Chapter 6, Problem 60QP

The reaction of lithium metal and water to form lithium hydroxide and hydrogen gas is represented by the following balanced equation:

$\text{2Li}(s)+{\text{2H}}_{\text{2}}\text{O}(l)\to \text{2LiOH}(aq)+{\text{H}}_{\text{2}}(g)$

When Li is mixed with excess water, 0.30 mol ${\text{H}}_{\text{2}}$ gas is isolated in the laboratory. If this reaction occurs to give an 85% yield of ${\text{H}}_{\text{2}}\text{,}$ how many moles of Li reacted?