Question

12 gram of commercial zinc is made to react with excess dilute H2SO4. The total volume of hydrogen gas liberated was found to be 4.2 litre at 570mm Hg pressure and 279 K. Determine percentage purity of zinc. (At. mass of Zn= 65)

Answer 1

Answer:

The zinc sample was 74.96% pure.

Explanation:

$Zn+H_2SO_4\rightarrow ZnSO_4+H_2$

Mass of zinc made to react= 12 g

Moles of hydrogen gas evolved on reaction will be calculated by using ideal gas equation:

$PV=nRT$

$0.75 atm\times 4.2 L=n\times 0.0820 atm l/ mol L\times 279 K$

n = 0.1376 mol

According to reaction 1 mol of hydrogen gas was produced form 1 mol of zinc.

Then  0.1376 mol of hydrogen gas will be produce by:$\frac{1}{1}\times 0.1376 =0.1376 mol$ of zinc.

Mass of zinc in 0.1376 mol= 0.1376 mol × 65.38 g/mol=8.9962 g

Percentage purity of zinc=$\frac{8.9962 g}{12 g}\times 100=74.96\%$

The zinc sample was 74.96% pure.

Answer 2

Answer:I got answer

Explanation: