Question

Copper(l) sulfide can react with oxygen to produce copper metal by the reaction cu2s + o2 => 2cu + so2. if 5.00 g of cu2s is used, then what is the theoretical yield of cu?

Answer 1

To answer this problem, we write first the stoichiometric equation. Thus we have,

Cu2S + O2 => 2Cu + SO2

Next, we check if the equation is balanced or not.

(left)     (right)
2 Cu  = 2 Cu
1 S  =  1 S
2 O = 2 O

So the stoichiometric equation is balanced, let's proceed in solving the theoretical yield of Cu given 5 g of Cu2S.

First, we solve for Cu2S in moles,
5 g Cu2S x 1 mol Cu2S   = 0.0314 mol Cu2S
                159.16 g Cu2s

Secondly, convert moles of Cu2S to moles Cu. Note for every mole of Cu2S we get 2 moles of Cu. Thus,

0.0314 mo Cu2S x    2 mol Cu      = 0.0628 mole Cu
                                1 mol Cu2S

Lastly, we convert mole Cu to g Cu via multiplying by Cu's MW.

0.0628 mole Cu x 63.546 g Cu   = 3.99 g Cu or 4 g Cu
                                1 mole Cu

ANSWER: 4 g Cu

Answer 2

The theoretical yield of Cu in the reaction ${\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}+{{\text{O}}_2}\to2{\text{Cu}}+{\text{S}}{{\text{O}}_2}$ is $\boxed{{\text{4 g}}}$  

Further Explanation:

Stoichiometry of a reaction is used to determine the amount of species present in the reaction by the relationship between the reactants and products. It can be used to determine the moles of a chemical species when the moles of other chemical species present in the reaction is given.

Consider the general reaction,

 ${\text{A}}+2{\text{B}}\to3{\text{C}}$

Here,

A and B are reactants.

C is the product.

One mole of A reacts with two moles of B to produce three moles of C. The stoichiometric ratio between A and B is 1:2, the stoichiometric ratio between A and C is 1:3 and the stoichiometric ratio between B and C is 2:3.

The given reaction is,

 ${\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}+{{\text{O}}_2}\to2{\text{Cu}}+{\text{S}}{{\text{O}}_2}$

• On reactant side,

Number of copper atoms is 2.

Number of sulfur atom is 1.

Number of oxygen atoms is 2.

• On the product side,

Number of copper atoms is 2.

Number of sulfur atom is 1.

Number of oxygen atoms is 2.

The number of atoms of all the species in both the reactant and the product side is the same. So above reaction is balanced. The stoichiometry of the balanced reaction indicates that 1 mole of ${\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}$ reacts with 1 mole of ${{\text{O}}_2}$ to form 2 moles of Cu and 1 mole of ${\text{S}}{{\text{O}}_2}$ .

The formula to calculate the number of moles of ${\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}$ is as follows:

${\text{Moles of C}}{{\text{u}}_{\text{2}}}{\text{S}}=\frac{{{\text{Given mass of C}}{{\text{u}}_{\text{2}}}{\text{S}}}}{{{\text{Molar mass of C}}{{\text{u}}_{\text{2}}}{\text{S}}}}$                                               ......(1)

The given mass of ${\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}$ is 5 g.

The molar mass of ${\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}$ is 159.16 g/mol.

Substitute these values in equation (1)

$\begin{aligned}{\text{Moles of C}}{{\text{u}}_{\text{2}}}{\text{S}}{\mathbf{&=}}\left( {5\;{\text{g}}}\right)\left({\frac{{{\text{1}}\;{\text{mol}}}}{{{\text{159}}{\text{.16}}\;{\text{g}}}}}\right)\\&=0.0314\;{\text{mol}}\\\end{aligned}$

According to the stoichiometry, 1 mole of ${\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}$ react with 1 mole of ${{\text{O}}_2}$ to form 2 moles of Cu.

So the number of moles of Cu formed by 0.0314 moles of ${\text{C}}{{\text{u}}_{\text{2}}}{\text{S}}$ is calculated as follows:

$\begin{aligned}{\text{Moles of Cu}}{\mathbf{&=}}\left(2\right)\times\left( {0.0314}\right)\\&=0.0628\;{\text{mol}}\\\end{aligned}$

The formula to calculate the mass of Cu is as follows:

${\mathbf{Mass\:of\:Cu=}}\left({{\mathbf{Moles\:of\:Cu}}}\right){\mathbf{\times}}\left( {{\mathbf{Molar\:mass\:of \:Cu}}}\right)$  ......(2)

The moles of Cu are 0.0628 mol.

The molar mass of Cu is 63.546 g/mol.

Substitute these values in equation (2)

$\begin{aligned}{\text{Mass of Cu}}&=( {0.0628\text{ mol})\times\left(\dfrac{63.546\text{ g}}{1\text{ mol}}\right)\\&={\text{3}}{\text{.99 g}}\\&\approx {\text{4 g}}\\\end{aligned}$

So the theoretical yield of Cu during the reaction is 4 g.

Learn more:

1. Balanced chemical equation: https://brainly.com/question/1405182

2. What coefficients are required to balance equation: https://brainly.com/question/1971314

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Mole concept

Keywords: stoichiometry, Cu2S, Cu, O2, Cu2S, moles, A, B, C, theoretical yield, 4g, molar mass, reactants, products, 0.0314 moles, 0.0628 moles, copper, sulfur, oxygen.