# How many grams of water will be needed to produce 1.5 moles of acetylene gas?

${\left\{C \equiv C\right\}}^{2 -} C {a}^{2 +} + {H}_{2} O \left(l\right) \rightarrow H - C \equiv C - H \left(g\right) \uparrow + C a {\left(O H\right)}_{2} \left(a q\right)$
Such a reaction was the basis of an early miners' lamp. If you need $1.5 \cdot m o l$ acetylene you need $1.5 \cdot m o l$ water, i.e. a mass of $27$ $g$.