Question

Question #e15e7

Answer 1

You must use `"69.68 g of Na"_2"S"` to produce `"50.00 g of TiS"_2`.

Explanation:

There are four steps to answering this type of stoichiometry problem.

1. Write the balanced equation for the reaction.
2. Use the molar mass of `"TiS"_2` to convert grams of `"TiS"_2` to moles of `"TiS"_2`.
3. Use the molar ratio from the balanced equation to convert moles of `"TiS"_2` to moles of `"Na"_2"S"`.
4. Use the molar mass of `"Na"_2"S"` to convert grams of `"Na"_2"S"` to moles of `"Na"_2"S"`.

Step 1. Write the balanced equation.

`"2Na"_2"S" + "TiCl"_4 → "4NaCl" + "TiS"_2`

Step 2. Convert grams of `"TiS"_2` to moles of `"TiS"_2`.

The molar mass of `"TiS"_2` is 112.00 g/mol.

`50.00 cancel("g TiSO"_2) × ("1 mol TiSO"_2)/(112.00 cancel("g TiS"_2)) = "0.446 43 mol TiS"_2`

Step 3. Use the molar ratio to calculate the moles of `"Na"_2"S"`.

From the balanced equation, the molar ratio is `"2 mol Na"_2"S":"1 mol TiS"_2`.

`"0.446 43" cancel("mol TiS"_2) × ("2 mol Na"_2"S")/(1 cancel("mol TiS"_2)) = "0.892 86 mol Na"_2"S"`

Step 4. Convert moles of `"Na"_2"S"` to grams of `"Na"_2"S"`.

`"0.892 86" color(red)(cancel(color(black)("mol Na"_2"S"))) × ("78.04 g Na"_2"S")/(1 color(red)(cancel(color(black)("mol Na"_2"S")))) = "69.68 g Na"_2"S"`

You need to use `"69.68 g of Na"_2"S"`.