Instructions - Answer each of the following questions using the quiz on the clas
ID: 519187 • Letter: I
Question
Instructions - Answer each of the following questions using the quiz on the class site. Answers arc due at 12:00 PM on Thursday, April 27^th. This quiz counts as a standard quiz grade. Questions with choices provided are worth one point each; questions with choices provided are worth two points each. What is the oxidation number of molybdenum in H_3 Mo_2 O_24^3? a) -2 b) +2 c) +3 d) +6 The chemical reaction that occurs in a lead-acid battery is given below. What is reducing agent in this reaction? PbO_2 (s) + Pb(s) + 2HSO^- _4 (aq) + 2H^+ (aq) rightarrow 2PbSO_4 (s) + 2H_2 O(l) a) PbO_2 (s) b) Pb(s) c) HSO_4 (aq) d) H^+ (aq) What is the coefficient in front of copper(I) oxide when the unbalanced redox _2 O^2- _3 + Cu_2 O rightarrow SO^2- _3 + Cu is balanced in basic solution? Enter your answer as a In the electrolysis of water, which gas (H_2 or O_2) will be collected at the cathode?Explanation / Answer
1. d
3 +7(Mo) + 24 (-2) = -3
3-48+ 7 Mo = -3
7 Mo = 42
Mo = 6
Oxidation number of Molybdenum = +6
2) b
At anode :
Pb(s) + SO42- ---------> PbSO4 (s) + 2e-
At cathode :
2e- + PbO2 (s) + 4 H+(aq) + SO42-(aq) ---------> PbSO4(s ) + 2H2O (l)
Overall equation : Pb + SO42-(aq) + 4 H+(aq) +PbO2 + SO42- ------->PbSO4 (s) + PbSO4(s ) + 2H2O (l)
Pb + PbO2+ 4 H+(aq) + 2SO42-(aq) ---------> 2 PbSO4(s ) + 2H2O (l)
4 H+(aq) + 2SO42-(aq) can be written as 2HSO4- +2H+
Pb (s)+ PbO2(s)+ 2HSO4-(aq) +2H+ ------------> 2 PbSO4(s ) + 2H2O (l)
The loss of electrons is reducing agent.