Answer:
0.497 moles/L
Explanation:
The reaction that takes place is:
First we calculate the moles of lactic acid in 0,821 g, using its molar mass:
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: