The negative sign of ΔH confirms this.
Firstly, we will have to find out how many moles of H2O2 are there in 2.5 g. Using the molar mass of H2O2 (34 g/mol), we get about 0.074 moles of H2O2. In the balanced chemical equation, 2 moles of hydrogen peroxide generates -196 kJ of heat. Therefore, for 0.074 moles, we calculate it by (-196 kJ * 0.074)/2 = -7.22 kJ.
The <-strong>value of q in this exothermic reaction when 2.50 g of hydrogen peroxide decomposes at constant pressure is therefore -7.22 kJ. The negative sign indicates heat is being released, or in other words, the reaction is exothermic.
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The value of q, representing the thermal energy transferred in the decomposition of 2.50g of hydrogen peroxide at constant pressure, is approximately -7.16 kJ.
Explanation:The question asks for the value of q, which represents the thermal energy transferred during a reaction, in an exothermic reaction where 2.50 g of hydrogen peroxide decomposes into water and oxygen gas. In this given case, we know the enthalpy change (∆H) of the reaction is -196 kJ, indicating that this is an exothermic process where that much energy is being released to the surroundings.
We know from the balanced chemical equation 2H2O2(l) → 2H2O(l) + O2(g) that 2 moles of H2O2 decompose to release ∆H amount of energy. Let's find out the number of moles in 2.50 g of H2O2. The molar mass of H2O2 is approximately 34.01 g/mol. So, the number of moles = mass/molar mass = 2.50 g / 34.01 g/mol = 0.0735 moles.
Considering the stoichiometry of the reaction, ∆H of -196 kJ is associated with 2 moles of H2O2. Therefore, the energy associated with 0.0735 mol will be:
q ( energy ) = ∆H x (moles of H2O2 /2) = -196 kJ x (0.0735 mol / 2 mol) = -7.1625 kJ
Therefore, the quantity of thermal energy (q) released in this decomposition reaction is approximately -7.16 kJ.
Learn more about Thermal Energy in Chemical ReactionA 0.50 M solution of an unknown acid has a pH = 4.0. Of the following, which is the acid in the solution?
HOCl (Ka = 2.0 x 10-8)
HBr (strong acid)
HF (Ka = 6.8 x 10-4)
C6H5OH (Ka = 1.0 x 10-10)
Answer:
[tex]HOCl[/tex], [tex]K_a=2.0\times 10^{-8}[/tex]
Explanation:
pH is defined as the negative logarithm of the concentration of hydrogen ions.
Thus,
pH = - log [H⁺]
Strong acids dissociate completely and thus, 0.5 M of a solution of a strong acid yields a pH of 1.0 .
The expression of the pH of the calculation of weak acid is:-
[tex]pH=-log(\sqrt{k_a\times C})[/tex]
Where, C is the concentration = 0.5 M
Given, pH = 4.0
So, for [tex]HOCl[/tex], [tex]K_a=2.0\times 10^{-8}[/tex]
[tex]pH=-log(\sqrt{2.0\times 10^{-8}\times 0.5})[/tex]
pH = 4.0
Hence, the acid is HOCl.
Final answer:
The acid with a 0.50 M solution resulting in a pH of 4.0 is likely hydrofluoric acid (HF), due to its intermediate acid strength indicated by its Ka value of 6.8 x 10^-4.
Explanation:
The question involves determining the identity of an unknown acid based on its molarity and pH balance. A 0.50 M solution of the acid has a pH of 4.0. The pH is a measure of the hydrogen ion concentration in a solution, and the pKa value is the negative logarithm of the acid dissociation constant (Ka), which provides insight into the strength of an acid. Strong acids fully dissociate in water, resulting in a lower pH for a given concentration, while weak acids do not completely dissociate, leading to higher pH values.
Given the pH of 4.0 for a 0.5 M solution, we are looking for an acid with a pKa close to 4, since this would indicate a weak acid that only partially dissociates. Among the given options, HF with a Ka value of 6.8 x 10-4 would likely be the correct acid since it has an adequate strength to result in a pH of 4 for a 0.5 M solution. On the other hand, HBr is a strong acid and would yield a much lower pH for the same concentration, while HOCl and C6H5OH have much lower Ka values, meaning they are weaker acids and would result in a higher pH than 4.
The following reaction is exothermic.
2 S(s) + 3 O2(g) → 2 SO3(g)
What can we say about the spontaneity of this reaction?
(A) spontaneous at all temperatures
(B) spontaneous only at high temperatures
(C) spontaneous only at low temperatures
(D) non spontaneous at all temperatures
(E) more information is need to predict if the reaction is spontaneous
Answer : The correct option is, (C) spontaneous only at low temperatures.
Explanation :
According to Gibb's equation:
[tex]\Delta G=\Delta H-T\Delta S[/tex]
[tex]\Delta G[/tex] = Gibbs free energy
[tex]\Delta H[/tex] = enthalpy change
[tex]\Delta S[/tex] = entropy change
T = temperature in Kelvin
As we know that:
[tex]\Delta G[/tex]= +ve, reaction is non spontaneous
[tex]\Delta G[/tex]= -ve, reaction is spontaneous
[tex]\Delta G[/tex]= 0, reaction is in equilibrium
The given chemical reaction is:
[tex]2S(s)+3O_2(g)\rightarrow 2SO_3(g)[/tex]
As we are given that, the given reaction is exothermic that means the enthalpy change is negative.
In this reaction, the randomness of reactant molecules are more and as we move towards the formation of product the randomness become less that means the degree of disorderedness decreases. So, the entropy will also decreases that means the change in entropy is negative.
Now we have to determine the spontaneity of this reaction when ΔH is negative and ΔS is negative.
As, [tex]\Delta G=\Delta H-T\Delta S[/tex]
[tex]\Delta G=(-ve)-T(-ve)[/tex]
[tex]\Delta G=(+ve)[/tex] (at high temperature) (non-spontaneous)
[tex]\Delta G=(-ve)[/tex] (at low temperature) (spontaneous)
Thus, the reaction is spontaneous only at low temperatures.
Which of the following statements is true regarding sodium and chlorine?A.) Sodium has greater electronegativity and a larger first ionization energyB.) Sodium has a larger first ionization energy and a larger atomic radiusC.) Chlorine has a larger atomic radius and greater electronegativityD.) Chlorine has greater electronegativity and a larger first ionization energy
Answer:
D.) Chlorine has greater electronegativity and a larger first ionization energy
Explanation:
first we have to consider where sodium and chlorine are in the atomic table. Both are in the third row and both are nearly opposite ends of third row. sodium have high tendency to lose an electron while chlorine have higher tendency to gain an electron. so because of this fact chlorine is more electronegative than sodium.
As we move left to right in the periodic table, there is increase in the number of protons in atom and therefore there is increase in attraction between the nucleus and electrons and shrinking down the atom which is general trend when we move from left to right in the periodic table. so chlorine will be smaller than sodium because of the shrinking of the atom and smaller atoms have higher ionization energy because their electrons are close to the nucleus. They require more energy to remove. so this will make chlorine have both a smaller atomic radius and larger ionization energy. so D is the right answer.
Final answer:
The correct statement regarding sodium and chlorine is that chlorine has a larger atomic radius and greater electronegativity.
Explanation:
The correct statement regarding sodium and chlorine is Option C: Chlorine has a larger atomic radius and greater electronegativity.
Chlorine, with 17 electrons, has a strong attraction for electrons and tends to gain an electron to form a chloride ion (Cl-). Sodium, with 11 electrons, has a lower ionization potential and tends to lose an electron to form a sodium ion (Na+). Therefore, chlorine has a greater electronegativity and a larger atomic radius compared to sodium.
Additionally, when sodium and chlorine react, sodium donates an electron to chlorine, forming an ionic bond and creating the compound sodium chloride (NaCl).
The solubility product of PbI2 is 7.9x10^-9. What is the molar solubility of PbI2 in distilled water?
A.) 2.0x10^-3
B.) 1.25x10-3
C.) 5.0x10^-4
D.) 8.9x10^-5
Answer:
The molar solubility of distilled water is [tex]$1.25 \times 10-3$[/tex] (Option B)
Explanation:
Given:
[tex]Pbl_2 -7.9 \times 10^-^9.[/tex]
Expression for solubility constant is,
[tex]$K_{s p}=\left[P b^{2+}\right]\left[I^{-}\right]^{2}$[/tex]
The given equation is,
[tex]$K_{s p}=7.9 \times 10^{-9}$[/tex]
Equation is to calculated as,
[tex]$7.9 \times 10^{-9}=(s) \times(2 s)^{2}$[/tex]
[tex]$7.9 \times 10^{-9}=4 s^{3}$[/tex]
[tex]$s=1.25 \times 10^{-3} \mathrm{~mol} / L$[/tex]
The solubility product in distilled water is [tex]$s=1.25 \times 10^{-3} \mathrm{~mol} / L$[/tex].
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https://brainly.com/question/819068The correct answer is C.)[tex]5.0x10^-^4.[/tex]
To determine the molar solubility of PbI2 in distilled water, we need to use the solubility product constant (Ksp) for PbI2, which is given as 7.9x10^-9.
The chemical equation for the dissociation of PbI2 in water is:
[tex]\[ PbI_2(s) \rightleftharpoons Pb^{2+}(aq) + 2I^-(aq) \][/tex]
The solubility product expression for this equilibrium is:
[tex]\[ Ksp = [Pb^{2+}][I^-]^2 \][/tex]
Let's denote the molar solubility of PbI2 as s. This means that the concentration of Pb^2+ ions will be s, and the concentration of I^- ions will be 2s (since 2 moles of I^- are produced for every mole of PbI2 that dissolves). We can now express the Ksp equation in terms of s:
[tex]\[ Ksp = s \cdot (2s)^2 \][/tex]
[tex]\[ Ksp = s \cdot 4s^2 \][/tex]
[tex]\[ Ksp = 4s^3 \][/tex]
Now we can solve for s using the given Ksp value:
[tex]\[ 7.9 \times 10^{-9} = 4s^3 \][/tex]
[tex]\[ s^3 = \frac{7.9 \times 10^{-9}}{4} \][/tex]
[tex]\[ s^3 = 1.975 \times 10^{-9} \][/tex]
[tex]\[ s = \sqrt[3]{1.975 \times 10^{-9}} \][/tex]
[tex]\[ s \approx 5.82 \times 10^{-4} \][/tex]
Since we are looking for the molar solubility, we can round this value to the appropriate number of significant figures, which is two significant figures based on the Ksp value given [tex](7.9x10^-9[/tex] has two significant figures). Therefore, the molar solubility of PbI2 in distilled water is approximately:
[tex]\[ s \approx 5.8 \times 10^{-4} \][/tex]
The closest answer choice to this calculated value is C.) 5.0x10^-4.
The freezing point of a 1.00 molal aqueous solution of calcium chloride (CaCl2) is lower than the freezing point of a 1.00 molal aqueous solution of ethylene glycol (C2H6O2). Why are the freezing points of the two solutions different?
Answer:
The calcium chloride is an electrolyte salt, so the frezzing point of solution must be higher than ethylene glycol.
Explanation:
This is the colligative property for this question: Frezzing point depression
ΔTf = Kf · molal · i
ΔTf = T° fussion solvent pure - T° fussion solution
As both solutions are the same in molality and the solvent is water, the formula stands the same but the Calcium Chloride is a salt which is dissociated in water like this:
CaCl₂ → Ca²⁺ + 2Cl⁻
We have 3 moles of ions, so this value modiffy the formula with the Van't Hoff Factor (number of ion particles per individual molecule of solute).
Ethyleneglycol is a non-electrolytic organic compound (It is often used 1 as the i).
Let's see the formula in both:
0° - T° fussion solution = Kf · molal · 3 → CaCl2
0° - T° fussion solution = Kf · molal · 1 → C2H6O2
For which of these processes is the value of ΔH expected to be negative?
I. The temperature (of water) increases when calcium chloride dissolves in water
II. Steam condenses to liquid water
III. Water freezes
IV. Dry ice sublimes
A.) IV only
B.) I, II, and III
C.) I only
D.) II and III only
The value of ΔH is expected to be negative in processes where heat is released, which includes the condensation of steam to liquid water (II) and the freezing of water (III), both exothermic processes. Therefore, the correct answer is option D.) II and III only.
Explanation:The question asks for which processes the value of ΔH (enthalpy change) is expected to be negative, indicating an exothermic reaction where heat is released. We can analyze each process one by one:
I. When calcium chloride dissolves in water and the temperature increases, this process is exothermic. However, it indicates that heat is being released due to the dissolution, not the enthalpy change of water itself.II. When steam condenses to liquid water, it is an exothermic process as it releases heat.III. When water freezes, heat is released during the phase transition from liquid to solid, thus it is also an exothermic process.IV. Sublimation of dry ice is an endothermic process because it requires heat to transition from solid to gas.Therefore, the processes where ΔH is expected to be negative (exothermic) are options II and III, where steam condenses and water freezes.
How many total moles of ions are released when 0.0859 mol of Rb2SO4 dissolves completely in water?
0.2577 moles of ions
Explanation:
The dissociation of Rb₂SO₄ in water:
Rb₂SO₄ (s) + H₂O (l) → 2 Rb²⁺ (aq) + SO₄²⁻ (aq)
where:
(s) - solid
(l) - liquid
(aq) - aqueous
(aq) - aqueous
Knowing the dissociation of Rb₂SO₄ in water, we devise the following reasoning:
if 1 mol of Rb₂SO₄ dissociate in 2 moles of Rb²⁺ and 1 mole of SO₄²⁻
then 0.0859 moles of Rb₂SO₄ dissociate in X moles of Rb²⁺ and Y moles of SO₄²⁻
X = (0.0859 × 2) / 1 = 0.1718 moles of Rb²⁺
Y = (0.0859 × 1) / 1 = 0.0859 moles of SO₄²⁻
total moles of ions = moles of Rb²⁺ ions + moles of SO₄²⁻ ions
total moles of ions = 0.1718 + 0.0859 = 0.2577 moles
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Total moles of ions released when 0.0859 mol of Rb2SO4 dissolves completely in water are 0.2577 mol.
What are moles?In the International System of Units, Mole is the base unit of the amount of any substance.
The dissociation of [tex]Rb_2SO_4[/tex] in water:
[tex]\rm Rb_2SO_4 (s) + H_2O (l) = 2 Rb^2^+ (aq) + SO_4^\;^2^- (aq)[/tex]
If 1 mol of [tex]Rb_2SO_4[/tex] dissociating into 2 moles of Rb²⁺ and 1 mole of SO₄²⁻
Then, 0.0859 mol of [tex]Rb_2SO_4[/tex] will dissociate into?
[tex]X = \dfrac{(0.0859 \times 2) }{1 } = 0.1718 moles\; of\; Rb^2^+[/tex]
[tex]Y= \dfrac{(0.0859 \times 2) }{1 } = 0.0859\; moles\; of\; So_4\;^2^-[/tex]
Total moles of ions = moles of Rb²⁺ ions + moles of SO₄²⁻ ions
Total moles of ions = 0.1718 + 0.0859 = 0.2577 moles
Thus, the moles of ions are 0.2577 mol.
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During an exothermic chemical reaction,
A. a system becomes warmer, and the chemical substances undergo a decrease in potential energy.
B. a system becomes warmer, and the chemical substances undergo an increase in potential energy.
C. a system becomes cooler, and the chemical substances undergo a decrease in potential energy.
D. a system becomes cooler, and the chemical substances undergo an increase in potential energy.
E. a system becomes warmer, and additional heat is gained from the surroundings.
An exothermic chemical reaction occurs when a system becomes warmer and the potential energy of the chemical substances increases.
What is Exothermic chemical reaction?An exothermic reaction is one in which energy is released in the form of light or heat. Thus, in an exothermic reaction, energy is transferred into the surroundings rather than taken from the surroundings as in an endothermic reaction. The change in enthalpy ( ΔH ) in an exothermic reaction is negative. Exothermic reactions characterise all combustion reactions. A substance burns as it combines with oxygen during a combustion reaction. When substances burn, they typically emit energy in the form of heat and light. Wood combustion is an exothermic reaction that releases a lot of energy in the form of heat and light.The net amount of energy required to start an exothermic reaction is less than the net amount of energy released by the reaction. The net amount of heat energy that flows through a calorimeter, a device used to measure the heat released by a chemical reaction, is equal to the negative of the total energy change of the system. The absolute total of energy in a given chemical system is extremely difficult to measure or even calculate. As a result, the energy change (or enthalpy change, denoted by ΔH) is used instead. The following equation describes the relationship between the value of ΔH and the reaction's bond energies.ΔH = (energy used in the bond formation that yields products) – (energy released when the reactant bonds are broken)To learn more about exothermic chemical reaction refer :
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Final answer:
The correct answer is A, wherein during an exothermic reaction, the system warms up due to a decrease in potential energy of the substances involved.
Explanation:
The correct answer to this question is option A: a system becomes warmer, and the chemical substances undergo a decrease in potential energy. During an exothermic chemical reaction, energy is released into the surroundings in the form of heat, causing the temperature of the surrounding system to increase. This energy release is due to the reactants possessing higher potential energy than the products; as the reaction occurs, the potential energy stored within the chemical bonds of the reactants is converted into kinetic energy (heat), significantly reducing the potential energy within the resulting products. This principle is foundational in understanding energy changes during chemical reactions, which is crucial in fields ranging from chemical engineering to environmental science.
The mass of a proton is 1.00728 amu andthat of a neutron is 1.00867 amu. What is the binding energy pernucleon (in J) of a Co nucleus? (The mass of a cobalt-60 nucleus is59.9338 amu.) a. 3.039× 10^-12 b. 2.487 × 10^-12 c. 7.009 × 10^-14 d. 1.368 × 10^-12 e. 9.432 × 10^-13
Answer:
The binding energy per nucleon = 1.368*10^-12 (option D)
Explanation:
Step 1: Data given
The mass of a proton is 1.00728 amu
The mass of a neutron is 1.00867 amu
The mass of a cobalt-60 nucleus is59.9338 amu
Step 2: Calculate binding energy
The mass defect = the difference between the mass of a nucleus and the total mass of its constituent particles.
Cobalt60 has 27 protons and 33 neutrons.
The mass of 27 protons = 27*1.00728 u = 27.19656 u
The mass of 33 neutrons = 33*1.00867 u = 33.28611 u
Total mass of protons + neutrons = 27.19656 u + 33.28611 u = 60.48267 u
Mass of a cobalt60 nucleus = 59.9338 amu
Mass defect = Δm = 0.54887 u
ΔE =c²*Δm
ΔE = (3.00 *10^8 m/s)² *(0.54887 amu))*(1.00 g/ 6.02 *10^23 amu)*(1kg/1000g)
Step 3: Calculate binding energy per nucleon
ΔE = 8.21 * 10^-11 J
8.21* 10^-11 J / 59.9338 = 1.368 *10^-12
The binding energy per nucleon = 1.368*10^-12 (option D)
To calculate the binding energy per nucleon of a Co nucleus, we calculate the mass defect, use Einstein's equation to calculate the binding energy, and then divide by the number of nucleons in the nucleus. The binding energy per nucleon can be converted to MeV using a conversion factor.
Explanation:To calculate the binding energy per nucleon (in J) of a Co nucleus, we first need to determine the total binding energy. The mass defect for a Co nucleus is the difference between the total mass of the nucleus and the sum of the masses of the individual protons and neutrons. The mass defect can be calculated by subtracting the actual mass of the Co nucleus (59.9338 amu) from the sum of the individual masses of protons (1.00728 amu) and neutrons (1.00867 amu). Once we have the mass defect, we can use Einstein's equation E=mc² to calculate the binding energy. Finally, to find the binding energy per nucleon, we divide the total binding energy by the number of nucleons in the nucleus.
Using the given values, we have:
Mass defect (Δm) = (59.9338 amu) - (27 * 1.00728 amu + 33 * 1.00867 amu)
Binding energy (E) = Δm * (c²) = Δm * (3 × 10^8 m/s)²
Binding energy per nucleon = E / number of nucleons in Co nucleus
Substituting the values and performing the calculations, we get the binding energy per nucleon in joules. We can then convert the binding energy per nucleon from joules to MeV by using the conversion factor, 1 MeV = 1.602 × 10^-13 J.
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Which of the following describes a system that CANNOT be thermodynamically favored?
A.) ΔS is negative and ΔH is positive
B.) ΔS is positive and ΔH is positive
C.) ΔS is negative and ΔH is negative
D.) ΔS is positive and ΔH is negative
Answer: d) ΔS is positive and ΔH is negative
Explanation:
According to Gibb's equation:
[tex]\Delta G=\Delta H-T\Delta S[/tex]
[tex]\Delta G[/tex] = Gibbs free energy
[tex]\Delta H[/tex] = enthalpy change
[tex]\Delta S[/tex] = entropy change
T = temperature in Kelvin
[tex]\Delta G[/tex]= +ve, reaction is non spontaneous
[tex]\Delta G[/tex]= -ve, reaction is spontaneous
[tex]\Delta G[/tex]= 0, reaction is in equilibrium
a) ΔS is negative and ΔH is positive
[tex]\Delta G=(-ve)-T(+ve)[/tex]
[tex]\Delta G=(-ve)(-ve)=-ve[/tex]
Reaction is spontaneous at all temperatures.
b) ΔS is positive and ΔH is positive
[tex]\Delta G=(+ve)-T(+ve)[/tex]
[tex]\Delta G=(+ve)(-ve)=-ve[/tex]
Reaction is spontaneous at high temperatures.
c) ΔS is negative and ΔH is negative
[tex]\Delta G=(-ve)-T(-ve)[/tex]
[tex]\Delta G=(-ve)(+ve)=-ve[/tex]
Reaction is spontaneous at low temperatures.
d) ΔS is positive and ΔH is negative
[tex]\Delta G=(+ve)-T(-ve)[/tex]
[tex]\Delta G=(+ve)(+ve)=+ve[/tex]
Reaction is non spontaneous or thermodynamically unfavored at all temperatures.
A mixture of nitrogen and hydrogen gases, at a total pressure of 663 mm Hg, contains 3.46 grams of nitrogen and 0.156 grams of hydrogen. What is the partial pressure of each gas in the mixture? PN2 = mm Hg PH2 = mm Hg
Answer: The partial pressure of nitrogen gas is 405.76 mmHg and that of hydrogen gas is 257.24 mmHg
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
For nitrogen gas:Given mass of nitrogen gas = 3.46 g
Molar mass of nitrogen gas = 28 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of nitrogen gas}=\frac{3.46g}{28g/mol}=0.123mol[/tex]
For hydrogen gas:Given mass of hydrogen gas = 0.156 g
Molar mass of hydrogen gas = 2 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of hydrogen gas}=\frac{0.156g}{2g/mol}=0.078mol[/tex]
Mole fraction of a gas is calculated by using the formula:
[tex]\chi_{A}=\frac{n_{A}}{n_{A}+n_{B}}[/tex] ......(1)
For nitrogen gas:Putting values in equation 1, we get:
[tex]\chi_{\text{nitrogen gas}}=\frac{0.123}{0.123+0.078}=0.612[/tex]
For hydrogen gas:Putting values in equation 1, we get:
[tex]\chi_{\text{hydrogen gas}}=\frac{0.078}{0.123+0.078}=0.388[/tex]
The partial pressure of a gas is given by Raoult's law, which is:
[tex]p_A=p_T\times \chi_A[/tex] ......(2)
where,
[tex]p_A[/tex] = partial pressure of substance A
[tex]p_T[/tex] = total pressure = 663 mmHg
[tex]\chi_A[/tex] = mole fraction of substance A
For nitrogen gas:[tex]p_{\text{Nitrogen gas}}=663mmHg\times 0.612\\\\p_{\text{Nitrogen gas}}=405.76mmHg[/tex]
For hydrogen gas:[tex]p_{\text{Hydrogen gas}}=663mmHg\times 0.388\\\\p_{\text{Hydrogen gas}}=257.24mmHg[/tex]
Hence, the partial pressure of nitrogen gas is 405.76 mmHg and that of hydrogen gas is 257.24 mmHg
Atoms of Mg combine with atoms of F to form a compound. Atoms of which of the following elements combine with atoms of F in the same ratio?
Al
Li
Cl
Ba
Answer:
Ba
Explanation:
Magnesium is the element of second group and third period. The electronic configuration of magnesium is - 2, 8, 2 or [tex]1s^22s^22p^63s^2[/tex]
There are 2 valence electrons of magnesium.
Fluorine is the element of seventeenth group and second period. The electronic configuration of fluorine is - 2, 7 or [tex]1s^22s^22p^5[/tex]
There is 1 valence electron of fluorine.
They will combine and form [tex]MgF_2[/tex]
The same type of compound is formed by the other members of the group 2 since they will have 2 valence electron.
Group 2 includes:- beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).
Hence, correct options is:- Ba
The atom that will combine with F in the same ratio as it combines with Mg is Ba.
We must recall that F combines with atoms of elements group 2 to form ionic compounds of the sort MX2 where M is the metal.
Mg and Ba all belong to group 2 hence they will form compounds with F in the ratio of 1:2
Therefore, the atom that will combine with F in the same ratio as it combines with Mg is Ba.
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When 0.103 g of Zn (s) is combined with enough HCl to make 50.0 mL of solution in a coffee cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.5 degree C to 23.7 degree C. Find Delta H_rxn per mole of Zn. (Use 1.02 glmL for the density of the solution and 4.18 J/g degree C for the specific heat capacity.)
Zn (s) + 2 HCl (aq) rightarrow ZnCl_2 (aq) + H_2 (g)
Delta H_rxn/mol Zn = ____kJ/mol.
First, calculate the total heat absorbed by the solution, then divide this value by the number of moles of Zn reacted. The resulting ΔH_rxn is -162.839 kJ/mol.
Explanation:The question asks us to calculate the heat of reaction, or ΔH_rxn, per mole of Zinc (Zn) in the reaction.
First, we calculate the total heat absorbed by the solution using the formula q=mcΔT, where q is the heat absorbed, m is the mass of the solution, c is the specific heat capacity, and ΔT is the change in temperature.
The mass of the solution can be calculated by multiplying the volume of solution by its density, hence m = V . d = 50.0 mL x 1.02 g/mL = 51.0 g. The change in temperature is 23.7°C - 22.5°C = 1.2°C. Therefore, the heat absorbed by the solution, q, can be calculated as q = (51.0 g) * (4.18 J/g°C) * (1.2°C) = 256.536 J.
Then, to find the heat per mole, ΔH_rxn, we divide this value by the number of moles of Zn reacted. The molar mass of Zn is 65.38 g/mol, so 0.103 g is 0.103 g / 65.38 g/mol = 0.001575 mol of Zn. Therefore, ΔH_rxn = (256.536 J) / (0.001575 mol) = -162,839 J/mol = -162.839 kJ/mol. We get a negative value because the reaction is exothermic.
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ΔHrxn per mole of Zn is approximately -162.27 kJ/mol.
To find the enthalpy change (ΔHrxn) per mole of Zn, we need to follow several steps:
Calculate the mass of the solution: The density of the solution is given as 1.02 g/mL for 50.0 mL, so the mass is 1.02 g/mL × 50.0 mL = 51.0 g.Calculate the heat absorbed or released (q) using the formula: q = mass × specific heat capacity × change in temperature.The temperature change is from 22.5 °C to 23.7 °C, so ΔT = 23.7 °C - 22.5 °C = 1.2 °C.Using the specific heat capacity of 4.18 J/g°C, the heat released is: q = 51.0 g × 4.18 J/g°C × 1.2 °C = 255.70 J.Convert the heat absorbed to kJ: 255.70 J × (1 kJ / 1000 J) = 0.2557 kJ.Calculate the moles of Zn: The molar mass of zinc (Zn) = 65.38 g/mol, so moles of Zn = 0.103 g / 65.38 g/mol = 0.001576 moles.Determine ΔHrxn per mole of Zn: ΔHrxn per mole = 0.2557 kJ / 0.001576 moles = 162.27 kJ/mol.Therefore, ΔHrxn per mole of Zn is approximately -162.27 kJ/mol.
Use the Gizmo to answer the following questions.
A. How many electrons are in a neutral atom of lithium? ___________
B. How many neutrons are in an atom of Mg-25? ___________
C. What is the mass number of an atom with 5 protons and 7 neutrons? ________
D. An ion is a charged atom. How many electrons are in O2- ? ___________
E. How many electrons are in Mg2+?
Answer:
a. 3 electrons
b. 13 neutrons
c. 12 mass number
d. 10 electrons
e. 10 electrons
Explanation:
A. For an element , the atomic number of a given element is equal to the number of protons , and
For a neutral atom , the number of electrons equals the number of protons ,
Hence ,
The atomic number of Li = 3 ,
Hence ,
Number of electron for Li = 3 .
B.
Number of neutrons = mass number - atomic number ,
For Mg-25
For Magnesium , atomic number = 12 ,
Number of neutrons = 25 - 12 = 13 neutrons
C. Mass number of an element is equal to the sum of number of protons and number of neutrons ,
Hence , mass number = 5 + 7 = 12 .
D. For a negatively charged ion , add the negative charge value with the number of electrons of the neutral atom ,
For Oxygen , atomic mass = 8 ,
hence , number of electrons = 8
For O²⁻ = 8 + 2 = 10 electrons
E. For a positively charged ion , subtract the positive charge value with the number of electrons of the neutral atom ,
For Magnesium , atomic number = 12 ,
hence , number of electrons = 12 ,
for , Mg²⁺ , number of electrons = 12 - 2 = 10 electrons ,
A neutral atom of Lithium has 3 electrons. Mg-25 has 13 neutrons. An atom with 5 protons and 7 neutrons has a mass number of 12. O2- has 10 electrons and Mg2+ has 10 electrons.
Explanation:A. A neutral atom of lithium contains 3 electrons, equal to its atomic number. B. An atom of Mg-25 has 12 protons (since magnesium's atomic number is 12), and as Mg-25 indicates a mass number of 25, subtracting the atomic number from the mass number gives us 13 neutrons. C. The mass number of an atom is the total number of protons and neutrons in its nucleus. So for an atom with 5 protons and 7 neutrons, the mass number is 12. D. O2- is an ion of oxygen that has gained 2 electrons. Oxygen has 8 electrons in its neutral state so O2- has 10 electrons. E. Mg2+ means that magnesium has lost 2 electrons, so Mg2+ has 10 electrons (since in its neutral state it has 12).
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When 0.485 g of compound X is burned completely in a bomb calorimeter containing 3000 g of water, a temperature rise of 0.285°C is observed. What is ΔU of the reaction for the combustion of compound X? The hardware component of the calorimeter has a heat capacity of 3.81 kJ/°C. The specific heat of water is 4.184 J/g·°C, and the MW of X is 56.0 g/mol.
-538 kJ/mol
4660 kJ/mol
-4660 kJ/mol
538 kJ/mol
Answer:
ΔU = -538kJ/mol
Explanation:
Step 1: Data given
Mass of compound X = 0.485 grams
Mass of water = 3000 grams
Temperature rise = 0.285 °C
Heat capacity of the calorimeter = 3.81 kJ/°C
Specific heat of water = 4.184 J/g°C
MW of X = 56.0 g/mol
Step 2: Calculate q
∆U = ΔH - PΔV
Since the bomb calorimeter has a constant volume ΔV = 0
⇒ ΔU = ΔH
qrxn = - (q(water) + q(bomb))
q(bomb) = 3810 J/°C * 0.285 = 1085.85 J
q(water) = 3000g * 4.184 J/g°C * 0.285°C = 3577.32 J
qrxn = q(water) + q(bomb)
qrxn = 4663.17 J = 4.66 kJ (Since this is an exothermic, the heat is released. (q is positive, ΔH is negative).
Step 3: Calculate moles of compound
Moles = mass / molar mass
Moles = 0.485 grams / 56.0 g/mol
Moles = 0.00866 moles
Step 4: Calculate ΔU
= 4663.17 J /0.00866 moles = 538472 j/mol = 538.5 kJ/mol
Since the reaction is exothermic, ΔU is negative
ΔU = -538kJ/mol
Use the partition function for a harmonic oscillator, q = 1 / (1- e^-hv/kBT) , to determine the ratio of populations in the lowest and first excited energy levels, P0/P1 , for the indicated systems at two temperatures, 50 K and 298 K :
(a) The 1700 cm−1 stretching vibrational mode for the carbonyl (C=O) group in the peptide bond of a polypeptide.
(b) the 150 cm−1 torsional vibrational mode for the C=C bond in trans-2-butadiene.
Answer
The answer and procedures of the exercise are attached in the following archives.
Explanation
You will find the procedures, formulas or necessary explanations in the archive attached below. If you have any question ask and I will aclare your doubts kindly.
Answer:
why a solution is a home generous mixture?
A 23.9 g sample of iridium is heated to 89.7°C, and then dropped into 20.0 g of water in a foam-cup calorimeter. The temperature of the water went from 20.1°C to 22.6°C. Calculate the specific heat of iridium (specific heat of water = 4.18 J/g.°C)
Answer: The specific heat of iridium is 0.130 J/g°C
Explanation:
When iridium is dipped in water, the amount of heat released by iridium will be equal to the amount of heat absorbed by water.
[tex]Heat_{\text{absorbed}}=Heat_{\text{released}}[/tex]
The equation used to calculate heat released or absorbed follows:
[tex]Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})[/tex]
[tex]m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)][/tex] ......(1)
where,
q = heat absorbed or released
[tex]m_1[/tex] = mass of iridium = 23.9 g
[tex]m_2[/tex] = mass of water = 20.0 g
[tex]T_{final}[/tex] = final temperature = 22.6°C
[tex]T_1[/tex] = initial temperature of iridium = 89.7°C
[tex]T_2[/tex] = initial temperature of water = 20.1°C
[tex]c_1[/tex] = specific heat of iridium = ?
[tex]c_2[/tex] = specific heat of water = 4.18 J/g°C
Putting values in equation 1, we get:
[tex]23.9\times c_1\times (22.6-89.7)=-[20\times 4.18\times (22.6-20.1)][/tex]
[tex]c_1=0.130J/g^oC[/tex]
Hence, the specific heat of iridium is 0.130 J/g°C
Taking into account the definition of calorimetry, the specific heat of iridium is 0.13 [tex]\frac{J}{gC}[/tex].
CalorimetryCalorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).
So, the equation that allows to calculate heat exchanges is:
Q = c× m× ΔT
where:
Q is the heat exchanged by a body of mass m.c specific heat substance.ΔT is the temperature variation.Specific heat of iridiumIn this case, you know:
For iridium:Mass of iridium = 13.5 gInitial temperature of gold= 89.3 °CFinal temperature of gold= 22.6 ºCSpecific heat of gold = UnknownFor water:Mass of water = 20 gInitial temperature of water= 20.1 ºCFinal temperature of water= 22.6 ºCSpecific heat of water = 4.18 [tex]\frac{J}{gC}[/tex]Replacing in the expression to calculate heat exchanges:
For iridium: Qiridium= c × 23.9 g× (22.6 C - 89.7 C)
For water: Qwater= 4.186 [tex]\frac{J}{gC}[/tex]× 20 g× (22.6 C - 20.1 C)
If two isolated bodies or systems exchange energy in the form of heat, the quantity received by one of them is equal to the quantity transferred by the other body. That is, the total energy exchanged remains constant, it is conserved.
Then, the heat that the gold gives up will be equal to the heat that the water receives. Therefore:
- Qiridium = + Qwater
- c × 23.9 g× (22.6 C - 89.7 C)= 4.18 [tex]\frac{J}{gC}[/tex]× 20 g× (22.6 C - 20.1 C)
Solving:
c × 23.9 g× ( 89.7 C - 22.6 C)= 4.18 [tex]\frac{J}{gC}[/tex]× 20 g× (22.6 C - 20.1 C)
c × 23.9 g× 67.1 C= 4.18 [tex]\frac{J}{gC}[/tex]× 20 g× 2.5 C
c × 1603.69 g×C= 209 J
[tex]c=\frac{209 J}{1603.69 gC}[/tex]
c= 0.13 [tex]\frac{J}{gC}[/tex]
Finally, the specific heat of iridium is 0.13 [tex]\frac{J}{gC}[/tex].
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A sample of 0.495 grams of solid KHP is weighed into an Erlenmeyer flask. This sample is titrated with a sodium hydroxide solution, and 28.56 mL of NaOH are required to reach the endpoint. The sodium hydroxide solution is then used to titrate a sample of phosphoric acid of unknown concentration. It requires 29.88 mL of NaOH to react with 10.33 mL of H3PO4 solution. What is the concentration of the phosphoric acid?
Answer:
The concentration of the H₃PO₄ solution is 0,245M
Explanation:
The first titration is:
KHP + NaOH → KP⁻ + Na⁺ + H₂O
0,495g of KHP are:
0,495g×[tex]\frac{1mol}{204,22g}[/tex]= 2,42x10⁻³ moles of KHP
As 1 mole of KHP reacts with 1 mole of NaOH, moles of NaOH are 2,42x10⁻³ moles.
As volume required was 28,56mL, the concentration of the NaOH solution is:
2,42x10⁻³ moles / 0,02856L = 0,0849M
The titration of the phosporic acid with NaOH occurs as follows:
H₃PO₄ + NaOH → H₂PO₄⁻ + Na⁺ + H₂O
If were required 29,88mL of NaOH, the moles of NaOH spent were:
0,0849M×0,02988L = 2,54x10⁻³ moles of NaOH that are the same than H₃PO₄ moles.
As the volume of the solution of H₃PO₄ was 10,33mL, the concentration of the H₃PO₄ solution is:
2,54x10⁻³ moles of H₃PO₄ / 0,01033L = 0,245M
I hope it helps!
Final answer:
The concentration of the phosphoric acid is calculated using the molarity of a standardized NaOH solution obtained from a titration with KHP. The determined NaOH molarity is then applied to find the moles of phosphoric acid reacted in its own titration, which leads to the final concentration of the acid.
Explanation:
To determine the concentration of the phosphoric acid (H3PO4), we first need to calculate the molarity of the sodium hydroxide (NaOH) solution using the titration with potassium hydrogen phthalate (KHP). Since 0.495 grams of KHP was titrated with 28.56 mL of NaOH, we can calculate the moles of KHP used:
Molar mass of KHP (KH2C8H4O4) ≈ 204.22 g/molMoles of KHP = 0.495 g / 204.22 g/mol = 0.00242 molThe reaction between KHP and NaOH is 1:1, so moles of NaOH = moles of KHP = 0.00242 molMolarity of NaOH = moles/volume (in liters) = 0.00242 mol / 0.02856 L = 0.0847 MNow, using the concentration of NaOH, we can find the concentration of phosphoric acid. Given that 29.88 mL of the NaOH solution is required to titrate the 10.33 mL of H3PO4, we have:
Moles of NaOH = 0.0847 M * 0.02988 L = 0.00253 molThe ratio of NaOH to H3PO4 in the balanced equation is 3:1, so moles of H3PO4 = 0.00253 mol / 3 = 0.000843 molConcentration of H3PO4 = moles/volume (in liters) = 0.000843 mol / 0.01033 L = 0.0816 MThe reaction described by this equation
O3(g)+NO(g)--> O2(g)+NO2(g)
has the following rate law at 310K.
rate of reaction=k[O3][NO] k=3.0*10^6M^-1*s^-1
Given that [O3]=5.0x10^-4M and NO=6.0x10^-5M at t=0 calculate the rate of the reaction at t=0
What is the overall order of this reaction?
Answer :
The rate of the reaction at t=0 is, [tex]9.0\times 10^{-13}M.s^{-1}[/tex]
The overall order of reaction is, second order reaction.
Explanation :
Rate law : It is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.
The general reaction is:
[tex]A+B\rightarrow C+D[/tex]
The general rate law expression for the reaction is:
[tex]\text{Rate}=k[A]^a[B]^b[/tex]
where,
a = order with respect to A
b = order with respect to B
R = rate law
k = rate constant
[tex][A][/tex] and [tex][B][/tex] = concentration of A and B reactant
Now we have to determine the rate law for the given reaction.
The given balanced equations is:
[tex]O_3(g)+NO(g)\rightarrow O_2(g)+NO_2(g)[/tex]
In this reaction, [tex]O_3[/tex] and [tex]NO[/tex] are the reactants.
The rate law expression for the reaction is:
[tex]\text{Rate}=k[O_2][NO][/tex] ..........(1)
Given :
Rate constant = [tex]k=3.0\times 10^{-5}M^{-1}s^{-1}[/tex]
Concentration of [tex]O_3[/tex] = [tex]5.0\times 10^{-4}M[/tex]
Concentration of [tex]NO[/tex] = [tex]6.0\times 10^{-5}M[/tex]
Now put all the given values in equation 1, we get:
[tex]\text{Rate}=(3.0\times 10^{-5}M^{-1}s^{-1})\times (5.0\times 10^{-4}M)\times (6.0\times 10^{-5}M)[/tex]
[tex]\text{Rate}=9.0\times 10^{-13}M.s^{-1}[/tex]
Thus, the rate of the reaction at t=0 is, [tex]9.0\times 10^{-13}M.s^{-1}[/tex]
Now we have to determine the overall order of reaction.
From the given rate law expression we conclude that,
The order of reaction with respect to [tex]O_3[/tex] is, first order reaction.
The order of reaction with respect to [tex]NO[/tex] is, first order reaction.
Thus, overall order of reaction will be:
Overall order of reaction = 1 + 1 = 2
Thus, the overall order of reaction is second order reaction.
The calculated rate of the reaction at t=0 is 9.0×10−1 M×s−1, and the overall order of the reaction is second order, resulting from being first order with respect to each reactant.
Explanation:The rate of the reaction O3(g) + NO(g) → O2(g) + NO2(g) at t=0 can be calculated using the given rate law and concentrations. The rate law is rate = k[O3][NO], where k is the rate constant, and the brackets denote the concentration of the reactants O3 and NO respectively. To calculate the reaction rate at t=0, we plug in the given values: rate = (3.0×106 M−1×s−1)(5.0×10−4 M)(6.0×10−5 M), which gives a rate of 9.0×10−1 M×s−1.
The overall order of the reaction can be determined by looking at the exponents of the reactant concentrations in the rate law. Since the rate law is rate = k[O3]1[NO]1, it is first order with respect to both O3 and NO. This means that the overall order of the reaction is the sum of the individual orders, which is 1 + 1 = 2, making the reaction second order overall.
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What is the concentration in molarity of a solution made using 50.0 grams of C6H12O6 in 300.0 mL of water?
Please help ASAP!!! :(
Answer: concentration in Molarity it's actually Molarity
Molarity=concentration/molar mass
Concentration=50g/0.3dm³=166.67g/dm³
Molar mass=180g/mol
Molarity=0.926mol/dm³
Answer:
Answer is =0. 925 mol L−1
Explanation:
C₆H₁₂O₆ is formula of Glucose
For Molarity, we must know the following things
• the number of moles of solute present in solution
• the total volume of the solution
we know the mass of one mole of Glucose = 180.156 g/mol
Number of moles = Given Mass of substance / Mass of one mole
No of moles = 50g / 180.156 g/mol
= 0.277 moles
Now we know that molarity is expressed per liter of solution. Since you dissolve 0.277 moles of potassium chloride in 300. mL of solution, you can say that 1.0 L will contain
For 300 ml of solution, no of moles are = 0.277 moles
For 1 ml of solution, no of moles are = 0.277/300 moles
For 1(1000) ml of solution, no of moles are= 0. 277/300 x 1000
= 0.925 moles/ L
Answer is =0. 925 mol L−1
An experimental spacecraft consumes a special fuel at a rate of 353 L/min . The density of the fuel is 0.700 g/mL and the standard enthalpy of combustion of the fuel is − 57.9 kJ/g . Calculate the maximum power (in units of kilowatts) that can be produced by this spacecraft. 1 kW = 1 kJ/s
Explanation:
The given data is as follows.
Space craft fuel rate = 353 L/min
As 1 liter equals 1000 ml and 1 min equals 60 seconds.
So, [tex]353 \times \frac{1000 ml}{60 sec}[/tex]
= 5883.33 ml/sec
It is also given that density of the fuel is 0.7 g/ml and standard enthalpy of combustion of fuel is -57.9 kJ/g.
Fuel rate per second is 5883.33 ml.
[tex]5883.33 ml \times 0.7 g/ml[/tex]
= 4118.33 g
Hence, calculate the maximum power as follows.
Power = Fuel consumption rate × (-enthalpy of combustion)
= 4118.33 g/s \times 57.9 kJ/g
= 238451.36 kJ/s
or, = 238451.36 kW
Thus, we can conclude that maximum power produced by given spacecraft is 238451.36 kW.
A buret is filled with 0.1517 M naoh A 25.0 mL portion of an unknown acid and two drops of indicator are added to an Erlenmeyer flask, and the titration experiment is carried out. If the initial buret reading was 0.55 mL, and the buret reading at the end point was 22.50 mL, what is the molarity of the unknown acid?
Answer:
molarity of acid =0.0132 M
Explanation:
We are considering that the unknown acid is monoprotic. Let the acid is HA.
The reaction between NaOH and acid will be:
[tex]NaOH+HA--->NaA+H_{2}O[/tex]
Thus one mole of acid will react with one mole of base.
The moles of base reacted = molarity of NaOH X volume of NaOH
The volume of NaOH used = Final burette reading - Initial reading
Volume of NaOH used = 22.50-0.55= 21.95 mL
Moles of NaOH = 0.1517X21.95=3.33 mmole
The moles of acid reacted = 3.33 mmole
The molarity of acid will be = [tex]\frac{mmole}{volumne(mL)}=\frac{0.33}{25}=0.0132M[/tex]
The problem is about acid-base titration used in Chemistry. A 1:1 reaction between NaOH and the unknown acid is assumed. The molarity of the unknown acid is calculated as 0.1332 M.
Explanation:This problem pertains to acid-base titration, a common method in Chemistry for determining the concentration of an unknown acid or base. The initial and final buret readings indicate the volume of NaOH used in the reaction: 22.50 mL - 0.55 mL = 21.95 mL, which is 0.02195 L. Using the molarity of NaOH (0.1517 M), we can find the moles of NaOH used: 0.1517 M * 0.02195 L = 0.00333 mol. Since the reaction between NaOH and the unknown acid is assumed to be 1:1, the moles of the unknown acid should also be 0.00333. Therefore, to obtain the molarity of the unknown acid, divide the moles of the acid by the volume of the acid in liters (25.0 mL = 0.025 L): 0.00333 mol / 0.025 L = 0.1332 M. Therefore, the molarity of the unknown acid is 0.1332 M.
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Consider a galvanic cell based on the reaction Al^3+_(aq) + Mg_(s) rightarrow Al_(s) + Mg^2+ _(aq) The half-reactions are Al^3+ + 3 e^- rightarrow Al E degree = - 1.66 V Mg^2+ + 2 e^- rightarrow Mg E degree = - 2.37 V Give the balanced cell reaction and calculate E degree for the cell.
Answer: The standard cell potential of the cell is -0.71 V
Explanation:
The half reactions follows:
Oxidation half reaction: [tex]Mg\rightarrow Mg^{2+}+2e^-;E^o_{Mg^{2+}/Mg}=-2.37V[/tex] ( × 3)
Reduction half reaction: [tex]Al^{3+}(aq.)+3e^-\rightarrow Al(s);E^o_{Al^{3+}/Al}=-1.66V[/tex] ( × 2)
The balanced cell reaction follows:
[tex]2Al^{3+}(aq.)+3Mg(s)\rightarrow 2Al(s)+3Mg^{2+}(aq.)[/tex]
To calculate the [tex]E^o_{cell}[/tex] of the reaction, we use the equation:
[tex]E^o_{cell}=E^o_{cathode}-E^o_{anode}[/tex]
Substance getting oxidized always act as anode and the one getting reduced always act as cathode.
Putting values in above equation, we get:
[tex]E^o_{cell}=-2.37-(-1.66)=-0.71V[/tex]
Hence, the standard cell potential of the cell is -0.71 V
The thiocyanate polyatomic ion, SCN-, is commanly called a pseudohalogen because it acts very much like halide ions. For example, we know that pure halogens consists of diatiomic molecules, such as C12. Thiocanate ions form similar molecules in the following reaction2NaSCN +2H2SO4 + MnO2 -> (SCN)2 + 2H2O + MnSO4 + Na2SO4A) Write a conversion factor that could be used to convert between moles of NaSCN and moles of (SCN)2B) How many moles of (SCN)2 form when 0.05 moles of NaSCN react completely?C) What is the maximum number of moles of (SCN)2 that could form in the combination of 4 moles of NaSCN and 3 moles of MnSO4?D) Write a convertion factor that could be used to convert between moles of sulfuric acid, H2SO4 and moles manganese (II) sulfate, MnSO4.E) What is the minimum number of moles of H2SO4 that must react to form 1.7752 moles of manganese (II) sulfate?
Answer:
A) [tex]\frac{1mol(SCN)_{2}}{2molNaSCN}[/tex]
B) 0.025 mol (SCN)₂
C) 2 mol (SCN)₂
D) [tex]\frac{1molMnSO_{4}}{2molH_{2}SO_{4}}[/tex]
E) 3.5504 mol H₂SO₄
Explanation:
2NaSCN +2H₂SO₄ + MnO₂ → (SCN)₂ + 2H₂O + MnSO₄ + Na₂SO₄
A) A conversion factor could be [tex]\frac{1mol(SCN)_{2}}{2molNaSCN}[/tex] , as it has the units that we want to convert to in the numerator, and the units that we want to convert from in the denominator.
B) 0.05 mol NaSCN * [tex]\frac{1mol(SCN)_{2}}{2molNaSCN}[/tex] = 0.025 mol (SCN)₂
C) With 4 moles of NaSCN and 3 moles of MnSO₄, the reactant is NaSCN so we use that value to calculate the moles of product formed:
4 mol NaSCN * [tex]\frac{1mol(SCN)_{2}}{2molNaSCN}[/tex] = 2 mol (SCN)₂
D) [tex]\frac{1molMnSO_{4}}{2molH_{2}SO_{4}}[/tex]
E) 1.7752 mol MnSO₄ * [tex]\frac{2molH_{2}SO_{4}}{1molMnSO_{4}}[/tex] = 3.5504 mol H₂SO₄
A 5.00 mL of a salt solution of unknown concentration was mixed with 35.0 mL of 0.523 M AgNO3. The mass of AgCl solid formed was 0.508 g. _ AgNO3(aq) + _ NaCl(aq) → _ AgCl(s) + _ NaNO3(aq) What is the chemical term for the silver chloride solid that is formed?
Answer:
The chemical term in the equation for the precipitate of AgCl(s) is n=3.54*10^-3
Explanation:
the quantity of AgCl(s) in moles is:
n = 0.508g / 143.32 g/mol = 3.54*10^-3 mol
to verify it the mass of AgNO3 involved in the reaction should be
n AgNO3 required = n = 3.54*10^-3 mol
the mass of n involved should be higher than n AgNO3
n existing = V*N = 0.523 mol/L * 35*10^-3 L = 18.305*10^-3 mol
The chemical term of the reaction
AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)
Is when appears red brick in the solution indicating the formation of the precipitate
In the tetrachloromethane (carbon tetrachloride) molecule the Cl-C-Cl bond angle is 109.5º. Which distribution of electrons around the central atom provides the best explanation for this bond angle?
3 shared pairs, 1 lone pair
4 shared pairs
2 shared pairs, 2 lone pairs
1 shared pair, 3 lone pairs
Answer:
4 shared pairs
Explanation:
According to the VESPR, a molecule with a central atom C linked to 4 Cl would form a tetrahedral, whose angles are 109.5°. When more lone pairs are added, the repulsion is greater due to the unshared electrons leading to a distorted tetrahedral. The more lone pairs, the lower the bond angle.
What is the concentration of ammonia in a solution if 23.4 mL of a 0.117 M solution of HCl are needed to titrate a 100.0 mL sample of the solution?
Answer: 0.0274 M
Explanation:-
The balanced chemical solution is:
[tex]NH_4OH(aq)+HCl(aq)\rightarrow NH_4Cl(aq)+H_2O(l)[/tex]
According to the neutralization law,
[tex]n_1M_1V_1=n_2M_2V_2[/tex]
where,
[tex]M_1[/tex] = molarity of [tex]HCl[/tex] solution = 0.117 M
[tex]V_1[/tex] = volume of [tex]HCl[/tex] solution = 23.4 ml
[tex]M_2[/tex] = molarity of [tex]NH_4OH[/tex] solution = ?
[tex]V_2[/tex] = volume of [tex]NH_4OH[/tex] solution = 100.0 ml
[tex]n_1[/tex] = valency of [tex]HCl[/tex] = 1
[tex]n_2[/tex] = valency of [tex]NH_4OH[/tex] = 1
[tex]1\times 0.117M\times 23.4=1\times M_2\times 100.0[/tex]
[tex]M_2=0.0274[/tex]
Therefore, the concentration of ammonia in a solution will be 0.0274 M
A 6.22-kg piece of copper metal is heated from 20.5 °C to 324.3 °C. The specific heat of Cu is 0.385 Jg-1°C-1.a.Calculate the heat absorbed (in kJ) by the metal.b.How close is this heat capacity to the expected heat capacity at the classical limit?
Answer:
a) 727.5 kJ
Explanation:
Step 1: Data given
Mass of the piece of copper = 6.22 kg
Initial temperature of the copper = 20.5 °C
Final temperature of the copper = 324.3 °C
Specific heat of copper = 0.385 J/g°C
Step 2:
Q = m*c*ΔT
⇒ with Q = heat transfer (in J)
⇒ with m = the mass of the object (in grams) = 6220 grams
⇒ with c = the specific heat capacity = 0.385 J/g°C
⇒ with ΔT = T2 -T1 = 324.3 - 20.5 = 303.8
Q = 6220 grams * 0.385 J/g°C * 303.8 °C
Q = 727509.9 J = 727.5 kJ
b) This heat capacity is the heat capacity given for a copper at a temperature of 25°C
The heat absorbed by the copper metal is 727.5 kJ.
Explanation:To calculate the heat absorbed by the copper metal, we can use the formula Q = mcΔT, where Q is the heat absorbed, m is the mass of the copper, c is the specific heat of copper, and ΔT is the change in temperature. Plugging in the given values, we get Q = 6.22 kg * 0.385 J/g°C * (324.3°C - 20.5°C).
Simplifying the equation, we get Q = 6.22 kg * 0.385 J/g°C * 303.8°C. Converting grams to kilograms, and simplifying further, we get Q = 727.5 kJ.
The expected heat capacity at the classical limit is not provided in the information given, so we cannot determine how close the calculated heat capacity is to the expected value.
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A 25.0 g piece of aluminum (which has a molar heat capacity of 24.03 J/mol°C) is heated to 86.4°C and dropped into a calorimeter containing water (the specific heat capacity of water is 4.18 J/g°C) initially at 21.1°C. The final temperature of water is 26.8°C. Calculate the mass of water in the calorimeter.
a. 1.7 g
b. 0.51 g
c. 150 g
d. 56 g
e. 61 g
Answer:
m H2O = 56 g
Explanation:
Q = mCΔT∴ The heat ceded (-) by the Aluminum part is equal to the heat received (+) by the water:
⇒ - (mCΔT)Al = (mCΔT)H2O
∴ m Al = 25.0 g
∴ Mw Al = 26.981 g/mol
⇒ n Al = (25.0g)×(mol/26.981gAl) = 0.927 mol Al
⇒ Q Al = - (0.927 mol)(24.03 J/mol°C)(26.8 - 86.4)°C
⇒ Q Al = 1327.64 J
∴ mH2O = Q Al / ( C×ΔT) = 1327.64 J / (4.18 J/g.°C)(26.8 - 21.1)°C
⇒ mH2O = 55.722 g ≅ 56 g
To calculate the mass of water in the calorimeter, use the conservation of energy principle and the specific heat capacity formula. The mass of water in the calorimeter is 61 g.
Explanation:To calculate the mass of water in the calorimeter, you can use the conservation of energy principle. The heat lost by the aluminum equals the heat gained by the water. The heat gained by water can be calculated using the specific heat capacity formula: Q = mcΔT.
From the given information, we know the initial temperature of the water (21.1°C), the final temperature of the water (26.8°C), and its specific heat capacity (4.18 J/g°C). Considering the amount of heat lost by the aluminum and the heat gained by the water, you can calculate the mass of water in grams to be 61 g.
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