Question

Lactic acid, C3H6O3, is a monoprotic acid that is available in solid form. Determine the concentration of an unknown solution of sodium hydroxide, in moles per litre, given that it takes 18.34 mL to neutralize a solution containing 0.821 g of lactic acid. Write a balanced chemical equation for the reaction .

Answer 1

0.497 moles/L

Step-by-step explanation:

The reaction that takes place is:

• C₃H₆O₃ + NaOH → C₃H₅ONa + H₂O

First we calculate the moles of lactic acid in 0,821 g, using its molar mass:

• 0,821 g ÷ 90 g/mol = 9,122x10⁻³mol lactic acid

One mole of lactic acid reacts with one mole of sodium hydroxide (it is a monoprotic acid), so in 18,34 mL of NaOH solution there are 9,122x10⁻³moles of NaOH:

• 18.34 mL ÷ 1000 = 0,01834 L

• 9,122x10⁻³mol ÷ 0,01834 L = 0.497 moles/L