Question

12 g of commercial zinc is made to react with excess dilute H2SO4 .The total volume of hydrogen gas liberated was found to be 4.2 litres at 520 mmHg pressure and 279 K. Determine the percentage purity of the zinc.

Answer 1

Answer:

68%

Explanation:

Balance equation for reaction Zinc with sulphuric acid is given by,

$Zn+H_2SO_4-------> ZnSO_4+H_2$

One mole of Zinc reacts with sulphuric acid to form one mole of hydrogen.

Number of moles of Hydrogen gas formed can found out using PV=nRT.

P=520 mmHg i.e. 0.68 atm (1 atm = 760 mmHg)

V= 4.2 L

R = 0.0821

T = 279 K

Putting value in the equation n=0.125 mol.

So the mass of zinc reacted to form Hydrogen gas is 8.2 g of Zinc.

Purity of the compound is Actual mass/mass taken*100

=>8.2/12*100= 68%

Answer 2

Explanation:

Balance equation for reaction Zinc with sulphuric acid is given by,

Zn+H_2SO_4-------> ZnSO_4+H_2Zn+H

2

SO

4

−−−−−−−>ZnSO

4

+H

2

One mole of Zinc reacts with sulphuric acid to form one mole of hydrogen.

Number of moles of Hydrogen gas formed can found out using PV=nRT.

P=520 mmHg i.e. 0.68 atm (1 atm = 760 mmHg)

V= 4.2 L

R = 0.0821

T = 279 K

Putting value in the equation n=0.125 mol.

So the mass of zinc reacted to form Hydrogen gas is 8.2 g of Zinc.

Purity of the compound is Actual mass/mass taken*100

=>8.2/12*100= 68%