A6.53 g sample of a mixture of magnesium carbonate and calcium carbonate is treated with excess hydrochloric acid. the resulting reaction produces 1.73 l of carbon dioxide gas at 26 ∘c and 745 torr pressure.
a)calculate the total number of moles of carbon dioxide that forms from these reactions.
express your answer using three significant figures.
b) assuming that the reactions are complete, calculate the percentage by mass of magnesium carbonate in the mixture.

0.069moles

45.65%

Explanation:

Firstly, we need to calculate the number of moles of CO2 produced. We can use the ideal gas equation for this.

PV = nRT

n = PV/RT

according to the question,

P = 746torr

V = 1.73L

T = 26 = 26 + 273.15 = 299.15K

n = ?

R = 62.364 L. Torr/k.mol

n = (746 * 1.73)/(62.364 * 299.15) = 0.069moles

B. To get this, we can use their molar masses. The molar mass of calcium carbonate is 100g/mol while for magnesium carbonate, molar mass is 84g/mol

The percentage by mass is (84)/(84 + 100) * 6.53g = 2.98g

= 2.98/6.53 * 100 = 45.65%