12:40 Exam II Key; FALL 2009 Dr. Williamson

White, Exam II, v1 Green, Exam II, v2 QUESTION Lavender, Exam II, v3
6 pts each unless noted  6 pts each unless noted   6 pts each unless noted
E (B,C=3 pts) E (B,C=3 pts) 1 D
D E (D=3 pts) 2 B
D (A=3 pts) C (A=3 pts) 3 A (B,C=3 pts)
D (E=3 pts) E 4 B (C=3 pts)
E B (A=3 pts) 5 C (D=3 pts)
E (C=3 pts) D (A,B=3 pts) 6 E (B,C=3 pts)
B C 7 C
C B 8 B
D E 9 B
B B 10 A
B E 11 D (E=3 pts)
D (B,E=3 pts) D 12 D
B (D=3 pts) C 13 C (A=3 pts)
D E (C=3 pts) 14 D

(14 x 6) = 84 pts on multiple choice
16 more points on short answer-See the bulletin board outside room 123b for the solutions.

WHITE EXAM

#15 (8 pts)
(a)  no reaction
(b) H2SO4(aq)   +   Mg(OH)2(s)  -->   MgSO4(aq)  +  2H2O(l)
net ionic = 2H+(aq)   +   Mg(OH)2(s)  -->   Mg2+(aq) +  2H2O(l)
(c) 3Na2S(aq)   +   Fe2(SO4)3 (aq)  -->   3Na2SO4(aq)  +  Fe2S3(s)
net ionic = 2Fe3+ (aq)  + 3S2-(aq)   -->   Fe2S3(s)  		#16 (8pts) C3H8   +   5O2  -->   3CO2 +  4H2O
limiting = C3H8
g of CO2 = 48.0 g (3 sig figs)
% Y = 83.3%

GREEN EXAM

#15 (8 pts)
(a) 3Na2S(aq)   +   Fe2(SO4)3 (aq)  -->   3Na2SO4(aq)  +  Fe2S3(s)
net ionic = 2Fe3+ (aq)  + 3S2-(aq)   -->   Fe2S3(s)
(b) HNO2(aq)   +   KOH (aq)  -->   KNO2(aq)  +  H2O(l)
net ionic = HNO2(aq)  +OH-(aq)   -->   NO2-(aq)  +  H2O(l)
(c)  no reaction		 #16 (8pts) C   +   2Cl2  -->   CCl4
limiting = Cl2
g of CCl4 = 34g (2 sig figs)
% Y = 76%

LAVENDER EXAM

#15 (8 pts)
(a) 2Na3PO4(aq)   +   3Mg(NO3)2 (aq)  -->   6NaNO3(aq)  +  Mg3(PO4)2(s)
net ionic = 2PO43- (aq)  + 3Mg2+(aq)   -->   Mg3(PO4)2(s)
(b) no reaction
(c)  HNO2(aq)   +   NaOH(aq)  -->   NaNO2(aq)  +  H2O(l)
net ionic = HNO2(aq)   +   OH-(aq)  -->   NO2-(aq)  +  H2O(l) 		#16 (8pts) C2H4   +   3O2  -->   2CO2 +  2H2O
limiting = O2
g of CO2 = 2.8 g (2 sig figs)
% Y = 71%