UNIT 12 Solutions. Homework. CRHS Academic Chemistry. Due Date Assignment On-Time (100) Late (70) Warm-Up

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1 Name Period CRHS Academic Chemistry UNIT 12 Solutions Homework Due Date Assignment On-Time (100) Late (70) Warm-Up EC Notes, Homework, Exam Reviews and Their KEYS located on CRHS Academic Chemistry Website:

2 Page 2 of 12 Unit 12 HW WARM-UPS Day 1 Day 2 Day 3 Day 4 Day 5 Day 6

3 Extra Credit Unit 12 HW Page 3 of 12

4 Page 4 of 12 Unit 12 HW 12.1 WATER AND TYPES OF SOLUTIONS 1. Water is a polar molecule. What does polar mean? 2. Water molecules are held together by ( STRONG / WEAK ) hydrogen bonds. 3. Why does water have a relatively high boiling point? 4. Solid water (ice) takes on a 3 dimensional shape that contains much more empty space than water. How does this explain why ice floats in water? 5. What does like dissolves like mean? 6. What is a solution? 7. What is an aqueous solution? 8. To make chocolate milk, you stir 2 spoons of chocolate syrup into 2 cups of milk. CIRCLE the solvent and BOX the solute.

5 Unit 12 HW Page 5 of For each action, write whether it would increase (I), decrease (D), or have no effect (N), on the solubility of the solid solute. a. Decreasing the temperature of the solution b. Decreasing the pressure over the solution c. Adding a nonpolar solute to a polar solvent 10. For each action, write whether it would increase (I), decrease (D), or have no effect (N), on the solubility of the gaseous solute. a. Placing a soda in the refrigerator b. Increasing the temperature of the solution c. Decreasing the pressure around the solution 11. For each action, write whether it would increase (I), decrease (D), or have no effect (N), on the RATE of solubility of the solute. a. Using a packet of sugar instead of a sugar cube b. Heating up a sugar and tea solution c. Stirring a solid solute into a solution of water 12. Circle the below compounds that are electrolytes. CCl 4 SF 6 NaCl BaO PH 3 K 2SO List two pairs of liquids that YOU know of that are miscible. 14. List two pairs of liquids that are immiscible.

6 Solubility, grams of solute per 100 grams of water Page 6 of 12 Unit 12 HW 12.2 SOLUBILITY GRAPHS AND CURVES 200 Temperature - Solubility Relationships KNO CsCl NaNO 3 NaC 2 H 3 O RbCl 120 LiCl KI CuSO 4 NH 4 Cl 60 KCl 40 NaCl Temperature ( C) Use the graph to answer all questions. 1. How much KNO 3 dissolves in 100 g of water that is 30 C? 2. How much KNO 3 dissolves in 100 g of water that is 70 C? 3. How many grams of KCl will dissolve in 200 g of water at 45 C? 4. How many grams of NaNO 3 are required to make a saturated solution in g of water at 70 C? 5. How much NH 4Cl will dissolve in 50.0 grams of water at 70 C? 6. At what temperature will a saturated solution of SO 2 hold 20 grams of solute? 7. As the temperature of the solution increases, the solubility of LiCl ( INCREASES / DECREASES ). 8. The solubility of KI ( INCREASES / DECREASES ) with a decrease in temperature.

7 Unit 12 HW Page 7 of Circle the correct description of each solution. a g of KCl in g of water at 80 C ( Unsaturated / Saturated / Supersaturated ) b. 135 g of KI in g of water at 90 C ( Unsaturated / Saturated / Supersaturated ) c g of NaNO 3 in 50.0 g of water at 10 C ( Unsaturated / Saturated / Supersaturated ) d g of NaCl in g of water at 80 C ( Unsaturated / Saturated / Supersaturated ) grams of NaNO 3 are in 100 ml of water at 40.0 C. If more NaNO 3 is added, will it dissolve? ( YES / NO ) 11. At what temperature is the solubility of NaNO 3 equal to the solubility of KNO 3?

8 Page 8 of 12 Unit 12 HW 12.3 MOLARITY AND DILUTIONS grams of CsCl is placed in grams of water at 25.0 C. Will all of the CsCl dissolve? ( YES / NO ) 2. What is the molarity of 1.5 L of solution that contains 0.50 mol MgCl 2? 3. What is the molarity of 250 ml of solution that contains 0.70 mol NaCl? 4. How many moles of solute are present in 1.5 L of 0.24 M Na 2SO 4? 5. How many grams of CaCl 2 are in 250 ml of 2.0 M CaCl 2 solution? 6. What is the molarity of a solution made by dissolving 80.0 grams of NaOH in one liter of solution?

9 Unit 12 HW Page 9 of If I have 0.60 moles of sodium iodide how much water would it take to make a 0.25 M solution? 8. How many ml of initial solution of 2.00 M MgSO 4 would you need to prepare ml of M MgSO 4? 9. If you need 250 ml of 0.20 M NaCl, what volume of a 1.0 M NaCl, solution do you need? 10. You dilute 50.0 ml of 5.0 M NaCl to make a ml of solution, what is the molarity of the dilute solution? 11. How many liters of 15 M sodium nitrate are needed make 225 ml of a M solution? 12. If you had 43.0 ml of a 3.00 M hydrochloric acid solution and you dilute it to 500 ml, what is the new molarity?

10 Page 10 of 12 Unit 12 HW 12.4 COLLIGATIVE PROPERTIES 1. Why does a solution have a lower vapor pressure than the pure solvent of that solution? 2. Would a dilute or a concentrated sodium fluoride solution have a higher boiling point? Explain. 3. Would the freezing point of 0.5 mol NaCl in 100 ml water be higher or lower than 0 C? Explain. 4. An aqueous solution freezes at 2.47 C. Will this solution s boiling point be greater than, the same as, or less than 100 C. 5. Why would calcium chloride (CaCl 2) spread on icy roads be more effective at melting ice than sodium chloride (NaCl)? 6. Compared to pure water, an aqueous solution of potassium bromide has a boiling point, freezing point, and a vapor pressure. (Insert higher or lower into each blank.)

11 7. What properties do solutions and colloids have in common? Unit 12 HW Page 11 of What properties do solutions and suspensions have in common? 9. What properties do colloids and suspensions have in common? 10. What is the Tyndall effect?

12 Page 12 of 12 Unit 12 HW