How does the formation of a solution involve energy?

Let's prepare two solutions: (a) an ammonium chloride solution in water; and (b) a sodium hydroxide solution in water.

(a) Measure the temperature of 100 milliliters of water in a beaker; this is known as the initial temperature.

(b) Melt 4 grams of ammonium chloride in 100 milliliters of water. Add the ammonium chloride and mix. Take note of the temperature of the mixture. This is known as the final temperature.

When ammonium chloride dissolves in water, it absorbs heat from the water, causing the water to lose heat and its temperature to decrease. This is an endothermic process because salt absorbs heat from the surrounding water. (c) In this experiment, you will notice that the temperature of the water will decrease (final temperature < initial temperature).

(a) Measure the temperature of 100 milliliters of water in a beaker; this is known as the initial temperature.

(b) Melt 4 grams of sodium hydroxide in 100 milliliters of water. Add the sodium hydroxide and mix. Take note of the temperature of the mixture. This is known as the final temperature.

When sodium hydroxide dissolves in water, heat is released into the water, increasing the temperature of the surrounding water. This is an exothermic process because salt releases heat into the surrounding water. (c) In this experiment, you will notice that the temperature of the water will increase (final temperature > initial temperature).

The formation of a solution involves energy in the form of either absorption or release of heat, depending on whether the process is endothermic or exothermic. This energy is required to overcome the intermolecular forces between solute particles and solvent particles, allowing them to mix and form a homogeneous mixture.