2.5335g was the offical weight of Na2CO3 used. .038 L of H2SO4 was used for the

Question

2.5335g was the offical weight of Na2CO3 used.

.038 L of H2SO4 was used for the first titration.

Calculate the molarity of the H2SO4.

Reagents: sodium carbonate, approximately 0.05 N: Place 2.5 ± 0.2 g (record to the nearest 0.1 mg) Na2CO3 (dried at 250°C for 4 hours and cooled in desiccator) into a 1.0 liter volumetric flask and dilute to the mark. Calculate the exact concentration Sulfuric acid, 0.100 N: Dilute 3.0 mL conc H2SO4 to 1 liter with DI water. Dilute Sulfuric Acid 0.02 N: Dilute 200.0 mL of 0.100 N acid to 1 liter with DI water. Procedure: Standardization of Sulfuric Acid .Use an appropriate sized titration vessel to keep the air space above the solution at a minimum. Standardize the dilute H2S04 by pipetting 10.0 mL of 0.05 N Na2CO3 solution into a 150 ml beaker Add about 60 mL DI water. Add the titrant in 1.0 mL increments and record the volume added and the pH after each addition. Titrate to pH of about 5, the lift the electrode and rinse into beaker. Boil solution gently for 3-5 minutes under a watch glass cover. Cool to room until the pH is about 2. Repeat with two additional samples.

Explanation / Answer

Molarity of Na2CO3= wt. of Na2CO3 / M.wt. of Na2CO3                      M.wt. of Na2CO3= 105.988 g/mol

Molarity of Na2CO3= 2.5335 / 105.988= 0.0239 M

Molarity of H2SO4= (wt. of Na2CO3 x vol. of H2SO4) / M.wt. of Na2CO3 = 0.0009 M

vol. of H2SO4= 0.038 L

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