Materials: milk of magnesia, magnetic stirrer, 3 M HCl, universalindicator sol'n, and a large beaker.
Procedure: Place 50 to 100 ml. of the milk of magnesia in the beakerwith several drops of univ. ind. and about 200 ml of cold water. Start thestirrer and add the acid in small portions until the magnesium hydroxidedissolves.
Discussion: You can discuss the changes in pH (the pH drops aftereach addition of acid and then increases as more magnesium hydroxide dissolves).
The shifting equilibrium system (and Ksp factors) can also leadto interesting topics for discussion.
This is an acid base demo presented at an A.P. workshop (I am surprised Ihad not seen it before). It is quite simple and the discussion canbe taken in many directions.
Contributed by Annis Hapkiewicz