How to Calculate the Amount of Sulfur Needed to Obtain a Specific Mass of CS2?

Question:

If the percentage yield of a reaction is consistently 87%, how many grams of sulfur would be needed to obtain 80.0 g of CS2?

Choose the correct option:

a. 155 g
b. 117 g
c. 54.6 g
d. 234 g

Answer:

Final answer: To obtain 80 g of CS2, approximately 117 g of sulfur would be needed.

To find the amount of sulfur needed to obtain 80 g of CS2, we can use stoichiometry and the percentage yield of the reaction. The balanced equation for the reaction is:

CH4(g) + 4S(g) → CS2(g) + 2H2S(g)

Given that the percentage yield is 87%, the actual yield of CS2 will be 87% of the theoretical yield. First, calculate the molar mass of CS2, which is 76.143 g/mol.

Using the molar mass of CS2, we can find the number of moles of CS2 produced from 80 g:

80 g CS2 x (1 mol CS2/76.143 g CS2) = 1.050 mol CS2

Since 4 moles of sulfur react to produce 1 mole of CS2, the amount of sulfur needed can be calculated:

1.050 mol CS2 x (4 mol S/1 mol CS2) x (32.07 g S/1 mol S) = 116.76 g S

Therefore, approximately 117 grams of sulfur would be needed to obtain 80 grams of CS2.