Chemistry Chapter: Raoult's and Henry's Laws Quiz

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Questions and Answers

What is the expression for Henry's law in terms of solute molality?

pJ = xJp*J

pB = bBKJ

pB = bBKB (correct)

pJ = xJKA

What does Raoult’s law state regarding partial vapor pressure?

It relates partial vapor pressure to the solubility of gases.

It describes a curve for total pressure versus mole fraction.

It requires Henry's law constants for calculation.

It defines a straight line for each component in excess. (correct)

In which regions is Henry's law applicable?

Only at high mole fractions of solute.

At low mole fractions where the component behaves as the solute. (correct)

In regions above the boiling point of the solvent.

Only in non-ideal solutions.

Which of the following is a Henry’s law constant for acetone?

24.5 kPa Signup and view all the answers

What type of relationship is plotted in Raoult's and Henry's laws?

Partial vapor pressure versus mole fraction Signup and view all the answers

What is the partial molar volume of ethanol in a 50 percent by mass ethanol/water solution?

56.4 cm3 mol−1 Signup and view all the answers

How does the chemical potential of a substance in a mixture generally vary?

It varies with composition. Signup and view all the answers

What is the limiting partial molar volume of MgSO4 in water?

−1.4 cm3 mol−1 Signup and view all the answers

What effect does adding 1 mol of MgSO4 to a large volume of water have on the volume of the mixture?

It decreases the volume by 1.4 cm3. Signup and view all the answers

What is the mass density of the 50 percent by mass ethanol/water solution at 25 °C?

0.914 g cm−3 Signup and view all the answers

In the context of chemical potentials, what contributes to the total Gibbs energy of a mixture?

The contributions of all substances present. Signup and view all the answers

What happens to the structure of water when MgSO4 is added?

The structure collapses slightly. Signup and view all the answers

How do partial molar quantities differ from molar volumes?

Partial molar volumes can be negative. Signup and view all the answers

What factor contributes to the changes in volume when adding water to pure ethanol compared to pure water?

The identity of the surrounding molecules Signup and view all the answers

What is the partial molar volume of pure water at 25 °C when 1 mole is added?

18 cm³ mol⁻¹ Signup and view all the answers

How does the chemical potential of a substance in a mixture relate to concentration?

It is a logarithmic function of its concentration. Signup and view all the answers

What happens to the hydrogen bonding network of water when it is mixed with ethanol?

It weakens due to ethanol molecules surrounding water. Signup and view all the answers

What is the impact of adding 1 mole of H2O to a large volume of pure ethanol?

It increases the volume by only 14 cm³. Signup and view all the answers

Why is it not necessary to know about solutions that react together when evaluating mixtures?

Understanding non-reactive mixtures is sufficient. Signup and view all the answers

What is the significance of phase diagrams in discussing liquid crystals?

They provide insight into the properties of mixtures. Signup and view all the answers

What can be concluded about the volume increase when adding a substance to a solvent?

The identity of the solvent affects the volume change. Signup and view all the answers

What represents the numerical value of the molar volume of pure water at 298 K?

18.079 cm3 mol−1 Signup and view all the answers

Which equation represents the relationship implied by the Gibbs–Duhem equation for two components?

nAdµA + nBdµB = 0 Signup and view all the answers

In the expression for the molar volume of salt B, which component represents the variable z?

Molality of K2SO4 Signup and view all the answers

What is the correct form of the equation to find vA using integration?

vA = v*A - ∫(nB/nA) dvB Signup and view all the answers

Which of the following describes the thermodynamic characteristic of G?

It is a state function. Signup and view all the answers

When using the Gibbs–Duhem equation, what is held constant during the process?

Temperature and pressure Signup and view all the answers

How is the molar volume of water (vA) expressed in relation to the variable z?

vA = 18.079 - 0.0464z^2 + 0.0859z^3 Signup and view all the answers

What do the terms nA and nB represent in the Gibbs–Duhem equation?

Number of moles of components A and B Signup and view all the answers

What happens to the total entropy during the mixing of perfect gases?

It increases at all compositions. Signup and view all the answers

What does the equation µA(1) = µA(g) + RT ln pA represent?

The chemical potential of A in the liquid phase. Signup and view all the answers

What is the expression for the change in mixing entropy (∆mixS) when equal amounts of perfect gases are mixed?

∆mixS = −nR { 12 ln 12 + 12 ln 12 } Signup and view all the answers

What is the expected result when one gas disperses into another?

Increase in entropy. Signup and view all the answers

In the equation ∆mixS = nR ln 2, what does 'n' represent?

The total moles of gas present. Signup and view all the answers

If a solute is introduced to the liquid, how is the chemical potential of A in the liquid affected?

It is reduced due to solute presence. Signup and view all the answers

What does the term 'equilibrium' refer to in the context of gas and solvent?

The vapor and solvent are in balance, meaning no net change. Signup and view all the answers

Given the values, what is the calculated change in mixing entropy for 1 mol of each gas species?

+11.5 J K−1 Signup and view all the answers

What does the equation for partial molar volume suggest about the relationship between volume and concentration?

Volume changes in a non-linear fashion with concentration Signup and view all the answers

What is the approximate partial molar volume of K2SO4 at its highest concentration shown in the figure?

18.078 cm3 mol–1 Signup and view all the answers

Which variable is NOT present in the simplified equation for partial molar volume?

n (amount of substance) Signup and view all the answers

In the provided second equation, $ ext{µ = µ}_0 + RT ext{ln} p $ represents what aspect of the system?

Chemical potential as a function of pressure Signup and view all the answers

What does the term 'pA + pB = p' in the context indicate?

The total pressure is the sum of partial pressures Signup and view all the answers

Which statement about the graph in Figure 5A.5 is accurate?

The partial molar volume of K2SO4 decreases as b increases Signup and view all the answers

How does the partial molar volume of water change according to the figure?

It decreases with increasing concentration of K2SO4 Signup and view all the answers

What is the significance of the term 'RT ln p' in the equation regarding potential?

It accounts for entropic contributions to chemical potential Signup and view all the answers

Which concentration variable is used in the partial molar volume equation?

molality Signup and view all the answers

What is the initial value of the partial molar volume of water indicated in the figure?

18.079 cm3 mol–1 Signup and view all the answers

Study Notes

Focus 5: Simple Mixtures

Mixtures are crucial in chemistry, either as the reaction material or as the reaction itself.
Topics cover the rich physical properties of mixtures and expression in thermodynamic terms.

5A: Thermodynamic Description of Mixtures

Introduces chemical potential as a partial molar quantity.
Explores how chemical potential describes mixture properties.
Equilibrium principle: Species chemical potential is the same in every phase.
Raoult's and Henry's laws used to express substance chemical potential via mole fraction.

5B: The Properties of Solutions

Applies chemical potential to solution properties' effects.
Properties affected by solute: Lowered solvent vapour pressure, elevated boiling point, depressed freezing point, and osmotic pressure.
"Regular solutions" diverge from ideal solution properties.

5C: Phase Diagrams of Binary Systems: Liquids

Phase diagrams summarize mixture equilibrium.
Diagrams depict liquid-vapor coexistence, liquid/liquid coexistence, and phase transitions.
Raoult's law used to determine vapor pressures.
Ideal solutions characterized by linear vapor pressure-composition relationships.
Phase diagrams are useful tools for distillation.
Azeotropes are mixtures whose components do not separate during vaporization.

5D: Phase Diagrams of Binary Systems: Solids

Diagrams show solid-liquid phase transitions.
Eutectics represent compositions with the lowest melting points.
Eutectic mixtures freeze at a constant temperature.
Incongruent melting occurs when a compound decomposes into its components during melting.

5E: Phase Diagrams of Ternary Systems

Ternary systems have three components.
Phase diagrams are typically triangular.
Tie lines connect compositions of coexisting phases.
Plait points are special compositions where coexisting phases have identical properties.
Phase diagrams illustrate conditions for different phase stability.

5F: Activities

Activities quantify effective concentration for real solutions.
Extend ideal solution expressions to include deviations from ideality.
Activity coefficients correct for non-ideal behavior.
Activity coefficients approach 1 as concentration approaches zero.
Deals with cases where activities of both solvent and solute need to be considered.

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Description

Test your knowledge on Raoult's and Henry's laws with this quiz! Explore key concepts such as partial vapor pressure, solute molality, and the effects of solutes in mixtures. Understand the fundamental relationships that describe the behavior of solutions and their chemical potentials.