Question

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

Answer 1

`318` grams `Cu_2S`

Explanation:

1. First know what element/compound involved in the problem. In this case, it's `S` and `Cu_2S`;
2. Once known, find the atomic mass and the molar mass, respectively for stoichiometric calculation later;
   `S`= 32 gram/mol
   `Cu_2S`=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 `grams` of `Cu_2S`;
   `64 cancel(g S)`x`(1 cancel(mol S))/(32 cancel(g S))`x`(1 cancel(mol Cu_2S))/(1 cancel(mol S))`x`(159 g Cu_2S)/(1 cancel(mol Cu_2S))`
4. The answer is `318` `grams` `Cu_2S`