[mrorganiclover]

Okay, I think I may understand now.

To calculate the theoretical yield from the above information -

CuO is the limiting reagent which has a 1:1 ratio with the product.

Therefore; 1 mol CuO : 1 mol oxalate

0.01006 mol CuO : 0.01006 mol oxalate

0.01006 mol * 389.84 g mol^-1 = 3.9218g