Question

Ca + 2H2O → Ca(OH)2 + H2.

How many moles of H2O are needed to exactly react with 2. 0 moles of Ca?

Answer 1

The balanced chemical equation shows that 1 mole of Ca reacts with 2 moles of H2O to produce 1 mole of Ca(OH)2 and 1 mole of H2.

Therefore, to react with 2.0 moles of Ca, we need 2.0 moles of Ca x (2 moles H2O / 1 mole Ca) = 4.0 moles of H2O.

So, 4.0 moles of H2O are needed to exactly react with 2.0 moles of Ca.