Lab #10: Determining the Molar Mass of a Diprotic Acid December 2015

Part A: Standardizing the NaOH Solution Confirming the concentration of the NaOH solution that you will use in the next part: 1.Mass out 0.50g of citric acid, dissolve in 25 mL of water in an Erlenmeyer flask, add 2 drops of phenolphthalein and titrate with the NaOH. (It will take approx. 15 mL) 2.Repeat 2 x until results are reproducible. 3.Calculate the concentration of the NaOH solution. Create the neutralization reaction so that you are aware of the molar ratio. Citric acid is triprotic and hydrated: C 6 H 8 O 7. H 2 O

Part B: Determining the molar mass of an unknown diprotic acid (H 2 A) 1.Mass out 0.50 g of the acid, dissolve in 25 mL of water in an Erlenmeyer flask, add 2 drops of phenolphthalein and titrate with the same NaOH solution that you just standardized. 2.Repeat 2x or until your results are reproducible. 3.Calculate the molar mass of the unknown acid.

What you need to submit… All data collected in an organized chart. All neutralization reactions and calculations including proper use of significant digits, units NOTE: the unknown acid comes in the hydrated form. Percent water is 28.58%. Percent error