Sodium is a soft metal that can be cut easily with a table knife. Its density is so low that it will float when placed into water. At the same time, the metal is so active that it reacts violently with the water, producing sodium hydroxide and hydrogen gas as products. Sufficient heat is produced in the reaction to cause the metal to heat and to ignite the hydrogen produced in the reaction.

Sodium and Water Reaction

When sodium is cut using a knife that has been dipped in water, it results in a highly exothermic reaction. This is because sodium is a highly reactive metal, and when it comes into contact with water, it undergoes a vigorous reaction.

Reaction Mechanism

1. Formation of Sodium Hydroxide: Sodium reacts with water to form sodium hydroxide (NaOH) and hydrogen gas (H2). The reaction can be represented as follows:
2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)

2. Exothermic Nature: This reaction is highly exothermic, meaning it releases a significant amount of heat energy. The heat generated is sufficient to ignite the hydrogen gas produced, leading to a fire hazard.

Exothermic Reaction

1. Release of Heat: The reaction between sodium and water is so exothermic that it often causes the sodium to melt and form a small, fiery ball. This is due to the release of a large amount of heat energy.

2. Ignition of Hydrogen Gas: The hydrogen gas produced during the reaction is highly flammable. As the sodium reacts with water, the heat generated can ignite the hydrogen gas, resulting in a small explosion or a burst of flame.

3. Violent Reaction: The reaction between sodium and water is highly vigorous and can be described as a violent reaction. It produces a hissing sound, along with the release of hydrogen gas and the formation of sodium hydroxide.

Precautions

1. Use of Safety Measures: When handling sodium, it is essential to take proper safety precautions. Safety goggles, gloves, and a lab coat should be worn to protect against any potential hazards.

2. Handling Sodium with Dry Tools: Sodium should never come into direct contact with water or moisture. Using a knife that has been dipped in water can result in an uncontrolled reaction. It is advisable to use dry tools and equipment when working with sodium.

3. Disposal of Sodium Hydroxide: After the reaction, the resulting sodium hydroxide can be safely disposed of in an appropriate waste container. Proper care should be taken to prevent any contact with the skin or eyes.

In conclusion, cutting sodium using a knife that has been dipped in water will result in a highly exothermic and potentially dangerous reaction. It is crucial to handle sodium with extreme caution and follow all necessary safety measures to prevent any accidents or injuries.