AIM
To perform and observe the action of water on quicklime and classifying the reaction.
MATERIALS REQUIRED
Calcium oxide, water, beaker, glass rod, dropper, red litmus paper, test tube, filter paper, funnel.
THEORY
1. Quick lime is (CaO). It is a white, caustic, alkaline, crystalline solid at room temperature.
Quicklime reacts with water to form calcium hydroxide. As in this reaction two substances – quicklime and water combine to form a new substance. Therefore, this reaction is called a combination reaction. This chemical change can be represented by the given chemical
equation :
During this chemical change, heat is also released. Therefore, this is an exothermic reaction.
PROCEDURE
1. Take some calcium oxide (quicklime) in the beaker and pour some water over quicklime slowly.
2. Stir the solution well with a clean glass rod and touch the outer surface of the beaker.
3. Take a clean dropper and put a drop of liquid solution a red litmus paper.
4. Filter the mixture of the beaker and take about 5 ml of filtrate in a test tube and blow air through the liquid.
OBSERVATION TABLE
The experimental procedure is described in the table :
S.No. |
Observation |
Inference |
1 |
A new substance is formed with a hissing sound. The outer surface of the beaker becomes hot. |
Water reacts with quicklime to form a new substance. As heat is evolved, the reaction between water and quick-lime is exothermic. |
2 |
Red litmus paper turns blue. |
The new substance formed by the combination reaction between water and quicklime is a base. |
3 |
On passing CO2 through the clear filtrate, it turns milky. |
The new substance formed by the reaction quick-lime and water is calcium hydroxide. |
RESULT
When quicklime and water combine to form calcium hydroxide and heat is released. Therefore this is an exothermic combination reaction.
PRECAUTIONS
1. Quicklime can cause severe burns. Therefore, it should be handled with a spatula.
2. Since the reaction is exothermic, water should be poured over quicklime slowly.
3. The filtrate collected should be removed.