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(i) A very safe way of demonstrating the reaction of sodium and water is to drop a very
small piece of sodium into a swimming pool.
(ii) Pour a 2 cm layer of kerosene on to the surface of water in a test-tube. Drop a 3 mm
diameter piece of sodium into the kerosene. Be careful! Sodium sinks in the kerosene and
float in the water. Adjust the layer of kerosene to be shallow enough to allow the top of the
sodium to protrude above the surface. This reaction between sodium and the water is much
slower than if the sodium had been dropped directly on to the water. You can watch the
reaction through a hand lens held at the side, but never at the top. Sodium metal is lighter
than water but heavier than kerosene. A small area of the sodium suddenly reacts causing a
stream of bubbles to appear. The stream of bubbles at one side causes movement. The
irregular shape of the sodium changes to a sphere. The sodium melts because the reaction
gives off heat. Note any variations in light refraction and reflection below the sodium that
indicates something dissolving in the water. Slight smoke where the hot sodium is above the
kerosene level suggests a slight reaction with air. Test the gas bubbles for oxygen or
hydrogen.
sharon kalunda answered the question on April 12, 2019 at 08:34
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