We need to go from grams of CuO to mL of H2SO4.
Atomic weight of CuO = 63.55 g Cu + 16 g O = 79.55 g CuO
(.80 g CuO) * (1 mol CuO / 79.55 g CuO) = .0100566 mol CuO (g
CuO cancel)
Since the moles of CuO is a 1:1 ratio to H2SO4 (see balanced
equation) we know that: mol CuO = mol H2SO4 or 0.0100566 mol CuO =
0.0100566 mol H2SO4
3.0 M of H2SO4 means that there is 3 mol / 1 L. So we can divide
this by the moles to get L then mL of H2SO4
(0.0100566 mol H2SO4) * (1 L H2SO4 / 3 mol H2SO4) * (1000 mL
H2SO4 / 1 L H2SO4) = 3.4 mL H2SO4 (mol H2SO4 and L H2SO4
cancel)
So 3.4 ml of H2SO4 is needed to react with 0.80 g of CuO.