58 . C
Ionic solutions will conduct electricity. The NaCl will dissociate to become Na+ and Cl–. The
same occurs when you melt the NaCl. Solid NaCl and pure water are not ionic solutions.59 . B
NaCl is an ionic compound with ionic bonds because it is formed when Na donates an electron
to Cl. The bond is formed by the electrostatic interaction between the positive and negative
ions.
60 . B
Glucose molecules carry no electrical charge, so there are no electrical charges in the solution
to provide conduction.
61 . C
This Roman-numeral question asks which of the given statements describe a galvanic cell
(remember more than one of the answers may be correct). Galvanic cells are capable of
spontaneous reactions. In all electrochemical cells, oxidation occurs at the anode and
reduction occurs at the cathode. In addition, the anode in a galvanic cell is negative, meaning
that it is a source of electrons. Since a species loses electrons when it is oxidized, this should
make sense. There is a trick to remembering these facts. In a galvanic cell, oxidation occurs at
the anode, which is negative. Alphabetically, anode comes before cathode, oxidation before
reduction, and negative before positive. However, this little trick only works for galvanic cells.
62 . E
34 g of NH 3 at 17 g/mol equals 2 mol combusted. Two moles are combusted at 81 kcal/mol.
This equation would be (2 mol)(81 kcal/mol) = 162 kcal.
63 . D
The s subshells contain only 2 electrons. Their principal, azimuthal, and magnetic quantum
numbers are identical, but due to Pauli’s exclusion principle their spin quantum numbers
must be +1/2 and –1/2. Therefore, they have opposite spins.
64 . C
A buffer is a solution made from a mixture of a weak acid and a salt containing its anion.
Buffers resist pH change due to the addition of acid or base. Thus, to make a buffer solution
with a weak monoprotic acid, the addition of the corresponding salt is required. This salt must