pH of Cement
Objective: The purpose of this demonstration is to show the reaction of water with cement and the accompanying change in pH.
Materials and Supplies:
- distilled water
- petri dish
- universal indicator or pH hydrion paper
- Fill a Petri dish half full of distilled water.
- If using universal indicator, place a drop in the water and mix. If solution is not yellow, add a drop of dilute acid to make it yellow. If using the pH paper, lay 2 strips on the bottom of the dish so the diameter of the dish is covered.
- Place the dish on the overhead.
- Into the solution or on top of the pH paper, place a spatula full of cement.
- Observe the change.
As the cement mixes with the water, hydroxide ions are formed, thus changing the indicator solution to blue. Emphasis should be placed on the fact that a chemical reaction is occurring not a dissolving process.