Answer:
C) H⁺
Explanation:
When we are balancing the reaction in an acid medium, hydrogen is balanced using the H⁺ species. This is most likely the intended answer of your question.
When the reaction takes place not in an acid medium, but in an alkaline one, then hydrogen is present as the OH⁻ species. However this option is not given in your question.
Thus the answer is option C).
Consider the following reaction to generate hydrogen gas: Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g) The hydrogen gas is collected by displacement of water at 35.0 °C at a total pressure of 745 torr. The vapor pressure of water at 35.0 °C is 42 torr. Calculate the partial pressure of H2 (in atm) if 353.2 mL of gas is collected over water from this method.
Answer:
0.925 atm
Explanation:
By Dalton's Law, the total pressure of a gas mixture is the sum of the partial pressure of its components. The vapor pressure of the water is the pressure that some molecules that evaporated do under the liquid surface. The gas and the liquid are at equilibrium. So, the gas mixture is water vapor and hydrogen gas.
Ptotal = Pwater + PH₂
745 = 42 + PH₂
PH₂ = 703 torr
Transforming to atm:
1 atm ------------------760 torr
x ------------------ 703 torr
By a simple direct three rule
760x = 703
x = 0.925 atm
mastering chemistry hat do you predict for the height of a barometer column based on 1-iodododecane, when the atmospheric pressure is 751 torr ? Note that 1 torr corresponds to 1 mm of a liquid mercury column.
Answer:
the height of a iodododecane barometer column =66.46mm
Explanation:
we will the density of liquid 1-iodododecane and the density of mecury (compare with the given value of mercury)
when the atmospheric pressure is 751 torr ?
the compound 1-iodododecane has a density of 1.2g/mL
the density of mercury is 13.56g/mL
for mercury at
1 torr corresponds to 1 mm of a liquid mercury column= 13.56g/ml
for 1-iodododecane
751toor = ? at 1.2g/mL
1 torr = 1mm = 13.56
751 torr of mercury = 751mm = 13.56
751 toor of iodo = ? = 1.2
751mm = 13.56
? ====1.2
1.2 * 751)/13.56 =66.46mm
the height of a iodododecane barometer column =66.46mm
The height of a barometer column with 1-iodododecane at 751 torr would depend on the density of 1-iodododecane relative to mercury. Using the hydrostatic pressure formula, the height can be determined with the known density of 1-iodododecane.
Explanation:When considering the height of a barometer column based on 1-iodododecane at an atmospheric pressure of 751 torr, it's important to account for the density of 1-iodododecane relative to that of mercury. Since the density of the 1-iodododecane will be different from mercury (13.6 g/cm³), the height of the barometer column for the same atmospheric pressure would also be different. To find the height, one would need to use the formula for hydrostatic pressure, p = ρgh, where ρ is the density of the fluid, g is the acceleration due to gravity, and h is the height of the column. With the density of 1-iodododecane known, one could rearrange the formula to solve for h to find the expected height of the barometer column at 751 torr.
Sulfur dioxide has a vapor pressure of 462.7 mm Hg at –21.0 °C and a vapor pressure of 140.5 mm Hg at –44.0 °C. What is the enthalpy of vaporization of sulfur dioxide? (R = 8.314 J/K⋅mol)
Final Answer:
The enthalpy of vaporization [tex](\( \Delta H_{\text{vap}} \))[/tex]of sulfur dioxide is approximately[tex]\( 28.5 \, \text{kJ/mol} \)[/tex].
Explanation:
To find the enthalpy of vaporization [tex](\( \Delta H_{\text{vap}} \))[/tex], we use the Clausius-Clapeyron equation:
[tex]\[ \ln\left(\frac{P_2}{P_1}\right) = -\frac{\Delta H_{\text{vap}}}{R}\left(\frac{1}{T_2} - \frac{1}{T_1}\right) \][/tex]
Given vapor pressures:
[tex]\( P_1 = 462.7 \, \text{mm Hg} \) at \( T_1 = -21.0 \, \text{°C} \),[/tex]
[tex]\( P_2 = 140.5 \, \text{mm Hg} \) at \( T_2 = -44.0 \, \text{°C} \).[/tex]
Convert temperatures to Kelvin:
[tex]\[ T_1 = -21.0 \, \text{°C} + 273.15 = 252.15 \, \text{K} \][/tex]
[tex]\[ T_2 = -44.0 \, \text{°C} + 273.15 = 229.15 \, \text{K} \][/tex]
Now, substitute values into the equation:
[tex]\[ \ln\left(\frac{140.5}{462.7}\right) = -\frac{\Delta H_{\text{vap}}}{8.314}\left(\frac{1}{229.15} - \frac{1}{252.15}\right) \][/tex]
Solving for [tex]\( \Delta H_{\text{vap}} \):[/tex]
[tex]\[ \Delta H_{\text{vap}} = -8.314 \times \ln\left(\frac{140.5}{462.7}\right) \times \frac{1}{229.15 - 252.15} \][/tex]
After calculation, [tex]\( \Delta H_{\text{vap}} \)[/tex]is approximately[tex]\( 28.5 \, \text{kJ/mol} \).[/tex]
In conclusion, the enthalpy of vaporization for sulfur dioxide is determined through the Clausius-Clapeyron equation, with precise calculations yielding an enthalpy value of [tex]\( 28.5 \, \text{kJ/mol} \)[/tex].
Calculate the ph of a buffer that is 0.145 m hc2h3o2 and 0.202 m kc2h3o2. The ka for hc2h3o2 is 1.8 × 10-5.
Answer:
pH = 4.8
Explanation:
A buffer is formed by a weak acid (0.145 M HC₂H₃O₂) and its conjugate base (0.202 M C₂H₃O₂⁻ coming from 0.202 M KC₂H₃O₂). The pH of a buffer system can be calculated using Henderson-Hasselbalch's equation.
[tex]pH = pKa + log\frac{[base]}{[acid]} \\pH = -log(1.8 \times 10^{-5} )+log(\frac{0.202M}{0.145M} )\\pH=4.8[/tex]
In the diagram, the black line represents the concentration of a reactant and the green line represents the concentration of a product.
Which statement best describes the reaction rate?
A. The product maintains an constant concentration in the first half of the reaction.
B. At the end of the reaction, both product and reactants are of a constant concentration.
C. The reactants maintain an constant concentration in the first half of the reaction.
D. At the end of the reaction, both product and reactants are of an equal concentration.
I think is A. Please correct me if I am wrong. Thank you!
Answer:
B. At the end of the reaction, both product and reactants are of a constant concentration.
Explanation:
Option A and C are similar as they both refer to constant concentration of product and reactant respectively in first half. As in the graph, the concentration of reactant and product changes (concentration of reactant decreases and concentration of product increase) with time in the first half[tex]^{*}[/tex] of the reaction. This made both A and C option wrong.Option D is also wrong as at the end of reaction[tex]^{**}[/tex] the line of concentration of product and reactant do not coincide which means they are not equal.Option B is correct as we take the end of reaction at the point where the concentration of reactant and product won't change much or become constant[tex]^{*}[/tex]first half time is the when concentration of reactant reduces to 50% of initial concentration which you can nearly assume on or before the point of intersection of both the concentration graphs.
[tex]^{**}[/tex]end of reaction is the time when the reaction completes which is theoretically infinite but generally we take end of the reaction as the time when the slope of concentration curve becomes nearly zero or the time when change in concentration of reactant and product is negligible.
Answer:
B. At the end of the reaction, both product and reactants are of a constant concentration.
Explanation:
Got it right on the test!
Magnesium hydroxide, the active ingredient in milk of magnesia, neutralizes stomach acid, primarily HCl, according to the reaction Mg(OH)2(aq) + 2HCl(aq) → 2H2O(l) + MgCl2(aq) How much HCl in grams can be neutralized by 5.50 g of Mg(OH)2?
Answer:
6.935g
Explanation:
From the question above, we can see that 1 mole of magnesium hydroxide neutralized 2 moles of hydrochloric acid.
Now, let's calculate the actual number of moles of magnesium hydroxide reacted. We can do this by dividing the mass of the magnesium hydroxide by the molar mass. Molar mass of the magnesium hydroxide is 24 + 2(17) = 58g/mol
The number of moles thus produced is 5.5/58 = 0.095moles
From the first relation we established that 1 mole of magnesium hydroxide reacted with 2 moles of hydrochloric acid. Hence, 0.095moles of magnesium hydroxide will yield 2 × 0.095 moles of hydrochloric acid = 0.190 moles
We then calculate the mass of HCl that be neutralized by multiplying the number of moles by the molar mass. The molar mass of HCl is 1 + 35.5 = 36.5g/mol.
The mass of HCl neutralized = 36.5 × 0.190 = 6.935g
Answer: The mass of [tex]HCl[/tex] neutralized can be, 6.88 grams.
Explanation : Given,
Mass of [tex]Mg(OH)_2[/tex] = 5.50 g
Molar mass of [tex]Mg(OH)_2[/tex] = 58.3 g/mol
Molar mass of [tex]HCl[/tex] = 36.5 g/mol
First we have to calculate the moles of [tex]Mg(OH)_2[/tex]
[tex]\text{Moles of }Mg(OH)_2=\frac{\text{Given mass }Mg(OH)_2}{\text{Molar mass }Mg(OH)_2}[/tex]
[tex]\text{Moles of }Mg(OH)_2=\frac{5.50g}{58.3g/mol}=0.0943mol[/tex]
Now we have to calculate the moles of [tex]HCl[/tex]
The balanced chemical equation is:
[tex]Mg(OH)_2(aq)+2HCl(aq)\rightarrow 2H_2O(l)+MgCl_2(aq)[/tex]
From the balanced reaction we conclude that
As, 1 mole of [tex]Mg(OH)_2[/tex] react with 2 mole of [tex]HCl[/tex]
So, 0.0943 moles of [tex]Mg(OH)_2[/tex] react with [tex]0.0943\times 2=0.1886[/tex] moles of [tex]HCl[/tex]
Now we have to calculate the mass of [tex]HCl[/tex]
[tex]\text{ Mass of }HCl=\text{ Moles of }HCl\times \text{ Molar mass of }HCl[/tex]
[tex]\text{ Mass of }HCl=(0.1886moles)\times (36.5g/mole)=6.88g[/tex]
Therefore, the mass of [tex]HCl[/tex] neutralized can be, 6.88 grams.
Which pair of molecules has the strongest dipole-dipole interactions?
CH4 and CH4 NH3 and CH4 CO2 and CH4 NH3 and NH3 CO2 and CO2
Answer: NH3 and NH3
Explanation:
If hydrogen is bonded to a highly electronegative element, a strong dipole-dipole attraction is set up with strength ten times greater than normal dipole-dipole attractions, and it is crystal clear that electronegativity increase from left to right across the period and it decreases down the group. Nitrogen being electronegative more than Oxygen will exhibit a greater dipole-dipole attraction. As such, NH3 and NH3 is the right answer.
The pair of molecules with the strongest dipole-dipole interactions among the given options is NH3 and NH3 due to the molecule's polar nature and resultant net dipole.
Explanation:Among the options listed, the pair of molecules with the strongest dipole-dipole interactions is NH3 and NH3. Dipole-dipole interactions are attractive forces between the positive end of one polar molecule and the negative end of another polar molecule. They occur when the molecule is polar, meaning there is an unequal distribution of electrons and hence a net dipole. NH3, or ammonia, is a polar molecule because it has a pyramidal shape with a net dipole. This results in strong dipole-dipole interactions between NH3 molecules, stronger than CH4 (methane) with CH4, CO2 (carbon dioxide) with CO2, or NH3 with CH4 as these molecules are nonpolar and thus exhibit weaker London dispersion forces and not dipole-dipole interactions.
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In a solution, the solvent In a solution, the solvent can be a liquid or gas. A. is the substance present in the smallest concentration. B. can be a solid, liquid, or gas. C. is a liquid. D. is never a solid.
Answer:
Can either be a solid, a liquid or a gas
Explanation:
A solvent can either be a solid, liquid or a gas. It is the carrier medium in a solution. It is the one in which the solute is dissolved.
Although quite unusual, a solvent might also be a solid. An important application of this can be seen in the production of alloys. Alloys are mixture of metals. To produce let’s say an alloy containing just two metals, the use of a solid solvent is needed. Here, one of the two metals is known as the base metal. It is this base metal that will serve as the carrier medium for the other metal
What volume of carbon dioxide is produced when 0.489 mol of calcium carbonate reacts completely according to the following reaction at 0°C and 1 atm? calcium carbonate ( s ) calcium oxide ( s ) + carbon dioxide ( g )
Answer:
11.0L of carbon dioxide is produced
Explanation:
Balanced equation: [tex]CaCO_{3}(s)\rightarrow CaO(s)+CO_{2}(g)[/tex]
According to balanced equation, 1 mol of [tex]CaCO_{3}[/tex] produces 1 mol of [tex]CO_{2}[/tex]
So, 0.489 mol of [tex]CaCO_{3}[/tex] produces 0.489 mol of [tex]CO_{2}[/tex]
Let's assume [tex]CO_{2}[/tex] behaves ideally.
So, [tex]P_{CO_{2}}V_{CO_{2}}=n_{CO_{2}}RT[/tex]
where P is pressure, V is volume , n is number of moles, R is gas constant and T is temperature in kelvin
Plug-in all the values in the above equation-
[tex](1atm)\times V_{CO_{2}}=(0.489mol)\times (0.0821L.atm.mol^{-1}.K^{-1})\times (273K)[/tex]
or, [tex]V_{CO_{2}}=11.0L[/tex]
So, 11.0L of carbon dioxide is produced
What is the difference between stating "The electron is located at a particular point in space" and "There is a high probability that the electron is located at a particular point in space"? Choose all that apply. A. In the first statement we know where electron is. B. In the second statement, we are saying that we have no information about the position of the electron. C. In the second statement, we are saying that we know the probability of the electron being at a point, but we dont know exactly where it is. D. In the first statement, we cannot define the exact location of the electron.
The difference between stating "The electron is located at a particular point in space" and "There is a high probability that the electron is located at a particular point in space" is in the first statement, we cannot define the exact location of the electron.
What is an electron ?The elementary electric charge of the electron is a negative one, making it a subatomic particle. Due to their lack of known components or substructure, electrons, which are members of the first generation of the lepton particle family, are typically regarded to be elementary particles.
Quarks make up protons and neutrons, but not electrons. As far as we can know, quarks and electrons are basic particles that are not composed of lesser particles.
Thus, option D is correct.
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The halogens form a series of compounds with each other, which are called interhalogens. Examples are bromine chloride (BrCl), iodine bromide (IBr), bromine fluoride (BrF), and chlorine fluoride (ClF). Which is expected to have the lowest boiling point?
Final answer:
The interhalogen with the lowest boiling point is bromine chloride (BrCl) because both bromine and chlorine are smaller atoms compared to iodine.
Explanation:
The boiling point of a compound is determined by the strength of the intermolecular forces between its molecules. In the case of the interhalogens, the boiling point generally increases as the size and atomic mass of the halogen atoms increase. Therefore, the interhalogen with the lowest boiling point would be the one with the smallest halogen atom.
Among the given examples, bromine chloride (BrCl) has the lowest boiling point because both bromine and chlorine are smaller atoms compared to iodine. Iodine bromide (IBr) would have a higher boiling point since iodine is larger than both bromine and chlorine.
Similarly, bromine fluoride (BrF) would have a higher boiling point compared to bromine chloride due to the presence of a larger fluorine atom. Lastly, chlorine fluoride (ClF) would have the highest boiling point because both chlorine and fluorine are smaller atoms compared to bromine.
What is the equation for the energy levels of the hydrogen atom
Answer: E = (13.6 eV) [1/nf² - 1/ni²]
En = (-13.6 eV)/n²
where n=1,2,3...
Explanation:
According to Bohr's theory each spcified energy value( E1,E2,E3...) is called energy level of the atom and the only allowable values are given by the equation
En = (-13.6 eV)/n²
The energy change (ΔE) that accompaies the leap of an electron from one energy level to another is given by equation
E = (13.6 eV) [1/nf² - 1/ni²]
The equation for the energy levels of the hydrogen atom is given by the Bohr formula: En = -13.6 eV / n^2. The energy levels are inversely proportional to the square of the principal quantum number.
Explanation:The question concerns the equation for the energy levels of the hydrogen atom. According to Bohr's model, the energy levels of a hydrogen atom, which consists of a single electron orbiting a single proton, are given by the formula:
En = -13.6 eV / n2
Here, En represents the energy of an electron at a particular level n, which is known as the principal quantum number. This number can be any positive integer (n = 1, 2, 3, ...), and the energy level becomes less negative as n increases. The ground state energy of the hydrogen atom, when n = 1, is
-2.18 x 10-18 joules
Transitions between these energy levels result in the emission or absorption of light at specific wavelengths, giving rise to the hydrogen spectral series. Notably, the Lyman series corresponds to transitions ending at n=1, and the Balmer series ends at n=2.
‘A’ is an element which belongs to period 3, having 6 electrons in its valence shell. Below is a list of successive ionization energies (in kJ/mol) for period 3. IE2 = 2250 IE3 = 3360 IE4 = 4560 IE5 = 7010 IE6 = 8500 IE7 = 27,100 Identify the element ‘A’
Answer:
The element A is S (sulfur)
Explanation:
The elements for the 3erd period in the periodic table are Na, Mg, Al, Si, P, S, Cl and Ar.
The one that has 6 e⁻ in its valence shell is the S, because it is missing 2 e⁻ to reach the octet rule. 2 e⁻ to has the most stable noble gas conformation.
The IE of S = 3360 kJ/mol
It is a little lower than Cl because the electron is so far from the nucleus, that's why we have to apply a very low ionization energy to rip the electron off.
The element 'A' in question, which belongs to period 3 and has 6 valence electrons, is most likely aluminum (Al).
Explanation:Based on the given information, the element 'A' belongs to period 3 and has 6 valence electrons. To identify the element, we need to find the ionization energy values that match the given pattern. Looking at the successive ionization energies provided, we can see that the jump in ionization energy occurs after the third ionization. Since 'A' has 6 valence electrons, it is likely to be aluminum (Al), which fits the pattern.
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An example of a strong _____ agent important in biochemistry is _____. The redox potential for this molecule is _____. Please choose the correct answer from the following choices
a. oxidizing; O2;
b. negative reducing; NADH;
c. positive oxidizing; NADH;
d. positive reducing; O2;
e. negative reducing; NADH;
Answer:
Option B - reducing; NADH; negative
explanation:
Nicotinamide adenine dinucleotide, or NADH, is a compound, that's more actively used in the transportation of electron chain. It's evident that produced and make use NADH than FADH2 in the process that brings about energy creation.
NADH carries electrons from one reaction to another. Its Cofactor is in two forms in cells: NAD+ accepts electron from other molecule and hence reduced as an oxidizing agent while NADH is formed by this reaction, which can be used to donate electrons because it's a reducing agent. The main function of NAD is to transfer these reactions.
How many grams of silver chloride can be prepared by the reaction of 100.0 mL of 0.20 M silver nitrate with 100.0 mL of 0.15 M calcium chloride? Calculate the concentrations of each ion remaining in solution after precipitation is complete.
Answer:
Mass of AgCl = 2.87 g
[Ca²⁺] = 0.075 M
[Cl⁻] = 0.05 M
[NO₃⁻] = 0.10 M
Explanation:
The reaction between silver nitrate (AgNO₃) and calcium chloride (CaCl₂) is:
2AgNO₃(aq) + CaCl₂(aq) → 2AgCl(s) + Ca(NO₃)₂(aq)
The number of moles of the reactants are:
AgNO₃ = Volume (L)*concentration (M) = 0.1*0.2 = 0.02 mol
CaCl₂ = 0.1*0.15 = 0.015 mol
First, let's find which reactant is limiting. Testing for AgNO₃, the stoichiometry is:
2 moles of AgNO₃ ------------------------- 1 mol of CaCl₂
0.02 mol ------------------------- x
By a simple direct three rule:
2x = 0.02
x = 0.01 mol of CaCl₂, which is higher than was used, so CaCl₂ is in excess and AgNO₃ is the limiting reactant.
The stoichiometry between AgNO₃ and AgCl is:
2 moles of AgNO₃ ---------------- 2 moles of AgCl
0.02 mol ---------------- x
By a simple direct three rule
x = 0.02 mol of AgCl
The molar mass of AgCl is 143.32 g/mol, so the mass formed is:
m = 143.32*0.02 = 2.87 g
All the silver nitrate had reacted, and by the stoichiometry, only 0.01 mol of CaCl₂ reacted, so the number of moles remaining is:
nCaCl₂ = 0.015 - 0.01 = 0.005 mol
And the number of moles of Ca(NO₃)₂ formed is the same as CaCl₂ that reacted: 0.01 mol.
Both substances are in aqueous form, so, they produce ions:
CaCl₂ → Ca²⁺ + 2Cl⁻
By the stoichiometry: nCa²⁺ = 0.005 mol; nCl⁻ = 0.01 mol
Ca(NO₃)₂ → Ca²⁺ + 2NO₃⁻
By the stoichiometry: nCa²⁺ = 0.01 mol; nNO₃⁻ = 0.02 mol
The total volume is 0.2 L, so the ions concentrantions are:
[Ca²⁺] = (0.005 + 0.01)/0.2 = 0.075 M
[Cl⁻] = 0.01/0.2 = 0.05 M
[NO₃⁻] = 0.02/0.2 = 0.10 M
The concentrations of each ion remaining in solution after precipitation is complete is Mass of AgCl = 2.87 g, [Ca²⁺] = 0.075 M, [Cl⁻] = 0.05 m, [NO₃⁻] = 0.10 M.
What is silver chloride?Silver chloride is an ionic compound in which the silver is cation and the chloride is anion.
The reaction is
[tex]2AgNO_3(aq) + CaCl_2(aq) = 2AgCl(s) + Ca(NO_3)_2(aq)[/tex]
The number of moles of the reactants are:
[tex]AgNO_3 = Volume (L) \times concentration (M) \\\\= 0.1 \times 0.2 = 0.02 mol[/tex]
[tex]CaCl_2 = 0.1 \times 0.15 = 0.015 mol[/tex]
Now, finding the limiting reactant.
Testing for AgNO₃,
The stoichiometry is:
2 moles of AgNO₃ = 1 mol of CaCl₂
0.02 mol = x
By direct three rule:
2x = 0.02
[tex]AgNO_3[/tex] is the limiting reactant.
The stoichiometry between [tex]AgNO_3[/tex] and AgCl is:
2 moles of [tex]AgNO_3[/tex] = 2 moles of AgCl
0.02 mol = x
By a simple direct three rule
x = 0.02 mol of AgCl
The mass formed is
If the molar mass of AgCl is 143.32 g/mol
[tex]m = 143.32\times0.02 = 2.87 g[/tex]
Remaining number of moles are
nCaCl₂ = 0.015 - 0.01 = 0.005 mol
The substances will produce ions, because they are aqueous form.
[tex]CaCl_2 = Ca^2^++ 2Cl^-[/tex]
By the stoichiometry
nCa²⁺ = 0.005 mol
nCl⁻ = 0.01 mol
[tex]Ca(NO_3)_2 = Ca^2^+ + 2NO_3^-[/tex]⁻
By the rule of stoichiometry
nCa²⁺ = 0.01 mol
nNO₃⁻ = 0.02 mol
The volume is 0.2 L,
The concentration of ions are
[Ca²⁺] =[tex]\dfrac{(0.005 + 0.01)}{0.2} = 0.075 M[/tex]
[Cl⁻] = [tex]\dfrac{0.01}{0.2} = 0.05 M[/tex]
[NO₃⁻] = [tex]\dfrac{0.02}{0.2} = 0.10\; M[/tex]
Thus, the concentrations of each ion remaining in solution after precipitation is complete is Mass of AgCl = 2.87 g, [Ca²⁺] = 0.075 M, [Cl⁻] = 0.05 m, [NO₃⁻] = 0.10 M.
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A 275-mL flask contains pure helium at a pressure of 752 torr. A second flask with a volume of 475 mL contains pure argon at a pressure of 722 torr. If the two flasks are connected through a stopcock and the stopcock is opened, what is the partial pressure of each gas and the total pressure.?
Answer:
Total pressure = 732.9 torr
Partial pressure of helium =275.7 torr
Partial pressure of argon = 457.2 torr
Explanation:
Given data:
Volume of flask one = 275 mL
Pressure of helium = 752 torr
Volume of second flask = 475 mL
Pressure of argon = 722 torr
What is partial pressure = ?
What is total pressure = ?
Solution:
V₂ = 275 mL + 475 mL = 750 mL
For helium:
P₁V₁ = P₂V₂
P₂ = P₁V₁ /V₂
P₂ = 752 torr. 275 mL / 750 mL
P₂ = 206800 torr. mL /750 mL
P₂ = 275.7 torr
For argon:
P₁V₁ = P₂V₂
P₂ = P₁V₁ /V₂
P₂ = 722 torr. 475 mL / 750 mL
P₂ = 342950 torr. mL /750 mL
P₂ = 457.2 torr
Total pressure = P(helium) + P ( argon)
Total pressure = 275.7 torr + 457.2 torr
Total pressure = 732.9 torr
We have a 275-mL flask with helium at 752 torr and a 475-mL flask with argon at 722 torr. If both flasks are connected, the partial pressure of helium will be 276 torr, the partial pressure of argon will be 457 torr and the total pressure will be 733 torr.
We have 2 flasks:
A 275-mL flask contains pure helium at a pressure of 752 torr. A 475-mL flask contains pure argon at a pressure of 722 torr.If the two flasks are connected through a stopcock and the stopcock is opened, the final volume will be the sum of the initial volumes.
[tex]V_2 = 275mL + 475 mL= 750 mL[/tex]
Assuming ideal behavior and constant temperature, we can calculate the final partial pressure of each gas using Boyle's law.
[tex]P_1 \times V_1 = P_2 \times V_2[/tex]
Helium[tex]P_2 = \frac{P_1 \times V_1}{V_2} = \frac{752 torr \times 275mL}{750 mL} = 276torr[/tex]
Argon[tex]P_2 = \frac{P_1 \times V_1}{V_2} = \frac{722 torr \times 475mL}{750 mL} = 457torr[/tex]
Total pressureThe total pressure will be the sum of the partial pressures.
[tex]P = pHe + pAr = 276 torr + 457torr = 733torr[/tex]
We have a 275-mL flask with helium at 752 torr and a 475-mL flask with argon at 722 torr. If both flasks are connected, the partial pressure of helium will be 276 torr, the partial pressure of argon will be 457 torr and the total pressure will be 733 torr.
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What is the specific heat capacity of a metal if it requires 177.5 J to change the temperatures of 15.0g of the metal from 25.00 degree celcius to 34 degree celcius
Answer:
The specific heat capacity of a metal is 1.31 J/g°C = C
Explanation:
A classical excersise of calorimetry to apply this formula:
Q = m . C . ΔT
177.5 J = 15 g . C (34°C - 25°C)
177.5 J = 15g . 9°C . C
177.5 J /15g . 9°C = C
1.31 J/g°C = C
Final answer:
To find the specific heat capacity of the metal, the heat energy absorbed is divided by the product of mass and temperature change, which yields a specific heat capacity of 1.315 J/g\u00b0C.
Explanation:
To calculate the specific heat capacity of a metal with the given data, we can use the formula:
q = m \\cdot c \\cdot \\Delta T,
where q is the heat energy absorbed (in joules), m is the mass of the substance (in grams), c is the specific heat capacity (in J/g\u00b0C), and \\Delta T is the change in temperature (in degrees Celsius).
Rearranging the formula to solve for c gives:
c = q / (m \\cdot \\Delta T)
Substituting the given values:
q = 177.5 J,
m = 15.0 g,
\\Delta T = 34\u00b0C - 25\u00b0C = 9\u00b0C.
Therefore:
c = 177.5 J / (15.0 g \\cdot 9\u00b0C)
c = 177.5 J / 135 g\u00b0C
c = 1.315 J/g\u00b0C
The specific heat capacity of the metal is 1.315 J/g\u00b0C.
For a molecule with the formula AB2, the molecular shape is ________. For a molecule with the formula AB2, the molecular shape is ________. linear or T-shaped trigonal planar linear or bent linear or trigonal planar T-shaped
Final answer:
For a molecule with the formula AB2, if there are no lone pairs on the central atom, the molecular shape is linear, as in BeH2 or CO2. If one lone pair exists, it creates a bent or V-shaped structure, seen in molecules like SO2. Other geometries like trigonal planar or T-shaped are not possible for AB2.
Explanation:
For a molecule with the formula AB2, there are potentially different shapes that the molecule can have, depending on the presence and arrangement of lone pairs of electrons on the central atom. If there are no lone pairs on the central atom, the molecule would have a linear shape, with the two B atoms and the A atom arranged in a straight line. This can be seen in examples like BeH2 and CO2, where the central atom contains only two electron groups, and they orient themselves as far apart as possible—180° apart.
However, if there is one lone pair on the central atom, the shape will be bent, or V-shaped. This is because the molecule can be thought of as a trigonal planar structure with one vertex missing due to the lone pair. The lone pair takes up additional space, causing the bond angle to be less than 120°, as seen in molecules like SO2.
Lastly, with additional lone pairs, other geometries like trigonal planar can be eliminated. The molecule AB2 could also not exhibit a T-shaped geometry as that would require more than three electron groups on the central atom.
Chlorine can be prepared in the laboratory by the reaction of manganese dioxide with hydrochloric acid. true or false
Answer:
The given statement is true.
Explanation:
Chlorine gas is prepared by heating manganese dioxide with hydrochloric acid.T he reaction takes place in two steps
1) Reaction between manganese dioxide and HCl gives manganese(II) chloride along with water and nascent oxygen.
[tex]MnO_2+2HCl\rightarrow MnCl_2+H_2O+O[/tex]...[1]
2) Then this nascent oxygen formed in above reaction oxidizes HCl into water and chlorine gas.
[tex]2HCl+O\rightarrow Cl_2+H_2O[/tex]..[2]
So , the net chemical reaction comes out to be:
[tex]MnO_2+4HCl\rightarrow MnCl_2+H_2O+Cl_2[/tex]
Answer the following questions: On a 10-fold dilution of a weak acid, the pH will ___________________. On a 10-fold dilution of a buffered solution, the pH will ______________. If one adds a small amount of strong base to a buffered solution, the pH will _______________. Can you make a buffer using a strong acid? Explain. How can you adjust the pH of a buffer solution? Explain.
Answer:
Increase; remain constant, remain constant; No; by adjusting the acid:base ratio of the buffer.
Explanation:
On a 10-fold dilution of a weak acid, the pH will INCREASE and that is because strong acids are not found in buffers, therefore, diluting a strong acid reduces the amount of hydrogen ions,H^+ present, consequently increasing the pH.
On a 10-fold dilution of a buffered solution, the pH will REMAIN CONSTANT because diluting a buffer does not affect the pH of the buffer.
If one adds a small amount of strong base to a buffered solution, the pH will REMAIN CONSTANT because the buffer will equalize the strong base, however, the pH may increase just a little.
One can not make a buffer solution using a strong acid because Buffers are composed of a weak acid and its conjugate base or a weak base and its conjugate acid, and weak acids or bases only dissociate partially. Strong acids dissociate completely, they overpower the reaction and move the reaction to completion.
pH of a buffer solution can be adjusted using by adjusting the acid:base ratio of the buffer.
Final answer:
Diluting a weak acid increases its pH, while a buffered solution maintains a consistent pH upon dilution or the addition of a small amount of strong base. Buffers cannot be made with strong acids, and adjusting a buffer's pH involves altering the weak acid to conjugate base ratio.
Explanation:
Changes in pH with Dilution and Additions:
On a 10-fold dilution of a weak acid, the pH will increase, because the concentration of hydrogen ions decreases, making the solution less acidic.On a 10-fold dilution of a buffered solution, the pH will remain relatively constant. This stability is due to the presence of both a weak acid and its conjugate base which can absorb added acids or bases without significantly changing the pH.If one adds a small amount of strong base to a buffered solution, the pH will increase slightly. However, due to the buffering action, this change is much less than it would be in an unbuffered solution.One cannot make a buffer using a strong acid because strong acids fully dissociate in water, and a buffer relies on the equilibrium between a weak acid and its conjugate base to maintain pH. To adjust the pH of a buffer solution, one can vary the ratio of the weak acid to its conjugate base. The pH of a buffer is ideally maintained within ±1 unit of the pKa of the weak acid.
The synthesis of methanol from carbon monoxide and hydrogen gas is described by the following chemical equation:
CO(g)+2H2(g)?CH3OH(g)
The equilibrium constant for this reaction at 25 ?Cis Kc=2.3×104. In this tutorial, you will use the equilibrium-constant expression to find the concentration of methanol at equilibrium, given the concentration of the reactants.
The equilibrium-constant expression is a mathematical equation that can be rearranged to solve for any of the variables in it. Rearrange the equilibrium-constant expression to solve for [CH3OH].
Kc[CO][H2]^2
Suppose that the molar concentrations for CO and H2 at equilibrium are [CO] = 0.02 M and [H2] = 0.06 M.
Use the formula you found in Part B to calculate the concentration of CH3OH.
Express your answer to one decimal place and include the appropriate units.
Answer:
[CH3OH(g)] = 1.7 M
Explanation:
CO(g) + 2H2(g) ↔ CH3OH(g)∴ Kc(25°C) = 2.3 E4 = [CH3OH(g)] / [CO(g)]×[H2(g)]²
⇒ [CH3OH(g)] = Kc.[CO(g)][H2(g)]²
∴ [CO(g)] = 0.02 M
∴ [H2(g)] = 0.06 M
⇒ [CH3OH(g)] = (2.3 E4)(0.02)(0.06)²
⇒ [CH3OH(g)] = 1.7 M
Final answer:
To find the equilibrium concentration of methanol, the equilibrium-constant expression is rearranged and the given concentrations of reactants are plugged in, yielding an equilibrium concentration of methanol equal to 1.7 M.
Explanation:
To calculate the equilibrium concentration of methanol ([tex]CH_3OH[/tex]) using the equilibrium constant (Kc), we start by writing the equilibrium-constant expression for the reaction:
Kc = [[tex]CH_3OH[/tex]] / ([[tex]CO][H_2]_2[/tex])
Given that Kc = 2.3 × 104, [CO] = 0.02 M, and [[tex]H_2[/tex]] = 0.06 M, we can rearrange the expression to solve for [[tex]CH_3OH[/tex]]:
[[tex]CH_3OH[/tex]] = Kc × [CO] × [tex][H_2]_2[/tex]
Plug in the values:
[[tex]CH_3OH[/tex]] = 2.3 × 104 × 0.02 M × (0.06 M)2
Calculating the above expression gives us:
[[tex]CH_3OH[/tex]] = 2.3 × 104 × 0.02 × 0.0036 = 1.656 M
Rounding to one decimal place, the equilibrium concentration of methanol is 1.7 M.
An experiment reacts 20.4 g of zinc metal with a solution containing an excess of iron (III) sulfate. After the reaction, 10.8 grams of iron metal are recovered. What is the percent yield of the experiment?
Answer:
The answer to your question is 92.7%
Explanation:
Balanced Chemical reaction
3 Zn + Fe₂(SO₄)₃ ⇒ 2Fe + 3ZnSO₄
Molecular weight
Zinc = 65.4 x 3 = 196.2g
Iron (III) = 56 x 2 = 112 g
Proportions
196.2 g of Zinc ------------------ 112 g of Iron
20.4 g of Zinc ----------------- x
x = (20.4 x 112) / 196.2
x = 2284.8/196.2
x = 11.65 g of Iron
% yield = [tex]\frac{10.8}{11.65} x 100[/tex]
% yield = 0.927 x 100
% yield = 92.7
How does removing trees affect nitrogen cycling in a forest ecosystem?
Answer:
Deforestation can directly affect the nitrogen cycle within a forest ecosystem. It is because the nitrogen is used by the micro-organisms such as nitrogen fixing bacteria that helps in converting the atmospheric nitrogen into useful ammonia that are taken up by the plants, in order to carry out the process of photosynthesis.
By cutting down the trees and plants, these cycling of nitrogen will be disturbed and also these nitrogen containing articles will be eroded and eventually will mix up with the rivers and stream affecting the aquatic ecosystem.
Thus, by cutting down the trees, the nitrogen cycle will be disrupted in a forest ecosystem.
Which of the following processes have a ΔS > 0? A. N2(g) + 3 H2(g) → 2 NH3(g) B. Na2CO3(s) + H2O(g) + CO2(g) → 2 NaHCO3(s) C. CH3OH(l) → CH3OH(s) D. All of these processes have a ΔS > 0. E. CH4(g) + H2O (g) → CO(g) + 3 H2(g)
Answer:
ΔS > 0 only for choice E: CH4(g) + H2O (g) → CO(g) + 3 H2(g)
Explanation:
Our strategy in this question is to use the trend in entropies :
S (solids) less than S (liquids) less than S (gases)
Also we have to look for the molar quanties involved of each state and their change to answer the question:
A. N2(g) + 3 H2(g) → 2 NH3(g)
Here we have 4 moles gases going to 2 moles of products, so the change in entropy is negative.
B. Na2CO3(s) + H2O(g) + CO2(g) → 2 NaHCO3(s)
The change in entropy is negative since we have 2 mol gases in the reactants and zero in the products.
C. CH3OH(l) → CH3OH(s)
A liquid has a higher entropy than a solid so ΔS is negative
D. False see A,B,C
E. The change in moles of gases is 4 - 2= 2, therefore ΔS is greater than O.
The reaction CH4(g) + H2O (g) → CO(g) + 3 H2(g) will have ΔS > 0.
The term entropy refers to the degree of disorder of a system. Hence, the change in entropy is positive (greater than zero) when there is an increase in the degree of disorderliness of the system.
As such, the reaction;
CH4(g) + H2O (g) → CO(g) + 3 H2(g)will experience an increase in entropy since there is an increase in the number of molecules of gaseous species from left to right.
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You would like to induce a transversion mutation into a sequence of dna. Which type of chemical mutagen would give you the best chance of inducing the correct mutation without causing transition mutations as well?
Answer:
The type of chemical mutagen to choose depends on the intended effect. In this case, the best ones are acridines and nitrous acid.
Explanation:
Brenner et al. proposed that acridines induce mutations by causing deletions or additions of single base pairs during replication. Acridines bind to DNA by intercalation between adjacent base pairs. Acridines inactivate extracellular phage by photodynamic action but the necessary conditions for this killing
are avoided in the procedure for acridine-induced mutation of reproducing phage. The lack of reported acridine-induced mutation in organisms other than phage raises some questions as to the generality of its
mutagenesis, thus making it a good type of compounds to induce specific mutations.
In the other hand, nitrous acid deaminates the amino bases adenine, cytosine (and hydroxymethylcytosine) , and guanine in nucleic acids.
Analysis of the effect of differences of pH during nitrous acid treatment
of phage DNA showed that the rate of killing was affected similarly to
the rate of guanine deamination, and that the rates of induced r mutation was affected similarly to the rates of adenine and hydroxymethylcytosine deamination. Ascribing the induced mutations to deamination of adenine and cytosine is reasonable in terms of the hydrogen bonding of their products and the Watson-Crick base pairing schemes. Since this inorganic acid is molecule-specific, it would also be used to induce certain mutations in bacteria without causing transition mutations.
If the forces acting on an object are unbalanced, what will occur?
Constant speed
Change in mass
Constant velocity
Acceleration
Answer:
The answer is acceleration.
Explanation:
Acceleration- When it comes to science, Force is defined as a "push or pull" of an object with mass that causes it to change velocity.
Balanced Force- This occurs when two forces of the same mass or size are acting on a particular object in opposite direction. The object being acted upon could either stay in its place or move in a uniform speed and direction.
Unbalanced Force- This occurs when the forces applied are not equal and are of different direction. For example, a 55-kg person pulling a 30-kg cart. The cart will move to the direction of the pull.
Thus, when forces acting on an object are unbalanced, it causes the object to accelerate. This acceleration is directly proportional to the "net force", but is inversely proportional to the mass or size.
A net force is the total amount of force that is acting on the object.
Purification of chromium can be achieved by electrorefining chromium from an impure chromium anode onto a pure chromium cathode in an electrolytic cell. How many hours will it take to plate 11.0 kg of chromium onto the cathode if the current passed through the cell is held constant at 41.5 A? Assume the chromium in the electrolytic solution is present as Cr₃. ______ h.
Explanation:
It is given that mass is 11 kg. Convert mass into grams as follows.
[tex]11 kg \times \frac{1000 g}{1 kg}[/tex]
= 11000 g (as 1 kg = 1000 g)
Now, calculate the number of moles as follows.
No. of moles = [tex]\frac{\text{Mass of Cr}}{\text{Molar mass of Cr}}[/tex]
= [tex]\frac{11000 g}{52 g/mol}[/tex]
= 211.54 mol
For [tex]Cr^{3+}[/tex], 3 moles of electrons are required
Hence, [tex]3 \times 211.54 mol[/tex]
= 634.62 mol
As 1 mol of electrons contain 96500 C of charge. Therefore, charge carried by 634.62 mol of electrons will be calculated as follows.
Q = [tex]634.62 mol \times 96500 C/mol [/tex]
= [tex]61.24 \times 10^{6} C[/tex] of charge
We know that relation between charge, current and time is as follows.
Q = [tex]I \times t[/tex]
Current is given as 41.5 A and charge is calculated as [tex]61.24 \times 10^{6} C[/tex]. Therefore, calculate the time as follows.
Q = [tex]I \times t[/tex]
[tex]61.24 \times 10^{6} C = 41.5 A \times t[/tex]
t = [tex]1.47 \times 10^{6} sec[/tex]
As there are 3600 seconds in one 1 hour. Therefore, converting [tex]1.47 \times 10^{6} sec[/tex] into hours as follows.
[tex]\frac{1.47 \times 10^{6} sec}{3600 sec/hr}[/tex]
= 4.09 hr
Thus, we can conclude that it takes 4.09 hours to plate 11.0 kg of chromium onto the cathode if the current passed through the cell is held constant at 41.5 A.
The process of electrorefining chromium involves oxidation of Chromium III ions at anode and reduction at the cathode. The total charge required for this process can be calculated using Faraday's law, and the time required to pass this charge can be calculated using the formula Q/I. Therefore, it will take approximately 408 hours to plate 11kg of chromium onto the cathode with 41.5 A current.
Explanation:The process of electrorefining chromium involves two half-reactions at anode and cathode in which chromium is oxidized at the anode and is then reduced at the cathode. Specifically, Chromium III ion (Cr³+) is oxidized at the anode with the reaction Cr³+ (aq) + 3e-, and is then reduced at the cathode. The stoichiometry of this process requires three moles of electrons for each mole of chromium(0) produced. Given this stoichiometry and the current passed through the cell, we can calculate the time required to plate 11kg of chromium.
First, since the molar mass of chromium is approximately 52 g/mol, 11kg is equal to about 211.5 mol. This number of moles of chromium requires [tex]211.5 * 3 = 634.5[/tex] mol of electrons. One mol of electrons carries a charge of approximately 96485 Coulombs (C), so the total charge is approximately [tex]6.115 * 10^7 C.[/tex]
If this charge is being passed at 41.5 C/s, the time required to pass the total amount of charge can be calculated by the formula Q/I, where Q represents the total charge and I represents the current. Therefore, the time required to plate 11kg of chromium onto the cathode with 41.5 A current is approximately [tex]1.47 * 10^6[/tex] seconds which is approximately 408 hours.
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Which of the following observations indicates that an atom has neutrons?
A. Some uncharged particles are scattered by a beryllium atom when it hits a gold foil.
B. Some uncharged particles bounce back from a gold foil when it is bombarded with alpha particles.
C. A radiation with neutral particles is emitted when alpha particles strike beryllium atoms.
D. A radiation which attracts electrons is produced when a beryllium atom is bombarded with alpha particles.
C
When the alpha particle hits the beryllium atoms at high speeds, it splits the atomic nuclei hence causing the nuclei particles flying. When exposed to an electric field, the path of the proton is curved towards the negative pole while neutrons are unaffected.
Explanation:
Neutrons are found in the dense part of atoms (the nucleus) along with protons. Unlike protons, however, that are positively charged, neutrons are uncharged particles. Neutrons are important in the stability of the atomic nuclei because they ensure that the positively charged particles (protons), which are cramped together in a tight space, do not repel each other because like-charges repel.
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A particular solvent with ΔS∘vap=112.9J/(K⋅mol) and ΔH∘vap=38.0kJ/mol is being considered for an experiment. In the experiment, which is to be run at 75 ∘C, the solvent must not boil. Based on the overall entropy change associated with the vaporization reaction, would this solvent be suitable and why or why not?
Answer:
This solvent is not suitable because ΔS°vap > 0.
Explanation:
Let's consider a system at a higher temperature T1, and its surroundings at a lower temperature T2. Let's call q the heat that goes irreversible from the system to the surroundings:
ΔSsystem = -q/T1 (it's losing heat, so q must be negative)
ΔSsurroundings= q/T2
ΔSprocess = ΔSsystem + ΔSsurroundings
ΔSprocess = -q/T1 + q/T2
ΔSprocess = q*(1/T2 - 1/T1)
ΔSprocess = q*[(T1 - T2)/(T1*T2)]
As pointed above, T1> T2, so ΔSprocess > 0 and because of that, the reaction is spontaneous. It means that if ΔS°vap > 0, the solvent will vaporize. So, as we can notice, the solvent given is not suitable.
Final answer:
The overall entropy change for vaporization helps determine if a solvent is suitable for an experiment. A high value of entropy indicates increased disorder, making vaporization likely. In this case, with a high entropy of 112.9 J/(K⋅mol), the solvent's boiling at 75 ∘C may hinder its suitability for the experiment.
Explanation:
The overall entropy change associated with the vaporization reaction can be calculated considering the entropy of vaporization (ΔSvap) and the enthalpy of vaporization (ΔHvap) of the solvent. As stated in Trouton's rule, ΔSvap is approximately 10.5R, which is around 85-88 J/(mol K) for many liquids. In this case, with a ΔSvap of 112.9 J/(K⋅mol) and a ΔHvap of 38.0 kJ/mol, the high ΔSvap value indicates that the solvent has a highly disordered structure, making it likely to vaporize at the given temperature of 75 ∘C, hence making it unsuitable for the experiment.
A spectrophotometer measures the transmittance or the absorbance, or both, of a particular wavelength of light after it has passed through a liquid sample. Before the transmittance or absorbance of the sample is measured, a cuvette filled only with solvent, called the blank, is placed in the spectrophotometer and measured. Select the reason that, after the blank is measured, the cuvette must be placed in the spectrophotometer in the same orientation each time that it is used.
a. The spectrophotometer will break if the cuvette position is changed during the experiment.
b. The transmittance of the cuvette must be measured in the same place each time.
c. The cuvette will only fit into the spectrophotometer in one orientation.
d. The transmittance of the liquid must be measured in the same place each time.
Answer:
b. The transmittance of the cuvette must be measured in the same place each time.
Explanation:
When using a spectrophotometer, light passes not only through the liquid sample, it also passes through the cuvette. This means that each time a reading is made, you not only measure the transmittance/absorbance of the sample, but of the cuvette as well.
For this reason it's important that the reading of the cuvette's absorbance remains the same through all the process, so the answer is b), because different faces of the cuvette may have different absorbances.