Chapter 13 Homework
13.1 Types of Mixtures
1. Classify the following as either a heterogeneous or homogeneous mixture, and explain your answers:
a) orange juice
b) tap water
2. a) What are substances called whose water solutions conduct electricity?
b) Why does a saltwater solution conduct elelctricity?
c) Why does a sugar water solution not conduct electricity?
3. Describe one way to prove that a mixture of sugar and water is a solution and that a mixture of sand and water is not a solution.
4. Label the solute and solvent in each of the following:
a) 14 karat gold;
b) water vapor in air;
c) carbonated, or sparkling, water
d) hot tea.
13.2 Tyndall Effect
1. a) What is the Tyndall effect?
b) Identify one example of this effect.
2. Given an unknown mixture consisting of two or more substances, explain one technique that could be used to determine whether that mixture is a true solution, a colloid, or a suspension.
13.3 The Solution Process
Factors Affecting the Rate of Dissolution
1. Why would you expect a packet of sugar to dissolve faster in hot tea than in iced tea?
2. a) Explain how you would prepare a saturated solution of sugar in water;
b) How would you then make it a supersaturated solution?
3. What visible evidence indicates that a solution is saturated?
4. What is an unsaturated solution?
1. Explain why ethanol will dissolve in water and carbon tetrachloride will not.
2. When a solute molecule is solvated, is heat released or absorbed?
3. If a warm bottle of soda and a cold bottle of soda are opened, which will effervesce more and why?
4. a) What is solution equilibrium?
4. b) What factors determine the point at which a given solute-solvent combination reaches equilibrium?
5. What condition(s) must be specified when expressing the solubility of a substance?
6. What rule of thumb is useful for predicting whether one substance will dissolve in another?
7. How does pressure affect the solubility of a gas in a liquid?
8. Based on Figure 13-15, determine the solubility of each of the following in grams of solute per 100. g of water:
a) NaNO3 at 100 C;
b) KNO3 at 600 C
c) NaCl at 500 C
13.5 Heats of Solution
1. The heat of solution for AgNO3 is +22.8 kJ/mol:
a) Write the equation that represents the dissolution of AgNO3 in water;
b) Is the dissolution process endothermic or exothermic?
c) is the crystallization process endothermic or exothermic?
d) As AgNO3 dissolves, what change occurs in the temperature of the solution?
e) If the system comes to equilibrium, if the solution is heated, how will the rates of dissolution and crystallization be affected. Explain why.
2. If a saturated solution of KNO3 in 100. g of water at 600 C is cooled to 200 C, approximately how many grams of the solute will precipitate out of the solution? (Use table 13-4)
13.6 Concentration of Solutions - Molarity
1. What is the molarity of a solution composed of 5.85 g or potassium iodide, KI, dissolved in enough water to make 0.125 L of solution? Soln
2. How many moles of H2SO4 are present in 0.500 L of a 0.150 M H2SO4 solution?soln
3. What volume of 3.00 M NaCl is needed for a reaction that requires 146.3 g of NaCl? soln
4. Five grams of sugar, C12H22O11, are dissolved in water to make 1 L of solution. What is the concentration of this solution expressed as molarity? soln
5. What is the molarity of a solution made by dissolving 26.42 g of (NH4)2SO4 in enough water to make 0.050 L of solution? soln
13.7 Concentration of Solutions - Molality
1. What is the molality of a solution composed of 255g of acetone, (CH3)2CO, dissolved in 200. g of water? soln
2. What quantity, in grams, of methanol, CH3OH, is required to prepare a 0.244 m solution in 400. g of water? soln
3. How many grams of AgNO3 are needed to prepare a 0.125 m solution in 250. g of water? soln
4. What is the molality of a solution containing 18.2 g of HCl and 250. g of water? soln
5. How many grams of solute will be needed to prepare a 4.50 m solution of H2SO4 in 1.000 kg of water? soln
6. How many grams of solute will be needed to prepare a 1.5 m solution of HNO3 in 2.00 kg of water? soln
7. How many kg of water must be added to 75.5 g of Ca(NO3)2 to prepare a 0.500 m solution? soln