Sodium carbonate is a reagent that may be used to standardize acids. In such a standardization it was found that a 0.498-g sample of sodium carbonate required 21.3 mL of a sulfuric acid solution to reach the endpoint for the reaction.

Na2CO3 (aq) + H2SO4 (aq) → H2O (l) + CO2 (g) + Na2SO4 (aq)

What is the molarity of the H2SO4?

The molarity of H2SO4 is 0.221 M

Explanation:

Step 1: Data given

Mass of sodium carbonate (Na2CO3) = 0.498 grams

Molar mass Na2CO3 = 105.99 g/mol

Volume of sulfuric acid (H2SO4) = 21.3 mL = 0.0213 L

Step 2: The balanced equation

Na2CO3 (aq) + H2SO4 (aq) → H2O (l) + CO2 (g) + Na2SO4 (aq)

Step 3: Calculate moles Na2CO3

Moles Na2CO3 = 0.498 grams / 105.99 g/mol

Moles Na2CO3 = 0.00470 moles

Step 4: Calculate moles H2SO4

For 1 mol Na2CO3 we need 1 mol H2SO4 to react and produce 1 mol H2O, 1 mol CO2 and 1 mol Na2SO4

For 0.00470 moles Na2CO3 we need 0.00470 moles H2SO4 to react

Step 5: Calculate molarity of H2SO4

Molarity H2SO4 =moles H2SO4 / volume

Molarity H2SO4 = 0.00470 / 0.0213 L

Molarity H2SO4 = 0.221 M

The molarity of H2SO4 is 0.221 M