. In the production of copper from ore containing copper(II) sulfide, the ore is first roasted to change it to the oxide according to the following equation: 2CuS 3O2 £ 2CuO 2SO2 a. If 100 g of CuS and 56 g of O2 are available, which reactant is limiting? b. What mass of CuO can be formed from the reaction of 18.7 g of CuS and 12.0 g of O2? 4. A reaction such as

From this we conclude that, [tex]O_2[/tex] is an excess reagent because the given moles are greater than the required moles and [tex]CuS[/tex] is a limiting reagent and it limits the formation of product.

Hence, the limiting reactant is, CuS

Part (b) :

Given,

Mass of [tex]CuS[/tex] = 18.7 g

Mass of [tex]O_2[/tex] = 12.0 g

Molar mass of [tex]CuS[/tex] = 95.6 g/mol

Molar mass of [tex]O_2[/tex] = 32 g/mol

First we have to calculate the moles of [tex]CuS[/tex] and [tex]O_2[/tex].

[tex]\text{Moles of }CuS=\frac{\text{Given mass }CuS}{\text{Molar mass }CuS}[/tex]

[tex]\text{Moles of }CuS=\frac{18.7g}{95.6g/mol}=0.196mol[/tex]

and,

[tex]\text{Moles of }O_2=\frac{\text{Given mass }O_2}{\text{Molar mass }O_2}[/tex]

[tex]\text{Moles of }O_2=\frac{12.0g}{32g/mol}=0.375mol[/tex]

Now we have to calculate the limiting and excess reagent.

The balanced chemical equation is:

[tex]2CuS+3O_2\rightarrow 2CuO+2SO_2[/tex]

From the balanced reaction we conclude that

As, 2 mole of [tex]CuS[/tex] react with 3 mole of [tex]O_2[/tex]

So, 0.196 moles of [tex]CuS[/tex] react with [tex]\frac{3}{2}\times 0.196=0.294[/tex] moles of [tex]O_2[/tex]

From this we conclude that, [tex]O_2[/tex] is an excess reagent because the given moles are greater than the required moles and [tex]CuS[/tex] is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of [tex]CuO[/tex]

From the reaction, we conclude that

As, 2 mole of [tex]CuS[/tex] react to give 2 mole of [tex]CuO[/tex]

So, 0.196 mole of [tex]CuS[/tex] react to give 0.196 mole of [tex]CuO[/tex]

Now we have to calculate the mass of [tex]CuO[/tex]

[tex]\text{ Mass of }CuO=\text{ Moles of }CuO\times \text{ Molar mass of }CuO[/tex]

Molar mass of [tex]CuO[/tex] = 79.5 g/mole

[tex]\text{ Mass of }CuO=(0.196moles)\times (79.5g/mole)=15.6g[/tex]

Therefore, the mass of [tex]CuO[/tex] produced is, 15.6 grams.