Question

To measure the amount of citric acid (C,H,O(CO,H), in a certain candy, an analytical chemist dissolves a 14.0 g sample of the candy in 150 ml. of water and titrates this solution to the endpoint with 10.6 ml. of 0.2500 M sodium hydroxide (NaOH) solution. The balanced chemical equation for the reaction is: C,H,0(CO,H) (aq) + 30H" (ag) - CH.0(CO) " (aq) + 3H20 (1) Oprecipitation acid-base O redox PO X 5 What kind of reaction is this? ? If you said this was a precipitation reaction, enter the chemical formula of the precipitate. If you said this was an acid-base reaction, enter the chemical formula of the reactant that is acting as the base. If you said this was a redox reaction, enter the chemical symbol of the element that is oxidized. Calculate the mass percent of C,H,OCO,H), in the sample. Be sure your answer has the correct number of significant digits.

Answer 1

A) Citric acid + NaOH - This acid base neutralization reaction and products are salt and water.

B) Chemical formula of base - NaOH

C) Moles of NaOH = molarity * volume in liters = 0.2500 * 10.6/1000 = 0.00265 moles

Since, NaOH is strong base. Thus,

Moles of OH- = moles of NaOH = 0.00265

From reaction;

3 moles OH- is required for 1 mole citric acid.

So, 0.00265 moles of OH- will be required for = 1*0.00265/3 = 0.0008833 moles of citric acid

Mass of citric acid = moles * molar mass = 0.0008833 * 192.124 = 0.16971 grams

% of citric acid in sample candy = 0.16971*100/14 = 1.212% OR 1.21% ....Answer

Let me know if any doubts.