10:20 Exam II Key; FALL 2009 Dr. Williamson

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

PINK 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) N2   +   3H2  -->   2NH3
limiting = N2
g of NH3 = 1.2 g (2 sig figs)
% Y = 79%

BLUE EXAM

#15 (8 pts)
(a) H2SO4(aq)   +   Mg(OH)2(s)  -->   MgSO4(aq)  +  2H2O(l)
net ionic = 2H+(aq)   +   Mg(OH)2(s)  -->   Mg2+(aq) +  2H2O(l)
(b) 3Na2S(aq)   +   Fe2(SO4)3 (aq)  -->   3Na2SO4(aq)  +  Fe2S3(s)
net ionic = 2Fe3+ (aq)  + 3S2-(aq)   -->   Fe2S3(s) 
(c)  no reaction		 #16 (8pts) C2H4   +   3O2  -->   2CO2 +  2H2O
limiting = O2
g of CO2 = 2.8 g (2 sig figs)
% Y = 71%

YELLOW 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 = 168g (3 sig figs)
% Y = 75.0%