Question

52g of impure HgCO3 sample is heated to form Hg, O2 and CO2. If percentage purity of sample is 80%,then the mass of Hg obtained is(atomic mass of Hg=200)

Answer 1

Answer: Mass of Hg obtained is 32 g.

Explanation: For a given reaction:

$2HgCO_3\overset{\Delta}{\rightarrow} 2Hg+O_2+2CO_2$

Molar mass of $HgCO_3$ = 260 g/mol

Molar mass of Hg = 200 g/mol (Given)

• For a 100 % pure sample,

By Stoichiometry

(2 × 260g) = 520 g of $HgCO_3$ will produce (2 × 200)g = 400 g of Hg.

52 g of $HgCO_3$ will produce = $\frac{400}{520}\times 52=40g$ of Hg.

• When the sample is 80 % pure

The amount of $HgCO_3$ present in the sample = 52 × 0.8 = 41.6 g

As, 52 g of $HgCO_3$ produces 40g of Hg.

So, 41.6 g of $HgCO_3$ will produce = $\frac{40}{52}\times 41.6 = 32g$

Hence, 32 grams of Hg will be obtained.

Answer 2

Answer:

Mass of Hg obtained is 32 g.

Explanation: For a given reaction:

Molar mass of  = 260 g/mol

Molar mass of Hg = 200 g/mol (Given)

For a 100 % pure sample,

By Stoichiometry

(2 × 260g) = 520 g of  will produce (2 × 200)g = 400 g of Hg.

52 g of  will produce =  of Hg.

When the sample is 80 % pure

The amount of  present in the sample = 52 × 0.8 = 41.6 g

As, 52 g of  produces 40g of Hg.

So, 41.6 g of  will produce =

Hence, 32 grams of Hg will be obtained.