Question

select the correct answer.
which element or compound has lost electrons in this oxidation-reduction reaction?
4li + 2coo → 2co + 2li₂o
a. coo
b. li₂o
c. li
d. co
e. o

Explanation:

To determine which species lost electrons (oxidized), we analyze oxidation states:

• In \( \text{Li} \) (elemental form), oxidation state is \( 0 \). In \( \text{Li}_2\text{O} \), Li has \( +1 \) (since O is \( -2 \), \( 2(\text{Li}) + (-2) = 0 \Rightarrow \text{Li} = +1 \)). Li's oxidation state increased from \( 0 \) to \( +1 \), meaning it lost electrons (oxidation).
• For \( \text{CoO} \): Co is \( +2 \) (O is \( -2 \), \( \text{Co} + (-2) = 0 \Rightarrow \text{Co} = +2 \)). In \( \text{Co} \) (elemental), oxidation state is \( 0 \): Co was reduced (gained electrons).
• \( \text{Li}_2\text{O} \) is a product, not the species losing electrons.
• \( \text{Co} \) is reduced (gained electrons).
• O in \( \text{CoO} \) and \( \text{Li}_2\text{O} \) has \( -2 \), no change.

So Li lost electrons.

Answer:

C. Li