Unit 17

The oxidation number of oxygen atoms in compounds is usually ________________.

• 0.

• –1.

• –2.

• +1.

The part of a reaction that involves only oxidation or reduction is a(n) _____________.

• redox reaction.

• reduction reaction.

• oxidation-reduction equation.

• half-reaction.

The sum of the oxidation numbers for all atoms in a polyatomic ion is equal to _____________.

• –2.

• 0.

• the charge on that ion.

• the charge of the products.

The sum of the oxidation numbers for all the atoms in a molecule is equal to _____________.

• –2.

• 0.

• the charge on that ion.

• the charge of the products.

If oxidation is taking place, what also must be occurring?

• electroplating

• corrosion

• electrolysis

• reduction

Another name for an oxidation-reduction reaction is _________________.

• oxidizing agent.

• redox reaction.

• reducing agent.

• half-reaction.

The oxidation number of uncombined iodine(I2) is ______________.

• 0.

• –1.

• –2.

• +1.

The element sulfur can exist in all of the following oxidation states except ______________.

• –2.

• +4.

• +5.

• +6.

When Cr3+ changes to Cr0, the chromium ion is said to have been _________________.

• oxidized because it gained 3e–.

• oxidized because it lost 3e–.

• reduced because it gained 3e–.

• reduced because it lost 3e–.

The term oxidation arose early in the history of chemistry, when scientists observed elements combining with oxygen in combustion reactions. For example, S(s) + O2(g) → SO2(g) In this reaction, _________________.

• the oxygen is oxidized and the sulfur is oxidized.

• the oxygen is oxidized and the sulfur is reduced.

• the oxygen is reduced and the sulfur is reduced.

• the oxygen is reduced and the sulfur is oxidized.