I do not understand stoichiometry

Question

In the balanced chemical equation below, how many moles of copper(II) carbonate are made from the reaction of 42 grams of copper(II) sulfate and excess silver carbonate?

 

CuSO₄ + Ag₂CO₃ --> Ag₂SO₄ + CuCO₃

Answer 1

Stoichiometry simply relates the moles of each compound in the balanced equation. So in the current problem, the stoichiometry tells us that all of the compounds are in a 1 : 1 mol ratio. So, 1 mol CuSO₄ reacts with 1 mol Ag₂CO₃ to produce 1 mol Ag₂SO₄ and 1 mol of CuCO₃.

We are given GRAMS (not moles) of CuSO₄, so we must convert this to moles (stoichiometry is in moles not grams). 42 g CuSO₄ x 1 mol CuSO₄ / 160 g = 0.2625 moles CuSO₄

Now we can relate (on a mole basis) CuSO₄ to CuCO₃ since they are in a 1 : 1 mol ratio.

Moles of CuCO₃ produced: 0.2625 mol CuSO₄ x 1 mol CuCO₃ / 1 mol CuSO₄ = 0.2625 mol CuCO₃

Rounding to 2 sig. figs. we have 0.26 moles CuCO₃