An excess of sodium bicarbonate was added to 125 g of sulfuric acid solution. the total volume of released

An excess of sodium bicarbonate was added to 125 g of sulfuric acid solution. the total volume of released gas was 11.2 liters. Determine the mass fraction of sulfuric acid in the solution.

The mass fraction of a substance in a solution is determined by the formula:

w = m (substance): m (solution) x 100%.

It is necessary to find the mass of the substance (sulfuric acid). mass is calculated by the formula

m = n × M, where M is molar mass.

Before you can find the amount of acid substance, you need to find the amount of carbon dioxide.

1.Let’s find the amount of substance CO2.

V = Vn n, where Vn is the molar volume of gas, equal to 22.4 l / mol, and n is the amount of substance.

n = V: Vn

n (CO2) = 11.2 L: 22.4 L / mol = 0.5 mol.

2. Let’s compose the reaction equation, find the quantitative ratios of acid and carbon dioxide.

H2SO4 + 2NaHCO3 = Na2SO4 + 2CO2 + 2H2O.

For 1 mol of sulfuric acid, there are 2 mol of CO2.

The amount of sulfuric acid substance will be 2 times less than the amount of carbon dioxide substance.

n (H2SO4) = 0.5 mol: 2 = 0.25 mol.

Or:

1 mol (H2SO4) – 2 mol (CO2),

x mol (H2SO4) – 0.5 mol (CO2),

n mol (H2SO4) = (0.5 mol × 1 mol): 2 = 0.25 mol.

3.Let’s find the mass of sulfuric acid.

m = n × M,

M (H2SO4) = 1 × 2 + 32 + 16 × 4 = 98 g / mol.

m = 0.25 × 98 g / mol = 24.5 g.

4. Let’s find the mass fraction of sulfuric acid in the solution.

w = m (substance): m (solution) x 100%.

w = (24.5 g: 125 g) × 100% = 19.6%.

Answer: w (H2SO4) = 19.6%.