Question

A solution of HNO3 is standardized by reaction with pure sodium carbonate.

2H+ + Na2CO3 -----> 2Na + H2O + CO2

A volume of 26.55 ± 0.05 mL of HNO3 solution was required for complete reaction with 0.8792 ± 0.0009 g of Na2CO3, (FM 105.988 ± 0.001). Find the molarity of the HNO3 and its absolute uncertainty

Answer 1

mass Na₂CO₃ = 0.8792 +/- 0.0009 g

molar mass Na₂CO₃ = 105.988 +/- 0.001 g/mol

moles Na₂CO₃ = (mass Na₂CO₃) / (molar mass Na₂CO₃)

moles Na₂CO₃ = (0.8792 +/- 0.0009 g) / (105.988 +/- 0.001 g/mol)

moles Na₂CO₃ = 0.008295 +/- 0.0000085 mol

moles H⁺ = 2 * (moles Na₂CO₃)

moles H⁺ = 2 * (0.008295 +/- 0.0000085 mol)

moles H⁺ = 0.01659 +/- 0.000019 mol

molarity HNO₃ = (moles H⁺) / (volume HNO₃ in Liter)

molarity HNO₃ = (0.01659 +/- 0.000019 mol) / (0.02655 +/- 0.000050 L)

molarity HNO₃ = 0.6249 +/- 0.0014 M