1. Solutions Review Spring Final Exam

2. Definitions Solution -Solution - homogeneous mixture Solvent Solvent - present in greater amount Solute Solute - substance being dissolved

3. Definitions Solution -Solution - homogeneous mixture Solvent Solvent - present in greater amount Solute Solute - substance being dissolved

4. soluble: “will dissolve in” miscible: refers to two liquids that mix evenly in all proportions -- e.g., food coloring and water

5. Factors Affecting the Rate of Dissolution 1. temperature 2. particle size 3. mixing 4. nature of solvent or solute With more mixing, rate As temp., rate As size, rate We can’t control this factor.

6. Solubility vs. Temperature Timberlake, Chemistry 7 th Edition, page 297 KI NaNO 3 KNO 3 Na 3 PO 4 NaCl Temperature ( o C) Solubility (g solute / 100 g H 2 O) 200 180 160 140 120 100 80 60 40 20 0 406080100

7. Gas Solubility CH 4 O2O2 CO He Temperature ( o C) Solubility (mM) 2.0 1.0 01020304050 Higher Temperature …Gas is LESS Soluble

8. Solubility Temp. ( o C) Solubility (g/100 g H 2 O) KNO 3 (s) KCl (s) HCl (g) SOLUBILITY CURVE unsaturated: sol’n could hold more solute; saturated: sol’n has “just right” amt. of solute; supersaturated: sol’n has “too much” solute dissolved in it; how much solute dissolves in a given amt. of solvent at a given temp. below the line on the line above the line sudden stress causes this much ppt

9. Describe each situation below. (A) Per 100 g H 2 O, 100 g NaNO 3 @ 50 o C. (B) Cool sol’n (A) very slowly to 10 o C. (C) Quench sol’n (A) in an ice bath to 10 o C. unsaturated; all solute dissolves; clear sol’n. supersaturated; extra solute remains in sol’n; still clear saturated; extra solute (20 g) can’t remain in sol’n and becomes visible

10. Concentration A measure of the amount of solute dissolved in a certain amount of solvent. Concentrated solution has a large amount of solute. Dilute solution has a small amount of solute Separate from Saturated / unsaturated

11. Molarity The number of moles of solute in 1 Liter of the solution. M = moles/Liter What is the molarity of a solution with 2.0 moles of NaCl in 4.0 Liters of solution.

12. Molarity What is the molarity of a solution with 3.0 moles dissolved in 250 mL of solution. 12 M

13. Making solutions 10.3 g of NaCl are dissolved in a small amount of water then diluted to 250 mL. What is the concentration? 0.70 M

14. Dilution Adding solvent to a solution

15. Dilution The number of moles of solute doesn’t change if you add more solvent. The moles before = the moles after M 1 x V 1 = M 2 x V 2 M is concentration and V is volume. Stock solutions are pre-made to known M

16. Practice 2.0 L of a 0.88 M solution are diluted to 3.8 L. What is the new molarity? 0.46 M

17. Making solutions How many grams of CaCl 2 are needed to make 625 mL of a 2.0 M solution? 139 g

18. Electrolytes Substances that conduct electricity when melted or dissolved in water. Conducting is charged pieces moving Ionic compounds are electrolytes –Fall apart into ions When dissolved When melted

19. Electrolytes Copyright © 2007 Pearson Benjamin Cummings. All rights reserved. (a) Nonelectrolyte (b) Weak electrolyte (c) Strong electrolyte