2. What does this imply for the size of the equilibrium constant for this reaction? CH;COOH(s) C6H;COOH(aq) 3. Benzoic acid can dissociate in water: CgH3COOH(a9) =C,H;CO0(1q) + H*(aq)¯ What effect would removing H* by reacting it with OH- to form water have on this equilibrium? Do your observations from test tubes 2, 3, and 4 support this? 4. What is the dominant form of benzoie acid in euch of the test tubes (C,HŞCOOH(8), C,H5COOH(aq), or CgHsCO0 (aq))? Test tube 1: Test tube 2: Test tube 3: Test tube 4:
Part C – Acid–base and solubility equilibria
1. Rinse 4 regular size test tubes and a 10 mL measuring cylinder thoroughly with water. Number the test-tubes from 1 to 4 in a test tube rack.
2. Into each of test tubes 1 – 3 put a small amount of solid benzoic acid (put the same amount – about the size of a pea – in each test tube).
3. Add 2 mL (use the measuring cylinder) of water to tube 1 and shake to mix the contents.
4. Add 2 mL (measuring cylinder) of 2 M HNO3 to tube 2 and shake to mix the contents.
5. Rinse the measuring cylinder with water, then use it to add 2 mL of 2 M NaOH to tube 3 and shake for about 10 seconds to mix the contents. Rinse the measuring cylinder.
6. Pour about half of the solution from tube 3 into tube 4, than add 2 mL of 2 M HNO3 to tube 4.
7. Allow the test tubes to stand for 2 or 3 minutes then record the appearance of the mixtures in each test tube.
8. Answer the questions on the results page relating to this equilibrium system.
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