Look at the single replacement reaction below. Use the rules to assign oxidation numbers to each element in the reaction. Choose the 4 statements below that are TRUE of the reaction.
a
The oxidation number of magnesium increases.
b
The oxidation number of copper decreases.
c
The oxidation number of copper increases.
d
The oxidation number of magnesium decreases.
e
Copper undergoes oxidation.
f
Copper undergoes reduction.
g
Magnesium undergoes oxidation.
h
Magnesium undergoes reduction.
To correctly assign the oxidation numbers and determine which of the given statements are true, we first need to look at the single replacement reaction. However, the actual chemical equation is not provided. Assuming a standard oxidation-reduction reaction between magnesium (Mg) and copper(II) ion (Cu^2+), the reaction would look like this:
Mg(s) + Cu^2+ → Mg^2+ + Cu(s)
Now, let's assign oxidation numbers based on standard rules:
- For elemental magnesium (Mg), the oxidation number is 0.
- For elemental copper (Cu), the oxidation number is also 0.
- For the copper ion (Cu^2+), the oxidation number is +2.
- For the magnesium ion (Mg^2+), the oxidation number is +2.
Now we can determine what has happened during the reaction:
a. The oxidation number of magnesium increases.
True. Magnesium goes from 0 to +2, so it is oxidized.
b. The oxidation number of copper decreases.
True. Copper goes from +2 in the Cu^2+ ion to 0 in elemental copper, so it is reduced.
c. The oxidation number of copper increases.
False. As previously stated, copper is reduced, not oxidized.
d. The oxidation number of magnesium decreases.
False. Magnesium is oxidized, so its oxidation number increases.
e. Copper undergoes oxidation.
False. We established that copper is reduced in this reaction as its oxidation number decreases.
f. Copper undergoes reduction.
True. Copper ions gain electrons and go from +2 to 0.
g. Magnesium undergoes oxidation.
True. Magnesium loses electrons and goes from 0 to +2.
h. Magnesium undergoes reduction.
False. Magnesium is oxidized, not reduced.
The four true statements of the reaction are:
a. The oxidation number of magnesium increases.
b. The oxidation number of copper decreases.
f. Copper undergoes reduction.
g. Magnesium undergoes oxidation.