A mysterious white powder could be powdered sugar (C12H22O11), cocaine (C17H21NO4), codeine (C18H21NO3), norfenefrine (C8H11NO2), or fructose (C6H12O6). When 82 mg of the powder is dissolved in 1.50 mL of ethanol (d = 0.789 g/cm3, normal freezing point −114.6 ∘C, Kf = 1.99 ∘C/m), the freezing point is lowered to −115.5 ∘C. What is the identity of the white powder?
Answers
Norfenefrine (C₈H₁₁NO₂).
Further explanationWe will solve a case related to one of the colligative properties, namely freezing point depression.
The freezing point of the solution is the temperature at which the solution begins to freeze. The difference between the freezing point of the solvent and the freezing point of the solution is called freezing point depression.
[tex]\boxed{ \ \Delta T_f = T_f(solvent) - T_f(solution) \ } \rightarrow \boxed{ \ \Delta T_f = K_f \times molality \ }[/tex]
Given:
A mysterious white powder could be,
powdered sugar (C₁₂H₂₂O₁₁) with a molar mass of 342.30 g/moles, cocaine (C₁₇H₂₁NO₄) with a molar mass of 303.35 g/moles, codeine (C₁₈H₂₁NO₃) with a molar mass of 299.36 g/moles, norfenefrine (C₈H₁₁NO₂) with a molar mass of 153.18 g/moles, or fructose (C₆H₁₂O₆) with a molar mass of 180.16 g/moles.When 82 mg of the powder is dissolved in 1.50 mL of ethanol (density = 0.789 g/cm³, normal freezing point −114.6°C, Kf = 1.99°C/m), the freezing point is lowered to −115.5°C.
Question: What is the identity of the white powder?
The Process:
Let us identify the solute, the solvent, initial, and final temperatures.
The solute = the powderThe solvent = ethanolThe freezing point of the solvent = −114.6°CThe freezing point of the solution = −115.5°CPrepare masses of solutes and solvents.
Mass of solute = 82 mg = 0.082 gMass of solvent = density x volume, i.e., [tex]\boxed{ \ 0.789 \ \frac{g}{cm^3} \times 1.50 \ cm^3 = 1.1835 \ g = 0.00118 \ kg \ }[/tex]We must prepare the solvent mass unit in kg because the unit of molality is the mole of the solute divided by the mass of the solvent in kg.
The molality formula is as follows:
[tex]\boxed{ \ m = \frac{moles \ of \ solute}{kg \ of \ solvent} \ } \rightarrow \boxed{ \ m = \frac{mass \ of \ solute \ (g)}{molar \ mass \ of \ solute \times kg \ of \ solvent} \ }[/tex]
Now we combine it with the formula of freezing point depression.
[tex]\boxed{ \ \Delta T_f = K_f \times \frac{mass \ of \ solute \ (g)}{molar \ mass \ of \ solute \times kg \ of \ solvent} \ }[/tex]
It is clear that we will determine the molar mass of the solute (denoted by Mr).
We enter all data into the formula.
[tex]\boxed{ \ -114.6^0C - (-115.5^0C) = 1.99 \frac{^0C}{m} \times \frac{0.082 \ g}{Mr \times 0.00118 \ kg} \ }[/tex]
[tex]\boxed{ \ 0.9 = \frac{1.99 \times 0.082}{Mr \times 0.00118} \ }[/tex]
[tex]\boxed{ \ Mr = \frac{0.16318}{0.9 \times 0.00118} \ }[/tex]
We get [tex]\boxed{ \ Mr = 153.65 \ }[/tex]
These results are very close to the molar mass of norfenefrine which is 153.18 g/mol. Thus the white powder is norfenefrine.
Learn moreThe molality and mole fraction of water https://brainly.com/question/10861444 About the mass and density of ethylene glycol as an antifreeze https://brainly.com/question/4053884 About the solution as a homogeneous mixture https://brainly.com/question/637791Keywords: a mysterious white powder, sugar, cocaine, codeine, norfenefrine, fructose, the solute, the solvent, dissolved, ethanol, normal freezing point, the freezing point depression, the identity
The identity of the white powder is [tex]\boxed{\text{norfenefrine}(\text{C}_{8}\text{H}_{11}\text{NO}_{2})}[/tex] .
Further Explanation:
Colligative properties
These are the properties that depend on the number of solute particles and not on their mass or identities. Following are the four colligative properties:
1. Relative lowering of vapor pressure
2. Elevation in boiling point
3. Depression in freezing point
4. Osmotic pressure
The temperature where a substance in its liquid form is converted into the solid state is known as freezing point. Freezing point depression is a colligative property because it depends on the number of moles of solute particles.
The expression for the freezing point depression is as follows:
[tex]\Delta\text{T}_\text{f}=\text{K}_\text{f}\,\text{m}[/tex] …… (1)
Here,
[tex]\Delta\text{T}_\text{f}[/tex] is the depression in freezing point.
[tex]\text{K}_\text{f}[/tex] is the cryoscopic constant.
m is the molality of the solution.
The formula to calculate the density of substance is as follows:
[tex]\text{Density of substance}=\dfrac{\text{Mass of substance}}{\text{Volume of substance}}[/tex] …… (2)
Rearrange equation (2) for the mass of substance.
[tex]\text{Mass of substance}=(\text{Density of substance })(\text{Volume of substance})[/tex] …… (3)
The volume of the substance is to be converted into . The conversion factor for this is,
[tex]1\,\text{ml}=1\,\text{cm}^3[/tex]
Therefore the volume of the substance can be calculated as follows:
[tex]\begin{aligned}\text{Volume}&=(1.50\,\text{mL})\left(\frac{1\,\text{cm}^3}{1\,\text{mL}}\right)\\&=1.50\,\text{cm}^3\end{aligned}[/tex]
Substitute [tex]1.50\,\text{cm}^3[/tex] for the volume of substance and [tex]0.789\,\text{g/gm}^3[/tex] for the density of the substance in equation (3) to calculate the mass of solvent.
[tex]\begin{aligned}\text{Mass of solvent}&=\left(\dfrac{0.789\,\text{g}}{1\,\text{cm}^3}\right)(1.50\,\text{cm}^3)\\&=1.1835\,\text{g}\end{aligned}[/tex]
This mass is to be converted into kg. The conversion factor for this is,
[tex]1\,\text{g}=10^{-3}\,\text{kg}[/tex]
Therefore the mass of solvent can be calculated as follows:
[tex]\begin{aligned}\text{Mass of solvent}&=(1.1835\,\text{g})\left(\dfrac{10^{-3}\,\text{kg}}{1\,\text{g}}\right)\\&=0.0011835\,\text{kg}\end{aligned}[/tex]
The mass of solute is to be converted into g. The conversion factor for this is,
[tex]1\,\text{mg}=10^{-3}\,\text{g}[/tex]
Therefore the mass of solute can be calculated as follows:
[tex]\begin{aligned}\text{Mass of solute}&=(82\,\text{mg})\left(\dfrac{10^{-3}\,\text{g}}{1\,\text{g}}\right)\\&=0.082\,\text{g}\end{aligned}[/tex]
The freezing point depression can be calculated as follows:
[tex]\begin{aligned}\Delta\text{T}_\text{f}&=-114.6\,^\circ\text{C}-(-115.5\,^\circ\text{C})\\&=0.9\,\circ\text{C}\end{aligned}[/tex]
The formula to calculate the molality of solution is as follows:
[tex]\text{Molality of solution}=\dfrac{\text{Amount (mol) of solute}}{\text{Mass (kg) of solvent}}[/tex] …… (4)
The formula to calculate the amount of solute is as follows:
[tex]\text{Amount of solute}=\dfrac{\text{Mass of solute}}{\text{Molar mass of solute}}[/tex] …… (5)
Incorporating equation (5) into equation (4),
[tex]\text{Molality of solution}=\dfrac{\text{Mass of solute}}{(\text{Mass of solvent})(\text{Molar mass of solute})}[/tex] …… (6)
Incorporating equation (6) into equation (1),
[tex]\Delta\text{T}_\text{f}=\text{k}_\text{f}\left(\dfrac{\text{Mass of solute}}{(\text{Mass of solvent})(\text{Molar mass of solute})}\right)[/tex] …… (7)
Rearrange equation (7) to calculate the molar mass of solute.
[tex]\text{Molar mass of solute}=\dfrac{\text{k}_\text{f}}{\Delta\text{T}_\text{f}}\left(\dfrac{\text{Mass of solute}}{\text{Mass of solvent}}\right)[/tex] …… (8)
Substitute [tex]1.99\,^\circ\text{C/m}[/tex] for [tex]\text{k}_\text{f}[/tex], [tex]0.9\,^\circ\text{C}[/tex] for [tex]\Delta\text{T}_\text{f}[/tex], 0.082 g for the mass of solute and 0.0011835 kg for the mass of solvent in equation (8).
[tex]\begin{aligned}\text{Molar mass of solute}&=\left(\dfrac{1.99}{0.9}\right)\left(\dfrac{0.082}{0.0011835}\right)\\&=153.199\,\text{g/mol}\\&=\approx153.2\,\text{g/mol}\end{aligned}[/tex]
The molar mass of powdered sugar is 342.3 g/mol.
The molar mass of cocaine is 303.4 g/mol.
The molar mass of codeine is 299.4 g/mol.
The molar mass of norfenefrine is 153.2 g/mol.
The molar mass of fructose is 180.2 g/mol.
The calculated molar mass of solute is similar to that of norfenefrine. So the identity of the white powder is norfenefrine.
Learn more:
What is the concentration of alcohol in terms of molarity? https://brainly.com/question/9013318 What is the molarity of the stock solution? https://brainly.com/question/2814870Answer details:
Grade: Senior School
Chapter: Solutions
Subject: Chemistry
Keywords: colligative properties, depression in freezing point, cryoscopic constant, freezing point, 153.199 g/mol, norfenefrine.
Related Questions
How many grams nano3 add to 500g of h20 prepare solution .5 molal nano3?
Answers
m(H₂O) = 500 g · 1 kg/1000 g = 0,5 kg.
b(solution) = 0,500 m = 0,500 mol/kg.
m(NaNO₃) = ?
b(solution) = n(NaNO₃) ÷ m(H₂O).
n(NaNO₃) = 0,500 mol/kg · 0,5 kg.
n(NaNO₃) = 0,25 mol.
m(NaNO₃) = n(NaNO₃) · M(NaNO₃).
m(NaNO₃) = 0,25 mol · 85 g/mol.
m(NaNO₃) = 21,25 g.
Match the each term with its definition. 1) reaction coordinate a) the higher point on the energy curve 2) δg° b) the plot of the reaction progress as a function of time 3) δg‡ c) the free energy of the reaction
Answers
1) reaction coordinate will match with
B)the plot of the reaction progress as a function of time.
as the reaction coordinate is the progress of a reaction from the reactants to products with different transition states in between. The X-axis: which has the reaction progress reflects the progressive chemical changes and the formation of bond and the bond breakage as S (the energy associated with the reactant) is changing and converting to P ( the energy that associated with the product).Actually, it has no relation to time.Rather partially formation of bonds and breaking of bond reaction steps.
2)ΔG° will match with
c) the free energy of the reaction.
As it is simply defined as the Gibbs free energy and is also known as a free enthalpy, it is used to calculate the maximum of reversible work performed by the thermodynamic system when the temperature and the pressure are constant.
3)ΔG will match with
A) the higher point of the energy curve.
when ΔG = ΔGproduct - ΔGreactant
and It is simply defined as the change in free energy. It reflects nothing about the speed of the reaction. ΔG+ indicates that the reaction is endergonic and energy goes from reactants to products.and ΔG- become negative when the reaction goes to a lower energy state and it indicates then that the reaction is exergonic.
Write and balance the chemical equation for the reaction between carbon monoxide, co(g), and oxygen to form carbon dioxide, co2(g). use only integers (not fractions) and be sure to include the states of matter.
Answers
CO + O2 → CO2
this is not a balanced equation.
as the reactants C = 1 and O= 3
and the products C= 1 and O=2
so we put 1/2 O2 instead of O2 to balance the no. of O atom on
each side.
CO + 1/2 O2 → CO2 to get the integers number we will multiply by 2
the final balanced equation is:
2CO(g) +O2(g) → 2CO2(g)
So we finally have
at the reactants side C atom = 2 & O= 4
at the products side C atom = 2 & O = 4
The balanced chemical equation for the reaction between carbon monoxide (CO) and oxygen (O₂) to form carbon dioxide (CO₂) is 2 CO(g) + O₂(g) → 2 CO₂(g), adhering to the law of conservation of mass.
Explanation:The reaction between carbon monoxide (CO) and oxygen (O₂) to form carbon dioxide (CO₂) can be represented by the following balanced chemical equation:
2 CO(g) + O₂(g) → 2 CO₂(g)
In balancing this equation, it is important to ensure that the number of each type of atom on the reactants side is equal to the number on the products side. Here, we have two carbon atoms and two oxygen atoms from the CO molecules and two oxygen atoms from the O₂ molecule, giving us a total of four oxygen atoms on the reactants side, which balance with the four oxygen atoms in the two CO₂ molecules on the right side of the equation.
This reaction demonstrates the law of conservation of mass, where the mass of the reactants equals the mass of the products. In this case, the coefficients used are the smallest possible whole numbers that maintain this balance.
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moves river of ice fresh water made of fallen snow snow compressed to ice This is a list of features of a(n) A) glacier. B) ice age. C) iceberg. D) continent.
Answers
The answer is A. Glacier
If a propane heater burns 38.95 g C3H8, it consumes 38.95 mol C3H8. 0.8830 mol C3H8. 1 mol C3H8. 44.10 mol C3H8.
Answers
Here's how the answer was generated:
We do know that all the choices are in moles, in that case, we divide the 38.95 g of propane (C3H8) by the molar mass which is:
C = 12.01
H = 1.01
C3H8 = 3 * 12.01 + 8 * 1.01 = 44.11
Divide 38.95 g by 44.11 g/mol and the answer will be 0.8830 mol C3H8.
Answer:
Option-2 (0.8830 mol C₃H₈) is the correct answer.
Solution:
In statement we are given with the amount of propane gas and are asked to find out the moles for given mass.
As we know mass is related to moles as follow,
Moles = Mass / M.mass ----- (1)
Data Given:
Moles = ??
Mass = 38.95 g
M.mass = (C)3 + (H)8 = (12)3 + (1)8 = 36 + 8 = 44 g/mol
Putting values in equation 1,
Moles = 38.95 g / 44 g/mol
Moles = 0.8854 Moles
What is the smallest particle of an element that still retains all the properties of the element? a compound a mineral an atom an isotope
Answers
The basic building block of chemistry is known as the atom. The smallest particle of an element that still retains all the properties of the element is known as the atom. The correct option is C.
What is an atom?The atom can be considered as the basic building blocks of matter which possess the properties of the chemical element. An atom don't exist independently, instead they form ions and molecules which in turn combine in large numbers to form matter.
An atom is an indivisible particle and it contains the sub-atomic particles like protons, electrons and neutrons. The positively charged particles are called protons, the negatively charged particles are called electrons. The neutrons are chargeless particles.
All atoms of the same element are identical but different elements have different types of atoms. The chemical reactions occur when the atoms are rearranged.
Thus the correct option is C.
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dentify the molecule with the highest boiling point.
CHCl3
OF2
NH3
C6H6
Answers
Answer: Option (c) is the correct answer.
Explanation:
A molecule which has hydrogen bonding will have the highest boiling point. So, out of the given options only [tex]NH_{3}[/tex] will have hydrogen bonding.
Whereas in [tex]CHCl_{3}[/tex] there will be dipole-dipole interactions and no hydrogen bonding within the molecule.
In [tex]OF_{2}[/tex] and [tex]C_{6}H_{6}[/tex], there will be dipole-dipole interaction in both the molecules.
Thus, we can conclude that [tex]NH_{3}[/tex] will have the highest boiling point.
Minerals form from bodies of water by the process of _____. precipitation melting cooling condensation
Answers
Minerals form from water bodies by the process of [tex]\boxed{{\text{precipitation}}}[/tex].
Further Explanation:
The formation of minerals takes place in several ways. The mineral formation depends on the physical and chemical conditions. These conditions include temperature, pressure, pH, and time.
Precipitation
It is a process by which the dissolved minerals get free from water and as a result deposits are formed. It occurs when dissolved substances come out of water. Minerals form when precipitation takes place in aqueous solutions and from gaseous emissions as in case of volcanic eruptions.
Melting
The process that results in the conversion of any substance from a solid state to the liquid state is known as melting. Another term for this process is fusion.
Cooling
The process of removal of heat by lowering the temperature of any substance is known as cooling.
Condensation
This phase transition occurs when a substance is converted from its gaseous state to the liquid state. Variations in temperature and pressure are done in order to achieve this phase change.
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Answer details:
Grade: Senior School
Chapter: Phase transition
Subject: Chemistry
Keywords: minerals, precipitation, cooling, melting, condensation, pH, temperature, time, pressure, substance, phase transition, gaseous state, liquid state, heat, dissolved minerals, water bodies.
In a molecule of methane (ch4), what type of bond joins the carbon atom to each of the hydrogen atoms?
Answers
Approximately how many moles of boron make up 1.20 × 10^24 atoms of boron?
A. 7.22 × 10^47 moles
B. 6.02 × 10^23 moles
C. 5.00 moles
D. 1.99 moles
Answers
x mol = 1.2 * 10^24
x = 1.2 * 10^24/6.02 * 10^23
x = 1.993 mol.
Answer: D <<<<<======
Explain why c6h5ch2ch2br is not formed during the radical bromination of c6h5ch2ch3. select the single best answer.
Answers
The radical bromination reaction of C₆H₅CH₂CH₃ is performed through a mechanism in which radical reactions are involved. This compound is an alkylbenzene compound, and the carbon that is more reactive towards radical bromination is the carbon bonded to the aromatic ring because in the reaction mechanism the intermediaries are stabilized by resonance in the aromatic ring.
A terminal substitution will not occur because substitution there will not be stabilized by resonance. The compound that will be formed in this reaction would be:
C₆H₅CH₂CH₃ + Br₂ → C₆H₅CH₂(Br)CH₃ + HBr
Final answer:
C6H5CH2CH2Br is not formed during the radical bromination of C6H5CH2CH3 because the intermediate benzyl radical, formed at the carbon adjacent to the aromatic ring, is much more stable than the primary radical needed for the other product. Selectivity is due to bromine's preference for stable radicals, supported by Hammond's postulate.
Explanation:
The reason why C6H5CH2CH2Br is not formed during the radical bromination of C6H5CH2CH3 involves the relative stability of the radical intermediate. Radical bromination tends to occur at the position that forms the most stable radical, which for a benzyl compound is the carbon atom directly adjacent to the aromatic ring. The radical formed at this position, a benzyl radical, is highly stabilized by resonance. In contrast, the radical that would be required to form C6H5CH2CH2Br is a primary radical, which is less stable and thus less likely to form. This selectivity is due to the fact that bromine radicals are relatively selective and prefer to abstract hydrogen atoms from positions that lead to more stable radical intermediates. Moreover, Hammond's postulate suggests that since the radical formation with bromine is endothermic, the transition state will more closely resemble the stable radical intermediate, leading to more selective radical formation.
You are given a crushed sample that is a mixture of limestone (caco3), lime (cao), and sand. the calcium carbonate, limestone, is the only material present in the material that will decompose when heated. you subject a 6.4734 g sample of the mixture to strong heating and after the sample reaches a constant mass (no more mass is lost with additional heating), the sample has a final weight of 4.3385 g. what is the percentage of calcium carbonate present in the original mixture? (f.wt. caco3 = 100.1)
Answers
Chemical reaction: CaCO₃ → CaO + CO₂.
m₁(sample) = 6,4734 g.
m₂(sample) = 4,3385 g.
m(CO₂) = m₁(sample) - m₂(sample).
m(CO₂) = 6,4734 g - 4,3385 g.
m(CO₂) = 2,1349 g.
n(CO₂) = m(CO₂) ÷ M(CO₂).
n(CO₂) = 2,1349 g ÷ 44 g/mol.
n(CO₂) = 0,0485 mol.
From chemical reaction: n(CO₂) : n(CaCO₃) = 1 : 1.
n(CaCO₃) = 0,0485 mol.
m(CaCO₃) = 0,0485 mol · 100,1 g/mol.
m(CaCO₃) = 4,854 g.
percentage of calcium carbonate = 4,854 g ÷ 6,4734 g · 100%.
percentage of calcium carbonate = 75%.
H2+I2= 2HI+3 kcal Based on the reaction given above, as the temperature decreases, the formation of the reactants will: A. decrease B. increase C. remained consistent D. indeterminate
Answers
Decrease
Explanation:
The reaction given is an exothermic reaction. This means that the heat is a product.
At equilibrium, the rate of forward reaction is equal to the rate of backward reaction.
Now, decreasing the temperature means that the concentration of the products will decrease.
As a result, the equilibrium will shift to the right leading to the formation of more products in order to reach equilibrium again.
This means that the formation of the reactants will decrease.
Hope this helps :)
the answer is A: decrease
The ph of 0.015 m hno2 (nitrous acid) aqueous solution was measured to be 2.63. what is the value of pka of nitrous acid?
Answers
HNO₂(s) ⇄ H⁺(aq) + NO₂⁻(aq)
According to the equation, an acid constant has the following form:
Ka = [H⁺] × [NO₂⁻ ] / [HNO₂]
From pH, we can calculate the concentration of H⁺ and NO₂⁻:
[H⁺] = 10^-pH = 10^-2.63 = 0.00234 M = [NO₂⁻]
Now, the acid constant can be calculated:
Ka = 0.00234 x 0.00234 / 0.015 = 3.66 x 10⁻⁴
And finally,
pKa = -log Ka = 3.44
Draw the acetal produced when ethanol adds to ethanal.
Answers
Acetal is produced when one molecule of aldehyde (in this reaction ethanal) and two molecules of alcohols (in this reaction ethanol) react. Hemiacetal is produced when one molecule of aldehyde and one molecule of alcohol react. Acetals are stable compared to hemiacetals.
Explanation:
Acetals are geminal diethers derivatives of aldehyde formed by the addition to equivalent molecules of an alcohol and removal of water.
When ethanol is added to the ethanal in acidic medium:
Ethanal + Ethanol → Hemiacetal
Hemiacetal + Ethanol → Acetal
Acetal produced when ethanol is added to ethanal are given in the image attached.
Hexanal would be soluble in water? True or false?
Answers
Answer:
False.
Explanation:
Hexanal is a non-polar compound while water is a polar solvent.
We have the role "Like dissolves like".
So, hexanal is insoluble in water.
Scientists often investigate alternative explanations for the data and observations presented, even once a hypothesis has been tested and supported through an experiment. This investigation of alternative explanations ...
Answers
This is your answer
Answer:
Strengthens the evidence and support for a scientific theory.
Explanation:
Hello,
Scientific method provides a compelling tool scientists use to both develop and demonstrate new theories. As it involves both the observation and experimentation towards a specific subject of matter, it turns out convenient to consider alternative explanations substantiating such subject of matter in light of obtaining a more precise explanation for it. In such a way, this investigation of alternative explanations strengthens the evidence and support for a scientific theory.
Best regards.
In an experiment, you combine 83.77 g of iron with an excess of sulfur and then heat the mixture to obtain iron(III) sulfide. 2Fe(s) + 3S(s) → Fe2S3(s) What is the theoretical yield, in grams, of iron(III) sulfide?
Answers
Fe = 55.845 g/mol
S = 32.065 g/mol
Fe2S3 = 207.9 g/mol
Next, convert Fe mas to moles.
83.77 g / 55.845 g/mol = 1.5 mol Fe
Us the stoichiometry (mole ratio) to get to moles product.
2 Fe reactants makes 1 Fe2S3 product
1.5 mol Fe * (1 Fe2S3 / 2 Fe) = 0.75 mol Fe2S3
Now multiply buy the Fe2S3 molar mass to get its weight in grams.
0.75 mol Fe2S3 * 207.9 g/mol = 155.925 g
This is the amount you should theoretically obtain using that much iron.
The theoretical yield of iron (II) sulfide would be 155.92 g
Theoretical yieldIt is the total stoichiometric product from a reaction.
From the equation of the reaction:
2Fe(s) + 3S(s) → Fe2S3(s)
The mole ratio of Fe to Fe2S3 is 2:1
Mole of 83.77 g Fe = 83.77/55.85
= 1.4999 moles
Equivalent mole of Fe2S3 = 1.4999/2
= 0.75 moles
Mass of 0.75 mole Fe2S3 = 0.75 x 207.9
= 155.92 g
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If kc = 7.04 × 10-2 for the reaction: 2 hbr(g) ⇌h2(g) + br2(g), what is the value of kc for the reaction: 1/2 h2(g) + 1/2 br2 ⇌hbr(g)
Answers
So Kc = [H2] [Br2] / [HBr]^2
7.04X10^-2 = [H2][Br] / [HBr]^2
at the second reaction when 1/2 H2(g) + 1/2 Br2 (g) ⇄ HBr
Its Kc value will = [HBr] / [H2]^1/2*[Br2]^1/2
we will make the first formula of Kc upside down:
1/7.04X10^-2 = [HBr]^2/[H2][Br2]
and by taking the square root:
∴ √(1/7.04X10^-2)= [HBr] / [H2]^1/2*[Br]^1/2
∴ Kc for the second reaction = √(1/7.04X10^-2) = 3.769
The value of Kc for the second reaction is mathematically given as
Kc' = 3.769
What isthe value of Kc for the second reaction?
Question Parameters:
kc = 7.04 × 10-2 for the reaction
2 hbr(g) ⇌h2(g) + br2(g)
1/2 h2(g) + 1/2 br2 ⇌hbr(g)
Generally, the equation for the reaction is mathematically given as
2HBr(g) ⇄ H2(g) + Br2(g)
Therefore
Kc = [H2] [Br2] / [HBr]^2
7.04X10^-2 = [H2][Br] / [HBr]^2
Upon final reaction
Kc' = [HBr] / [H2]^1/2*[Br2]^1/2
Hence
[tex]\sqrt{(1/7.04X10^-2)}= [HBr] / [H2]^1/2*[Br]^1/2}\\\\Kc' = \sqrt{(1/7.04X10^-2)[/tex]
Kc' = 3.769
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What mass of potassium hydroxide is formed when 8.2 g of potassium oxide is added to 1.3 g of water? answer key?
Answers
K20 + H20 = 2KOH
According to the equation we have following stoichiometric ratio:
n(K2O) : n(H20) = 1 : 1
From it, we can conclude that K2O and water react in same mass ratio.
Now, we have to determine limiting reagent (the one who determines how much the product will arise).
n(K2O)=m/M=8.2/94=0.09 mole
n(H20)=m/M=1.3/18=0.07 mole
So, there are fewer moles of H2O and it will determine the amount of the product.
n(H2O) : n(K0H) = 1 : 2
n(K0H)=n(H2O) x 2 = 0.17 mole
Finally, the was of KOH is:
m(KOH)= n x M = 0.17 x 56= 9.5 g
For a particular first-order reaction, it takes 3.0 minutes for the concentration of the reactant to decrease to 25% of its initial value. what is the value for rate constant (in s-1) for the reaction?
Answers
For a first-order reaction, the rate constant can be determined using the concentration of the reactant at a given time. In this case, the rate constant is 0.25 s^-1.
Explanation:A first-order reaction is one in which the rate of reaction is directly proportional to the concentration of the reactant. The rate law expression for a first-order reaction is given by rate = k[A], where [A] is the concentration of the reactant and k is the rate constant.
In this case, the concentration of the reactant decreases to 25% of its initial value in 3.0 minutes. We can use this information to determine the rate constant (k).
25% of the initial concentration corresponds to 0.25 times the initial concentration, so the concentration at that time is 0.25[A]. We can substitute this value into the rate law expression and solve for k:
0.25[A] = k[A]
0.25 = k
Therefore, the value for the rate constant (k) for the reaction is 0.25 s-1.
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To find the rate constant (k) for a first-order reaction, we can use the half-life formula. The given information states that it takes 3.0 minutes for the concentration of the reactant to decrease to 25% of its initial value. By substituting these values into the equation, we can find the rate constant.
Explanation:To determine the rate constant (k) for the first-order reaction, we can use the formula for the half-life of a first-order reaction. The half-life is the amount of time it takes for the concentration of the reactant to decrease to half of its initial value. In this case, it takes 3.0 minutes for the concentration to decrease to 25% of its initial value, which is equivalent to one half-life.
The formula for the first-order half-life is: t1/2 = ln(2)/k
Since the concentration decreases to 25% of its initial value after one half-life, we can use this information to solve for k:
25% = (1/2) * 100% = e-kt1/2
ln(1/2) = -k * t1/2
k = -ln(1/2) / t1/2
Substituting the given values, we have:
k = -ln(1/2) / 3.0 minutes
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pls help me!!
Which of the following is a large body in space that orbits a star and does not produce its own light?
Moon
Planet
Sun
Universe
Answers
What is the acid-base equilibrium reaction between ClO– and H2O.
Answers
ClO⁻ is base in this chemical reaction and water is acid. According Brønsted–Lowry acid–base theory base is compound that attracts protons (H⁺) and acid (in this chemical reaction water) gives protons.
Ke = [OH⁻] · [HClO] / [ClO⁻].
[OH⁻] - equilibrium concentration.
A student is given two metal cubes that look similar. the first had an edge length of 1.05 cm and a mass of 14.32 g, while the other had an edge length of 2.66 cm and a mass of 215.3 g. how can the student determine if these two cubes of metal are the same material using only the given data?
Answers
Object One
Volume = 1.05^3 cm^3 = 1.158 cm^3
Mass = 14.32
Density = mass / volume
Density = 14.32 / 1.158
Density = 12.37 g/cm^3
Object Two
The density for this object is found exactly the same way. Just use the numbers given to you.
Density = 11.43 grams / cm^3
Conclusion
Since you trust your gives to 3 places, it does not look like these two cubes are made of the same material.
Answer: Not the same material <<<===
The value densities of cube-1 and cube-2 are not at all similar which means that both the cubes are made up of different materials.
Explanation:
Mass and volume are extensive properties of the matter which change with change in the size of matter. But density is an intensive property of a matter which is independent of the size and shape of the matter.The density of the matter is given by:[tex]Density=\frac{Mass}{Volume}[/tex]
So one can compare of values of densities of two unknowns to determine whether both are materials the same or not.Given:
Two different cubes, one with an edge length of 1.05 cm and mass of 14.32 g, and the other cube have an edge length of 2.66 cm and mass of 215.3 g.
To find:
Whether two cubes are of the same material or not.
Solution:
The edge length of the cube-1 = l = 1.05 cm
The volume of cube-1 =v
[tex]v=l^3=(1.05 cm)^3=1.16 cm^3[/tex]
Th mass of cube-1 = m = 14.32 g
The density of the cube-1 =d
[tex]d=\frac{m}{v}\\d=\frac{14.32 g}{1.16 cm^3}=12.3 g/cm^3[/tex]
The edge length of the cube-2 = l' = 2,66 cm
The volume first cube-2 =v'
[tex]v'=l'^3=(2.66 cm)^3=18.8 cm^3[/tex]
Th mass of cube-2 = m = 215.3g
The density of the cube-2 =d'
[tex]d'=\frac{m'}{v'}\\d'=\frac{215.3g}{ 18.8cm^3}=11.4g/cm^3[/tex]
The value density of cube-1 is different from that of cube-2, not at all similar which means that both the cubes are made up of different materials.
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The reaction of 0.779 g K with O2 forms 1.417 g potassium superoxide, a substance used in self-contained breathing devices. Determine the formula for potassium superoxide.
Answers
K - 0.779 g / 39 g/mol
= 0.02 mol
the mass of O₂ reacted = 1.417 g - 0.779 g = 0.638 g
O₂ moles = 0.638 g / 32 g/mol
= 0.02 mol
the number of both K and O₂ moles reacted are equal
therefore stoichiometry of K to O₂ reacted are 1:1
then the formula of potassium superoxide is KO₂
Final answer:
The correct formula for potassium superoxide formed when 0.779 g of potassium reacts with an excess of oxygen to form 1.417 g of the compound is[tex]KO_{2}[/tex]
Explanation:
The formula for potassium superoxide can be determined by considering the mass of potassium reacted and the mass of the resultant compound formed. In this case, 0.779 grams of potassium reacts with oxygen to form 1.417 grams of potassium superoxide. Knowing that the potassium has fully reacted and become part of the potassium superoxide, we can deduce that the difference in mass (1.417 g - 0.779 g = 0.638 g) must be due to the oxygen present in the compound.
The simplest ratio between potassium (K) and oxygen (O) that could form a compound would be a 1:1 ratio, which gives us KO. However, based on the provided information, potassium superoxide has a different stoichiometry where 1 mol of potassium reacts with oxygen to form a compound with the formula [tex]KO_{2}[/tex], which is a superoxide. This means there are two oxygen atoms for every potassium atom in the compound.
Therefore, the correct formula for potassium superoxide, as formed in the reaction with an excess of oxygen, is [tex]KO_{2}[/tex].
What products are formed from monochlorination of (2r)−2−bromobutane at c1 and c4? draw the products using skeletal structures?
Answers
From monochlorination of (2R)−2−bromobutane at C4 is formed (2R)-3-bromo-1-chlorobutane.
According to Cahn-Ingold-Prelog rules, the priority of halogen substituents decreases in the following sequence:
-I > -Br > -Cl > -F
According to the rule, chlorine has priority over bromine, so the configuration changes at C1 substitution.
How many neutrons are found in Cr-54
Answers
=54-24
=30
So the answer is 30 neutrons
Answer:
30
Explanation:
To find out the neutron number of an element we must first know what the mass value of that element is and the value of the atom number of that element. To find out these values, just look for the element in the periodic table. Once discovered simply subtract the values using the formula:
No. of neutrons = mass - atom number.
In the case of Cr, the mass is 54, while the atom number is 24. So we can find the number of neutrons.
Cr Neutrons = 54-24 = 30
Consider the reaction a + b c +
d. at biochemical equilibrium (25°c, ph of 7), the concentration of a is 0.2 m, the concentration of b is 0.2 m, the concentration of c is 0.8 m, and the concentration of d is 0.8 m. calculate δg and δg° ′ under these conditions.
Answers
now we need to get Δ G°, we can get it from this formula:
ΔG° = - RT㏑K(eq)
when we have R = 8.315 J/mol°K and T in Kelvin = 25+273 = 298
so we need to get the K(eq) from this formula:
K(eq) = concentration of products / concentration of reactants
= [ C] [ D] / [A] [B]
= (0.8*0.8) / (0.2*0.2) = 16
by substitution in ΔG° formula:
∴ ΔG° = - 8.315 * 298 *㏑(16) = -6870 Jmol^-1 /1000 = - 6.87 KJ mol^-1
Write the chemical reaction that is responsible for the ph of a buffer which contains nh3 and nh4cl. write the reaction in such a way that is appropriate for a ka.
Answers
The pH of a buffer containing NH3 and NH4Cl is determined by the equilibrium between NH4+ and NH3 in water, with the reaction NH4+ (aq) + H2O(l) → H3O+ (aq) + NH3(aq). The reaction demonstrates the action of the ammonium ion as a weak acid, and its Ka is calculated using the Ka = Kw/Kb relationship. The chloride ion does not undergo significant hydrolysis, so it does not affect the pH of the buffer.
Explanation:The chemical reaction responsible for the pH of a buffer containing NH3 (ammonia) and NH4Cl (ammonium chloride) involves the equilibrium between NH4+ and NH3 in water:
NH4+ (aq) + H2O(l) ⇒ H3O+ (aq) + NH3(aq)
This represents the dissociation of the ammonium ion, which is a weak acid, in water to produce hydronium ions (H3O+) and ammonia. Since ammonia is a weak base, the corresponding acid dissociation constant (Ka) can be calculated using the relation Ka = Kw/Kb, where Kw is the ion product of water and Kb is the base dissociation constant of ammonia.
The chloride ion, being the conjugate base of the strong acid hydrochloric acid (HCl), does not undergo significant hydrolysis in water:
Cl-(aq) + H2O(l) → HCl(aq) + OH−(aq)
Since HCl is a strong acid, the equilibrium constant (Ka) for its conjugate base, Cl-, is essentially zero, which means Cl- does not affect the buffer solution's pH appreciably.
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Which of the following is a part of a land based carbon cycle ?coral reefs
Crab shells
Trees
Whales
Answers
Corals extract dissolved carbon dioxide from the ocean to secrete their hard rocky structures.
Crab shells and other marine animals with shells have their bodies incorporated into the seafloor when they die. The sea floor eventually gets subducted where it melts. The carbon present here gets back into the atmosphere via volcanic eruptions.
Answer:
c
Explanation: