You compared the color of the solutions in three test tubes that initially contained 3 mL of 0.1 M ammonium hydroxide and a few

Question

3 years ago

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You compared the color of the solutions in three test tubes that initially contained 3 mL of 0.1 M ammonium hydroxide and a few

drops of phenolphthalein indicator. In a second test tube, you added 6 M NH4OH dropwise. Explain, in terms of the ammonia/ammonium ion equilibrium, why the phenolphthalein equilibrium shifted to the right?

Chemistry

1 answer:

WINSTONCH [101] · Answer 1 · 2022-08-21T17:53:53+03:00

Answer: The solution turns more intense pink.

Explanation:

In NH4OH, a delicate ammonia/ammonium equilibrium is set up as shown

NH4+. + OH-<----> NH3 +. H2O

As the concentration of NH4OH increases, the solution turns more intense pink since the equilibrium shifts towards the right and phenolphthalein moves towards the ionized form as more ammonia is produced from the equilibrium above making the solution more basic. The equilibrium shifts for phenolphthalein is shown in the image attached.