Chemistry 2015-11-3 titration setup PDF

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Dr. Wojciechowicz's class...

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1 HOW TO SET UP A TITRATION Steps to set up a titration 1. Make a solution of KHP (dissolve 0.420 g KHP in 25.0 mL of d H2O) a. KHP—potassium hydrogen phthalate b. KHP + NaOH → 1:1 mole ratio c. Make sure all crystals are dissolved 2. Make NaOH solution (~0.10 M) a. Stock ~2.5 M because stock is more concentrated than solution b. Number of moles of NaOH will be the same for both dilute and concentrated solutions i. Dilution formula— MCVC = MdVd 1. MC—molarity of concentrated stock 2. VC—volume of stock 3. Md—desired molarity of dilute solution 4. Vd—desired volume for dilute solution mol of dilute solution moles of base∈concentrated stock liter ii. x L = x liters liters Ldilute 3. Make 250 mL of 0.10 M NaOH solution from a 2.5 M NaOH stock Vd = 250 mL MCVC = MdVd MdVd (0.10 M )(250 mL) = Md = 0.10.M VC = Mc 2.5 M MC = 2.5 M VC = 10 mL VC = ? 4. Take 10 mL of 2.5 M and add enough water to dilute up to 250 mL solution 5. KHP has a molar mass of 204.22 g/mol 1 mole KHP = 0.002056 mol KHP a. 0.420 g KHP x 204.22 g KHP 6. To fully neutralize KHP, you need 0.002056 mol NaOH a. Measure how much is needed to reach pale pink color 7. Take initial reading of ~0.10 M NaOH a. Initial = 0.70 mL 8. Since the number of moles of NaOH needed = 0.002056 mol NaOH in a volume = 30.65 mL, we can now find molarity of base (NaOH) solution 1L = 0.03056 L a. 30.56 mL x 1000 mL 0.002056 mol NaOH b. MNaOH = = 0.0673 M 0.03056 L 9. Take standardized NaOH solution to titrate a solution of vinegar (contains 5% acetic acid) a. Use titration volumes to calculate molarity of acetic acid in vinegar...