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Reaction of calcium with water

Answer Text:
Calcium.
Procedure:
- A small piece of calcium metal is cut and dropped into a trough containing water;
- A filter funnel is inverted over it;
- A test tube filled with water is then inverted over the funnel;
- The gas given out is collected as shown in the apparatus below.
- The resultant gas is then tested with a burning splint;
- The resultant solution in the trough is tested with litmus paper.
Diagram of apparatus:

Observations and explanations:
- Calcium sinks to the bottom of the beaker; because it is denser than water;
- Slow effervescence of a colourless gas; due to slow evolution of hydrogen gas;
- Soapy solution formed; due to formation of alkaline calcium hydroxide;
- A white suspension is formed; because calcium hydroxide is slightly soluble in water;
Reaction equation:
`Ca(s) + H_2O (l) → Ca (OH)_ 2(aq) + H_2 (g)`;
Effect of resultant solution on litmus paper;
- Litmus paper slowly turns blue; calcium hydroxide formed is slightly soluble in water; releasing a small number of hydroxyl ions which result into alkaline conditions // high pH;