Question

To standardize a hydrochloric acid solution, it was used as a titrant with a solid sample of sodium hydrogen carbonate, NaHCO3. The solid sample had a mass of 0.3967g, and 41.77 mL of acid was required to reach the equivalence point. Calculate the concentration of the standard solution.

Answer 1

0.113 M

Step-by-step explanation:

The reaction that takes place is:

• NaHCO₃ + HCl →NaCl + CO₂ + H₂O

First we convert 0.3967 g of NaHCO₃ into moles, using its molar mass:

• 0.3967 g ÷ 84 g/mol = 4.72x10⁻³ mol NaHCO₃

As 1 mol of NaHCO₃ reacts with 1 mol of HCl, in 41.77 mL of the HCl solution there were 4.72x10⁻³ moles of HCl.

With the calculated number of moles and the given volume we calculate the concentration of the solution:

• Converting 41.77 mL ⇒ 41.77 mL / 1000 = 0.04177 L

• Concentration = 4.72x10⁻³ mol / 0.04177 L = 0.113 M