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Titration. Standardization of a Base. Purpose: To standardize an NaOH solution using the primary standard KHP. KHP is an abbreviation for Potassium Hydrogen Phthalate (KHC 8 H 4 O 4 ) with a gfw of 204.22 g/mol. Cleaning the Buret. 1. Turn buret right side up and make sure valve is closed.
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Standardization of a Base • Purpose: To standardize an NaOH solution using the primary standard KHP. KHP is an abbreviation for Potassium Hydrogen Phthalate (KHC8H4O4) with a gfw of 204.22 g/mol.
Cleaning the Buret • 1. Turn buret right side up and make sure valve is closed. • 2. Rinse buret with about 10 mL of distilled H2O and run into waste beaker. • 3. Repeat step 2 for a total of 3 times. • 4. Rinse buret with about 10 mL of base and run into waste beaker. • 5. Repeat step 4 for a total of 3 times.
Procedure • 1. Measure 1.4-1.6 g of KHP into a weigh dish and transfer to a 50 mL erlenmeyer flask • 2. Fill a 50 mL buret with NaOH after cleaning it • 3. Add about 5 mL of distilled water and 2-3 drops of phenolphthalein to acid in flask • 4. SLOWLY add NaOH to acid while swirling flask • 5. The endpoint is reached when 1 drop NaOH turns the solution the lightest pink (make sure all of the acid has dissolved- you might have to use a warm hotplate to ensure all of it is gone.) • 6. Record the volume of base used (mL) • 7. Refill buret and repeat 2 more times
Data • TRIAL 1-2-3 • Mass of the KHP _____ • Volume of NaOH used _____ • The GFW of KHP 204.23 g/mol • The moles of KHP = the moles of base • Find the Molarity of the base
MM of an unknown Acid • Purpose: To determine the molecular weight of an unknown acid by titrating it with a standardized base
Procedure • 1. Mass between .5-.7 gram of the acid in a weigh dish and place it in an erlenmeyer flask • 2. Add about 5 mL of distilled water and 2-3 drops of phenolphthalein to the flask • 3. Fill a cleaned 50 mL buret completely with NaOH solution • 4. Add NaOH until 1 drop turns the solution light pink (make sure all of the acid has dissolved) • 5. Record the volume of base used • 6. Refill buret and repeat 2 more times times
Data • TRIAL 1-2-3 • Molarity of base (from part A)_____ • Mass of acid _____ • Volume of base _____