Lactic acid (HC₃H₅O₃)is a monoprotic acid that forms when milk becomes sour. A 40.00 mL sample of an aqueous lactic acid solution required 26.50 mL of 0.140 M NaOH(aq)to neutralize it by a titration. From this data, what is the molar concentration of lactic acid in the solution? Hint: Write out the equation and be sure to use the correct units when dealing with molarity.

Question

Quizplus · Accepted Answer

The balanced chemical equation for the reaction is:HC3H5O3(aq) + NaOH(aq) → NaC3H5O3(aq) + H2O(l)From the equation, we see that 1 mole of lactic acid reacts with 1 mole of NaOH.The number of moles of NaOH used in the titration is:moles of NaOH = Molarity of NaOH × Volume of NaOH used= 0.140 M × 0.02650 L= 0.00371 molTherefore, the number of moles of lactic acid in the 40.00 mL sample is also 0.00371 mol.The molar concentration of lactic acid in the solution is:Molarity of lactic acid = moles of lactic acid / Volume of lactic acid solution= 0.00371 mol / 0.04000 L= 0.0928 MTherefore, the correct answer is A) 0.0928 M.

Lactic Acid (HC3H5O3)is a Monoprotic Acid That Forms When Milk

Lactic Acid (HC₃H₅O₃)is a Monoprotic Acid That Forms When Milk