Chemistry HW question

Question

A given amount of electric charge deposits 2.159 g of silver from an Ag+ solution. What mass of copper from a Cu^2+ solution will be deposited by the same quantity of electric charge?

Atomic Molar Mass: Ag 107.9 g mol ^-1

Cu 63.5 g mol ^-1

(A) 0.635 g

(B) 1.97 g

(C) 2.54 g

(D) 127 g

Answer 1

Figure out moles of electrons transferred by the given charge that deposited 2.159 g Ag.

Ag⁺ + 1e- ==> Ag(s)

2.159 g Ag x 1 mol / 107.9 g = 0.0200 moles Ag = 0.0200 moles of electrons

Apply this to the deposition of Cu from Cu²⁺

Cu²⁺ + 2e- ==> Cu(s)

0.0200 mols e- x 1 mol Cu²⁺ / 2 mol e- = 0.0100 mols Cu(s)

0.0100 mols Cu x 63.5 g / mol = 0.635 g Cu = ANSWER A