Question 1

Which of the following best describes oxidation in terms of electrons and oxidation number?

Accepted Answer

Loss of electrons and increase in oxidation number

Question 2

What is the oxidation number of chromium in $$\mathrm{Cr_2O_7$$^{2-}$$}$$?

Accepted Answer

$$+6$$

Question 3

In the reaction $$\mathrm{H_2$(g) + \frac{1}{2} O_2$(g) \rightarrow H_2O(l)}$$, which element is oxidized and which is reduced?

Accepted Answer

Hydrogen is oxidized, oxygen is reduced

Question 4

Assign the oxidation numbers for each element in $$\mathrm{Pb(NO_3$)_2}.$$

Accepted Answer

Pb: $$+2$$, N: $$+5$$, O: $$-2$$

Question 5

Which of the following is the correct oxidation number for hydrogen in $$\mathrm{$$CaH_2$$}$$?

Accepted Answer

$$-1$$

Question 6

In the reaction $$\mathrm{$$TiO_2$$(s) + C(s) + 2Cl_2(g) \rightarrow $$TiCl_4$$(l) + CO_2$(g)}$$, which species acts as the oxidizing agent?

Accepted Answer

$$\mathrm{Cl_2$(g)}$$

Question 7

What is the sum of the oxidation numbers in the polyatomic ion $$\mathrm{SO_4$^{2-}}$$?

Accepted Answer

$$-2$$

Question 8

Which of the following statements about oxidation numbers is correct?

Accepted Answer

The oxidation number of a pure element is zero

Question 9

In the balanced redox reaction $$\mathrm{2Cr(s) + 3Ni$$^{2+}$$(aq) \rightarrow 2Cr$$^{3+}$$(aq) + 3Ni(s)}$$, what is the coefficient on chromium?

Accepted Answer

2

Question 10

When balancing the redox reaction $$\mathrm{Fe$$^{2+}$$(aq) + $$MnO_4$$^-(aq) \rightarrow Fe$$^{3+}$$(aq) + Mn$$^{2+}$$(aq)} in $$acidic solution, what is the coefficient on $$\mathrm{Fe$$^{2+}$$}$$?

Accepted Answer

5

Question 11

Which of the following is the correct order of steps for balancing a redox reaction in acidic solution?

Accepted Answer

Assign oxidation numbers, write half-reactions, balance atoms, balance charge with electrons, add $$\mathrm{H_2O}$$ and $$\mathrm{H^+}$$, combine half-reactions

Question 12

In the compound $$\mathrm{K_2O_2} ($$potassium peroxide), what is the oxidation number of oxygen?

Accepted Answer

$$-1$$

Question 13

Which of the following best describes the change in oxidation number for the element being reduced in a redox reaction?

Accepted Answer

The oxidation number decreases

Question 14

In the reaction $$\mathrm{CH_3CH_2OH \rightarrow CH_3CHO}$$, which element is oxidized and what is the change in its oxidation number?

Accepted Answer

Carbon is oxidized; its oxidation number increases from $$-1 to$$ $$0$$

Question 15

Which of the following is a correct rule for assigning oxidation numbers?

Accepted Answer

The oxidation number of fluorine is always $$-1 in $$its compounds

Question 16

In a basic solution, which additional step must be taken when balancing redox reactions compared to acidic solution?

Accepted Answer

Add $$\mathrm{OH^-} to $$both sides to neutralize $$\mathrm{H^+}$$

Question 17

Which of the following is the correct oxidation number for nitrogen in $$\mathrm{NO_3$^-}$$?

Accepted Answer

$$+5$$

Question 18

A fuel cell uses the reaction $$\mathrm{H_2$(g) + \frac{1}{2} O_2$(g) \rightarrow H_2O(l)}. $$Which species is the reducing agent?

Accepted Answer

$$\mathrm{H_2$}$$

Question 19

In the reaction $$\mathrm{Mn$$^{2+}$$(aq) + H_2O_2(aq) \rightarrow $$MnO_2$$(s) + H_2O(l)} in $$basic solution, which element is reduced?

Accepted Answer

Manganese

Electrochemistry: Oxidation-Reduction Reactions and Balancing Redox Equations

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