Question

Directions: Answer each of the following questions. Be sure to use complete sentences where appropriate. For full credit be sure to show all of your work. Where appropriate answers should be boxed for clarity, written to the correct number of significant figures, and, include the proper units. 1. Which of the following is a chemical reaction (4 points)? a. Solid copper deposits on a piece of aluminum foil when the foil is placed in a blue copper(II) nitrate solution. The blue color of the solution fades. b. Liquid ethyl alcohol turns into a solid when placed in a low- temperature freezer. A white precipitate forms when solutions of barium nitrate and sodium sulfate are mixed. A mixture of sugar and water bubbles when yeasts are added. After several days, the sugar is gone and ethyl alcohol is found in the water. 2. Consider the following unbalanced chemical equation (5 points): Al(s) + Cl2 → AICI3 (s) a. Classify the reaction by the type of chemistry: combination, combustion, decomposition, single replacement, or double replacement reaction. Combination reaction b. A chemistry student tried to balance the equation by changing the subscript 2 on Cl to a 3. Why this is not correct. What is the correct balanced equation? 3. Consider the following balanced total ionic equation (11 points): 2 K+ (aq) + S2+ (aq) + Pb2+ (aq) + 2 NO3(aq) → PbS (s) + 2 K+ (aq) + 2 NO; (aa) a. Identify the spectator ion(s). b. Classify the reaction by the type of chemistry. c. Write the balanced conventional equation. d. Write the net ionic equation.

Answer 1

® Chemical reactions are (aj Combination reaction ibo chlorine exists as clz and not as Cl3 32A1(s) + 3Cl2(g) - > 2AlCl3 (s) (a) speetabov pous = k* and Noz cb Double replacement veachion n (6) K25 (aq) + Pb(NO3)2 (aq) Roe Pbs(s) + 2 KNO3 log) d) Pb2+ (aq) + 8? Cag) → Pbs(s) cs Scanned with A NSWERS