If a student calculated 0.02789 moles of copper (II) cations (Cu2 + ions) in the sample, how many moles of copper metal (Cu0) could be obtain from the sample at the end of the experiment?

0.02789 moles of copper metal, Cu⁰, atoms.

Explanation:

The formation of copper metal (Cu⁰) from copper (II) cations, Cu²⁺ ions, may be represented by the following reduction half-reaction:

Cu²⁺ + 2e⁻ → Cu⁰

That means that one Cu²⁺ ion (or one mole of Cu²⁺ ions) gains 2 electrons, reducing itself, to form one Cu⁰ metal atom (or one mol of Cu⁰ metal atoms).

Thus, the stoichiometry is 1 : 1, and you conclude that 0.02789 moles of copper (II) cations, Cu²⁺, permit, theoretically, obtain the same number of moles of Cu⁰ metal atoms.