Question

Розгляньте малюнок «Взаємодія натрію з водою». У кристалізатор з водою додано індикатор — фенолфталеїн. Поясніть причину появи малинового кольору розчину.

Answer 1

Interaction of Sodium with Water and the Appearance of a Pink Color in the Solution

When sodium (Na) is added to water (H2O), a chemical reaction occurs. This reaction is highly exothermic, meaning it releases a significant amount of heat. The reaction can be represented by the following equation:

2Na + 2H2O -> 2NaOH + H2

In this reaction, sodium reacts with water to form sodium hydroxide (NaOH) and hydrogen gas (H2). The sodium hydroxide dissolves in water to form a solution.

The appearance of a pink color in the solution is due to the presence of an indicator called phenolphthalein. Phenolphthalein is a pH indicator that changes color depending on the acidity or alkalinity of a solution. In neutral or acidic solutions, phenolphthalein is colorless. However, in alkaline solutions, it turns pink or magenta.

When sodium reacts with water, it produces sodium hydroxide, which is an alkaline substance. The presence of sodium hydroxide in the solution causes the phenolphthalein indicator to change color, resulting in a pink color in the solution.

To summarize: - Sodium reacts with water to form sodium hydroxide and hydrogen gas. - Sodium hydroxide is an alkaline substance. - The presence of sodium hydroxide in the solution causes the phenolphthalein indicator to turn pink.

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