Hydrogen peroxide and sodium chloride are substances that react with water and absorb heat. Hydrogen peroxide, when mixed with water, decomposes into water and oxygen, releasing heat. Sodium chloride, commonly known as table salt, dissolves in water endothermically, absorbing heat from the surroundings.

Hydrogen peroxide (H2O2) reacts with water through a catalytic decomposition process, where the catalyst, often manganese dioxide (MnO2), speeds up the reaction. The chemical equation for this reaction is:

2 H2O2 → 2 H2O + O2

This reaction releases a significant amount of heat, making hydrogen peroxide a powerful oxidizing agent. The heat generated can be measured at around 150-160 degrees Celsius (302-320 degrees Fahrenheit) under ideal conditions.

Sodium chloride (NaCl) dissolves in water through an endothermic process, where the ionic bonds between sodium and chloride ions are broken, and new bonds are formed with water molecules. The dissolution process can be represented by the following equation:

NaCl (s) → Na+ (aq) + Cl

(aq)

The dissolution of sodium chloride in water is endothermic, meaning it absorbs heat from the surroundings. This is why adding salt to ice can cause the ice to melt faster, as the heat required for the dissolution process is taken from the ice, lowering its temperature.

The heat absorption during the dissolution of sodium chloride is relatively low compared to the heat released during the decomposition of hydrogen peroxide. However, it is still significant enough to be noticeable in everyday applications, such as in the melting of ice.

In conclusion, hydrogen peroxide and sodium chloride are substances that react with water and absorb heat. The decomposition of hydrogen peroxide is an exothermic reaction that releases heat, while the dissolution of sodium chloride is an endothermic process that absorbs heat. These properties make both substances valuable in various applications, including as cleaning agents and in the food industry.