# What is the mass of Cu_2S formed if 64 g of S are used in the reaction 2Cu + S -> Cu_2S?

Mar 21, 2016

$318$ grams $C {u}_{2} S$

#### Explanation:

1. First know what element/compound involved in the problem. In this case, it's $S$ and $C {u}_{2} S$;
2. Once known, find the atomic mass and the molar mass, respectively for stoichiometric calculation later;
$S$= 32 gram/mol
$C {u}_{2} S$=159 gram/mol
3. Start the calculation with the mass of $S$ as provided in the problem and all the way to the desired answer using all data you have gathered. Make sure to cancel units out, leaving your desired unit which is mass in $g r a m s$ of $C {u}_{2} S$;
$64 \cancel{g S}$x$\frac{1 \cancel{m o l S}}{32 \cancel{g S}}$x$\frac{1 \cancel{m o l C {u}_{2} S}}{1 \cancel{m o l S}}$x$\frac{159 g C {u}_{2} S}{1 \cancel{m o l C {u}_{2} S}}$
4. The answer is $318$ $g r a m s$ $C {u}_{2} S$