Question

A 2.89 g sample of sulfur reacts with 5.72 g of copper to form a black compound. What is the percentage composition of the compound?

Answer 1

Answer:

The answers in mass percent are = mass of reactant / total mass of sample * 100:

% Cu = 2.89 g / (2.89 g + 5.72 g) * 100 = 33.6

% S = 5.72 g / ( 2.89 g + 5.72 g) * 100 = 66.4

Answer 2

Given: A 2.89 g sample of sulfur reacts with 5.72 g of copper to form a black compound.

To find: We have to find the percentage composition of the compound.

Solution:

A 2.89 g sample of sulfur reacts with 5.72 g of copper to form a black compound and this black compound is copper sulphide having molecular formula $CuS$.

The percentage of composition is a ratio of composition of reactent to total composition multiplied by 100.

Percentage composition of copper is

$\frac{2.89}{2.89 + 5.72} \times 100 = 33.5$

Percentage composition of sulphur is

$\frac{5.72}{8.61} \times 100 = 66.4$

So, percentage composition of Cu is 33.5% and sulphur ia 66.4%.