Postlab 3.docx - Practice Titration Potassium Hydrogen...

• 7

This preview shows page 1 - 4 out of 7 pages.

Practice Titration, Potassium Hydrogen Phthalate (KHP) Post Lab Quantitative observations Part 2: Titration (Standardization of NaOH solution) Trial 1 Trial 2 Trial 3 Mass of a weighing paper (or dish) (g) 0.2321g 0.2364g 0.2367g Mass of a weighing paper (or dish) and dried KHP (g) 0.9312g 0.9377g 0.9318g Mass of dried KHP (g) 0.6991g 0.7013g 0.6951g # of moles, KHP (mol) 0.003423 mol 0.003434 mol 0.003403 mol The volume of NaOH (Initial buret reading) (mL) 0.5mL 0.1mL 1.1mL The volume of NaOH (Final buret reading) (mL) 33.75mL 33.6mL 34.4mL The volume of NaOH used (mL) 33.3mL 33.5mL 33.3mL Molarity of the NaOH solution 0.103 mol/L 0.103 mol/L 0.102 mol/L
(mol/L) % Error 3% 3% 2% Average Molarity of the NaOH solution and STD : 0.103 mol/L ± 0.001 mol/L Mass of dried KHP: Trial 1: 0.9312g – 0.2321g = 0.6991g Trial 2: 0.9377g – 0.2364g = 0.7013g Trial 3: 0.9318g – 0.2367g = 0.6951g # of moles, KHP: Molecular weight = 204.24 g/mol Trial 1: 0.6991g x 1 mol 204.24 g = 0.003423 mol Trial 2: 0.7013g x 1 mol 204.24 g = 0.003434 mol Trial 3: 0.6951g x 1 mol 204.24 g = 0.003403 mol The volume of NaOH used: Trial 1: 33.75mL – 0.5mL = 33.3mL Trial 2: 33.6mL – 0.1mL = 33.5mL Trial 3: 34.4mL – 1.1mL = 33.3mL Molarity of the NaOH solution : moles of solute ( mol ) volumeof solution ( L ) , n NaOH = n KHP (1:1 ratio) Trial 1: 0.003423 mol x 1 33.3 mL 1 L 1000 mL = 0.103 mol/L
Trial 2: 0.003434 mol x 1 33.5 mL 1 L 1000 mL = 0.103 mol/L Trial 3: 0.003403 mol x 1 33.3 mL 1 L 1000 mL = 0.102 mol/L % Error: ¿ recorded value expected value ¿ expected value ¿ x 100% Trial 1: ¿ 0.103 mol L 0.1 mol L ¿ 0.1 mol L ¿ x 100% = 3% Trial 2: ¿ 0.103 mol L 0.1 mol L ¿ 0.1 mol L ¿ x 100% = 3% Trial 3: ¿ 0.102 mol L 0.1 mol L ¿ 0.1 mol L ¿ x 100% = 2% Average: 0.103 mol L + 0.103 mol L + 0.102 mol L 3 = ¿ 0.103 mol/L
• • • 