CHEM 116 CORE EXAM QUESTIONS WITH ANSWERS
2025/2026
___ electrons appear in the following half-reaction when it is balanced S4O6 -> 2SO3 -
2
The balanced half-reaction in which chlorine gas s reduced to the aqueous chloride ion
is a ____ process. - six-electron
The balanced half-reaction in which dichromate ion is reduced to chromium metal is a
____ process. - twelve-electron
The balanced half-reaction in which dichromate ion is reduced to chromium (III) ion is a
+____ process. - six-electron
The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a ___ process.
- two-electron
The electrode at which oxidation occurs is called the - anode
The half-reaction occurng at the anode in the alanced reaction shown below is ___.
3MnO4+24H+5Fe -> 3Mn+5Fe+12H2O - Fe(s)->Fe 3+(aq) + 3e-
In a voltaic cell, electrons flow from the ___ to the ___. - anode, cathode
The reduction half-reaction occurring in the standard hydrogen electrode is ___. -
2H+(aq, 1M) + 2e- -> H2 (g, 1atm)
1V = ___? - 1 J/C
The more ___ the value of Ered, the greater the driving force for reduction. - positive
The relationship between the change in Gibbs free energy and the emf of an
electrochemical cell is given by ___. - DeltaG = -nFE
The lead-containing reactant(s) consumed during recharging of a lead-acid batter is/are
___. - PbSO4 (s) only
Galvanized iron is iron coated with ___. - iron oxide
Corrosion of iron is retarded by ___. - both presence of salts and low pH conditions
What is the oxidation number of bromine in the BrO3- ion? - +5
What is the oxidation number of nitrogen in HNO3? - +5
, What is the oxidation number of sulfur in HSO4- ion? - +6
Which element is oxidized in Fe(CO)5+2HI -> Fe(CO)4I2 +CO +H2 - Fe
Which element is reduced in Fe(CO)5+2HI -> Fe(CO)4I2 +CO +H2 - H
Which element is oxidized in Fe+2 +H+Cr2O7 -> Fe+3 +Cr+H2O - Fe
Which element is reduced in Fe+H+Cr2O7 -> Fe+Cr+H2O - Cr
Which element is oxidized in I- + MnO4- +H+ -> I2+ MnO2+H2O - I
Which element is reduced in I- + MnO4- +H+ -> I2+ MnO2+H2O - Mn
Which substance is the reducing agent in the following reaction? Fe2S3 + 12HNO3 ->
2Fe(NO3)3 +3S+6NO2+6H2O - Fe2S3
What is the coefficient of the permanganate ion when the following equation is
balanced? MnO4- + Br- -> Mn+2 + Br2 (acidic solution) - 2
Which one of the following correctly indicates the relationshop between the entropy of a
system and the number of different arrangement, W, in the system? - S = k lnW
`If DeltaG for a reacton s less than zero, then - K > 1
T/F The melting of a substance at its melting point is an isothermal process. - True
The vaporization of a substance at its boiling point is an isothermal process. - True
The quantity of energy gained by a system equals the quantity of energy gained by its
surroundings. - False
The entropy of a pure crystalline substance at 0 C is zero. - False
The more negative DeltaG is for a given reaction, the larger the value of the
corresponding equilibrium constant, K. - True
The gain of electrons by an element I called - Reduction
____ is reduced in Cr2O7+6S2O3+14H -> 2Cr +3S4O6+7H2O - Cr 6+
____ is the oxisizing agent in Cr2O7+6S2O3+14H -> 2Cr +3S4O6+7H2O - Cr2O7 2-
Which substance is serving as the reducing agent in the following 14H+Cr2O7+3Ni ->
3Ni+2Cr+7H2O - Ni
2025/2026
___ electrons appear in the following half-reaction when it is balanced S4O6 -> 2SO3 -
2
The balanced half-reaction in which chlorine gas s reduced to the aqueous chloride ion
is a ____ process. - six-electron
The balanced half-reaction in which dichromate ion is reduced to chromium metal is a
____ process. - twelve-electron
The balanced half-reaction in which dichromate ion is reduced to chromium (III) ion is a
+____ process. - six-electron
The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a ___ process.
- two-electron
The electrode at which oxidation occurs is called the - anode
The half-reaction occurng at the anode in the alanced reaction shown below is ___.
3MnO4+24H+5Fe -> 3Mn+5Fe+12H2O - Fe(s)->Fe 3+(aq) + 3e-
In a voltaic cell, electrons flow from the ___ to the ___. - anode, cathode
The reduction half-reaction occurring in the standard hydrogen electrode is ___. -
2H+(aq, 1M) + 2e- -> H2 (g, 1atm)
1V = ___? - 1 J/C
The more ___ the value of Ered, the greater the driving force for reduction. - positive
The relationship between the change in Gibbs free energy and the emf of an
electrochemical cell is given by ___. - DeltaG = -nFE
The lead-containing reactant(s) consumed during recharging of a lead-acid batter is/are
___. - PbSO4 (s) only
Galvanized iron is iron coated with ___. - iron oxide
Corrosion of iron is retarded by ___. - both presence of salts and low pH conditions
What is the oxidation number of bromine in the BrO3- ion? - +5
What is the oxidation number of nitrogen in HNO3? - +5
, What is the oxidation number of sulfur in HSO4- ion? - +6
Which element is oxidized in Fe(CO)5+2HI -> Fe(CO)4I2 +CO +H2 - Fe
Which element is reduced in Fe(CO)5+2HI -> Fe(CO)4I2 +CO +H2 - H
Which element is oxidized in Fe+2 +H+Cr2O7 -> Fe+3 +Cr+H2O - Fe
Which element is reduced in Fe+H+Cr2O7 -> Fe+Cr+H2O - Cr
Which element is oxidized in I- + MnO4- +H+ -> I2+ MnO2+H2O - I
Which element is reduced in I- + MnO4- +H+ -> I2+ MnO2+H2O - Mn
Which substance is the reducing agent in the following reaction? Fe2S3 + 12HNO3 ->
2Fe(NO3)3 +3S+6NO2+6H2O - Fe2S3
What is the coefficient of the permanganate ion when the following equation is
balanced? MnO4- + Br- -> Mn+2 + Br2 (acidic solution) - 2
Which one of the following correctly indicates the relationshop between the entropy of a
system and the number of different arrangement, W, in the system? - S = k lnW
`If DeltaG for a reacton s less than zero, then - K > 1
T/F The melting of a substance at its melting point is an isothermal process. - True
The vaporization of a substance at its boiling point is an isothermal process. - True
The quantity of energy gained by a system equals the quantity of energy gained by its
surroundings. - False
The entropy of a pure crystalline substance at 0 C is zero. - False
The more negative DeltaG is for a given reaction, the larger the value of the
corresponding equilibrium constant, K. - True
The gain of electrons by an element I called - Reduction
____ is reduced in Cr2O7+6S2O3+14H -> 2Cr +3S4O6+7H2O - Cr 6+
____ is the oxisizing agent in Cr2O7+6S2O3+14H -> 2Cr +3S4O6+7H2O - Cr2O7 2-
Which substance is serving as the reducing agent in the following 14H+Cr2O7+3Ni ->
3Ni+2Cr+7H2O - Ni
