Chapter 3, Problem 54A

Interpretation Introduction

Interpretation:

The mass of copper sulfide formed in the given reaction needs to be determined.

Concept introduction:

According to law of conservation of mass, total mass of reactant and product in a chemical reaction remains the same before and after the completion of the reaction.

Answer to Problem 54A

159 g.

Explanation of Solution

The mass of copper is 127 g and that of sulfur is 41 g. The mass of sulfur remains after the reaction (unreacted) is 9 g.

The reactants are copper and sulfur and product is copper (I) sulfide. According to law of conservation of mass, total mass of reactant is equal to the total mass of product. Also, there is sulfur remaining after the reaction thus, the amount of sulfur remaining will be added to the product side.

$m_{Cu}+m_S=m_{C{u}_{2}S}+m_{\text{S, remaining}}$

Putting the values,

$\begin{array}{l}127+41=m_{C{u}_{2}S}+9\\ m_{C{u}_{2}S}=127+41-9=159\text{ g}\end{array}$

Conclusion

Therefore, the mass of copper (I) sulfide formed is 159 g.