Chemistry Chapter on Mixtures

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Questions and Answers

What type of mixture is a solution classified as?

Heterogeneous mixture

Suspension

Colloid

Homogeneous mixture (correct)

Which statement correctly describes the particles in a colloid?

Individual atoms or ions

Soluble ions only

Small, uniform molecules

Macromolecules or aggregations of small molecules (correct)

Which factor does not affect the solubility of a solute?

Color of the solute (correct)

Temperature of the solvent

Pressure applied to the solute

Nature of the solute and solvent

What does the term 'like dissolves in like' imply?

Substances with similar intermolecular forces can dissolve in each other Signup and view all the answers

When a solution forms, what happens to the attractions between solute and solvent?

They replace solute-solute and solvent-solvent attractions Signup and view all the answers

Based on the data provided, what mass percentage of the solution is made up of macromolecules?

23% Signup and view all the answers

What is typically the most abundant component in a solution?

Solvent Signup and view all the answers

What is the nature of a colloid compared to a solution?

Colloids are heterogeneous mixtures with visually distinct phases. Signup and view all the answers

Which type of forces allow NaCl to dissolve in polar solvents?

Ion-dipole forces Signup and view all the answers

What happens during the first step of the dissolution process?

Solute particles separate from each other. Signup and view all the answers

What type of forces orient water molecules around an ion?

Ion-dipole forces Signup and view all the answers

Which statement is true regarding the hydration of ions?

It results in the release of heat. Signup and view all the answers

What is the overall enthalpy change when a solute and solvent mix?

It can be less than ΔHsolute + ΔHsolvent. Signup and view all the answers

Which statement about alcohols is true?

The –OH group of an alcohol is polar. Signup and view all the answers

Predict the solubility of sodium chloride in 1-propanol compared to methanol.

More soluble in methanol Signup and view all the answers

Which compound is likely to dissolve better in 1-propanol compared to methanol?

A non-polar solute due to dispersion forces Signup and view all the answers

How do alcohols interact with water?

Through hydrogen bonding Signup and view all the answers

Which of the following correctly describes the role of ethylene glycol in a solution?

It can form hydrogen bonds with both itself and water. Signup and view all the answers

Why are hydrogen bonds in water more effective than dipole-induced dipole forces with hexane?

Hydrogen bonds can replace interactions in solute better. Signup and view all the answers

Which alcohol has the highest solubility in water?

Methanol Signup and view all the answers

Which statement is correct about the endothermic nature of the dissolution process?

Both solute and solvent separations are endothermic. Signup and view all the answers

What is the primary interaction between hexane and the hydrocarbon portion of alcohols?

Dipole-induced dipole forces Signup and view all the answers

Which solvent would ethylene glycol be least soluble in?

Hexane Signup and view all the answers

What general principle is described in the phrase 'like dissolves like'?

Polar solutes dissolve in polar solvents. Signup and view all the answers

What is the molality of H2O2 in the solution?

12.6 m Signup and view all the answers

How many moles of H2O are present in the solution?

3.88 mol Signup and view all the answers

What is the mole fraction of H2O2 in the solution?

0.185 Signup and view all the answers

What is the volume of the solution in mL given the mass and density?

90.1 mL Signup and view all the answers

What is the molarity of H2O2 in the solution?

9.79 M Signup and view all the answers

What is the primary reason for the higher solubility of most solids at elevated temperatures?

Higher temperatures increase the kinetic energy of the solvent particles. Signup and view all the answers

Which statement best describes a supersaturated solution?

It contains more solute than the equilibrium concentration and is unstable. Signup and view all the answers

Why does the solubility of gases decrease as temperature increases?

Higher temperatures increase the energy of gas particles, causing them to escape. Signup and view all the answers

What happens to the solubility of gases when pressure is increased?

Gases become more soluble as more gas particles collide with the liquid surface. Signup and view all the answers

What is the relationship between the partial pressure of a gas and its solubility in a solution?

Solubility is directly proportional to the partial pressure. Signup and view all the answers

Which of the following describes a saturated solution?

It contains the maximum amount of dissolved solute at a given temperature. Signup and view all the answers

For NaCl, what is true about its enthalpy of solution compared to its entropy change during dissolution?

The enthalpy of solution is larger than the entropy change, leading to NaCl's non-solubility. Signup and view all the answers

What characterizes an unsaturated solution?

It contains less than the equilibrium concentration of dissolved solute. Signup and view all the answers

Study Notes

Solutions and Colloids

Solutions are homogeneous mixtures with a single phase, while colloids are heterogeneous mixtures with distinct phases.
Solutions contain individual atoms, ions, or small molecules, whereas colloids consist of macromolecules or aggregations of small molecules.

Composition of Cellular Solutions

Water makes up approximately 70% of cell mass.
Other solutes in cells include ions (1%), sugars (3%), amino acids (0.4%), lipids (2%), and macromolecules (23%).
Solubility is influenced by the interaction between solute and solvent, summarized by the expression "like dissolves in like."

Intermolecular Forces

Various types of intermolecular forces include ion-dipole (40-600 kJ/mol), hydrogen bonding (10-40 kJ/mol), and dispersion forces (0.05-40 kJ/mol).
Solvent-solvent and solute-solute attractions are replaced by solute-solvent attractions during solution formation, requiring similar intermolecular forces.

Alcohols and Solubility

Alcohols feature a polar –OH group, which allows them to interact with water and hydrocarbons through different intermolecular forces.
Solubility of alcohols in water decreases with increased hydrocarbon chain length, while solubility in hexane increases.

Solvation Process

Solvation, or hydration in water, involves surrounding solute particles with solvent molecules.
Hydration of ions is exothermic, as it involves strong ion-dipole attractions.

Entropy and Solutions

Entropy (S) measures a system's energy dispersion and freedom of motion, with gases displaying the highest entropy.
Solutions generally have higher entropy compared to pure solutes and solvents; entropy increases favor the dissolution process.

Types of Solutions

A saturated solution contains the maximum dissolved solute possible at a given temperature, while unsaturated solutions can accommodate more solute.
Supersaturated solutions are unstable and contain excess solute, which crystallizes upon disturbance.

Effect of Temperature and Pressure on Solubility

Solubility of solids typically increases with temperature; gas solubility decreases as temperature rises.
Gas solubility increases with pressure, governed by the equation S_gas = k_H × P_gas (Henry's Law).

Example Calculations

Given a solution with 30.0 g H2O2 and 70.0 g H2O, molality can be calculated, resulting in 12.6 m H2O2.
Conversions from mass percentage to mole fraction and from mass percentage/density to molarity can be performed to determine the concentration of solutions.

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Description

This quiz covers key concepts of solutions and colloids in chemistry. Understand the differences between homogeneous and heterogeneous mixtures, and recognize the types of particles involved in each. Perfect for students looking to reinforce their knowledge of mixtures.