CHEM121 EXAM 2 QUESTIONS AND EXPECTED ANSWERS

CHEM121 EXAM 2 QUESTIONS
AND EXPECTED ANSWERS

Which of the following represents oxidation?
a. 2H+ + 2e- ->H2
b. F2 + 2e- -> 2F-
c. Na -> Na+ + e-
d. Mg2+ + 2e- -> Mg
e. Ni2+ + 2e- -> Ni
c.
Which element is reduced in the reaction below?
Na2SO4 + 4C -> Na2S + 4CO
S
What is the oxidation number of P in (PO4)3-?
+5
What is the molarity of a solution that results when
21.3g of (NH4)3PO4 is dissolved in water and diluted
to exactly 250.0ml?
0.572 M
Which is not an electrolyte?
a. H20
b. NH4Cl
c. KI
d. CuS
a.
Which of the methods will yield 500 mL of a 0.100M
KMnO4 solution?
a. Add exactly 500mL of water to 7.90g of KMnO4.
b. Add exactly 500mL of water to 159g KMnO4.

, c. Dissolve 7.90g of KMnO4 in water and dilute to
exactly 500mL.
d. Dissolve 15.8g of KMnO4 in water and dilute to
exactly 500mL.
e. Dilute 220mL of 1.00M KMnO4 to exactly 500mL.
c.
A 25.00mL sample of NaOH is titrated with 15.23mL of
0.2250M HCl. What is the concentration of the NaOH
solution?
0.1371 M
Which statement about the reaction below is correct?
K2SO4 + Ba(NO3)2 -> BaSO4 + 2KNO3

a. both BaSO4 and KNO3 will precipitate.
b. no reaction will occur because K2SO4 is insoluble.
c. BaSO4 will precipitate.
d. Neither BaSO4 nor KNO3 will precipitate.
e. KNO3 will precipitate.
c.
What are the spectator ions in the reaction between
nitric acid and sodium hydroxide?
Na+ and NO3-
What is the molarity of a MnO4- solution if 23.5mL of
this solution is required to react completely with
30.0mL of 0.134M Fe2+ solution according to the
equation:
5Fe2+(aq)+MnO4-(aq)+8H+(aq) -> 5Fe3+(aq)+Mn2+(aq)
+4H2O(l)
0.0342 M
Which compound will dissolve in water in large
amounts?