Question

The information provided below was obtained from the label of the commercial stock bottle of concentrated tetraoxosulphate (VI) acid. Calculate the volume of the acid that is needed to prepare 50 cm^3 of 0.5 moldm^-3 solution of the compound from the stock. Specific gravity of H2SO4 = 1.84 gcm^-3.

a) 15.8 cm^3
b) 27.2 cm^3
c) 36.4 cm^3
d) 42.1 cm^3

Answer 1

To make 50 cm³ of a 0.5 moldm⁻³ H2SO4 solution, 1.402 cm³ of concentrated sulfuric acid is needed from a stock solution with 95% purity and a density of 1.84 gcm⁻³.

Step-by-step explanation:

To calculate the volume of concentrated tetraoxosulphate (VI) acid (H2SO4) needed to prepare 50 cm³ of a 0.5 moldm⁻³ solution, we need to use the concept of molarity and dilution.

Step 1: Calculate the moles of H2SO4 required

Moles of H2SO4 = Molarity × Volume in dm³
= 0.5 mol dm⁻³ × 0.050 dm³
= 0.025 moles

Step 2: Calculate the mass of H2SO4 using its molar mass (Molar mass of H2SO4 = 98 g/mol)

Mass = Moles × Molar mass
= 0.025 moles × 98 g/mol
= 2.45 g

Step 3: Calculate the volume of stock solution needed, knowing the percentage purity and density

Volume = Mass / (Density × Percentage purity)
= 2.45 g / (1.84 gcm⁻³ × 0.95)
= 2.45 g / 1.748 gcm⁻³
= 1.402 cm³

To prepare 50 cm³ of a 0.5 moldm⁻³ solution from stock, we would need 1.402 cm³ of the concentrated acid.