I need to know step by step how to solve this kind of problem. Thanks! NaOH has

ID: 1039432 • Letter: I

Question

I need to know step by step how to solve this kind of problem. Thanks!

NaOH has a concentration of 0.0465. After traditional titration using 7-UP these were the results:

Volume of soda 40.90 mL Initial buret volume of NaOH 0.50 mL Final buret volume NaOH 20.81

Part 1.) Calculate the volume of NaOH used to reach end-point.

Part 2.) Calculate the moles of NaOH

Part 3.) Using the stoichiometry of the reaction of citric acid and NaOH calculate the moles of citric acid.

Part 4.) Calculate the molarity of citric acid

(1)

Volume of NaOH used = 20.81 - 0.50 = 20.31 mL

(2)

Moles of NaOH = molarity * volume in L = 0.0465 * 0.02031 = 0.000944 mol

(3)

Balanced neutralisation equation is,

H2C2O4 (aq.) + 2 NaOH (aq.) ----------> Na2C2O4 (aq.) + 2 H2O (l)

2 mol of NaOH neutralises 1 mol of H2C2O4

Then, 0.000944 mol of NaOH neutralises = 0.000944 * 1 / 2 = 0.000472 mol of H2C2O4

(4)

Molarity of H2C2O4 = moles / volume = 0.000472 / 0.04090 = 0.0115 mol/L