Definitions [8]
The phenomenon due to which salt formed by a weak acid and a strong base, or by a strong acid and a weak base, dissolves in water to give an acidic or an alkaline solution, is known as hydrolysis.
Some salts absorb moisture (water vapour) from the atmosphere without dissolving in it. Such substances are called hygroscopic substances and the phenomenon is called hygroscopy.
Efflorescence is the property of some salts to lose wholly or partly their water of crystallisation when their crystals are exposed to dry air, even for a short time.
Certain water-soluble substances, when exposed to the atmosphere at ordinary temperature, absorb moisture from the atmospheric air to become moist, and ultimately dissolve in the absorbed water, forming a saturated solution. Such a substance is called a deliquescent substance, and the phenomenon is called deliquescence.
Dehydrating agents are substances that can remove water molecules even from compounds.
Some salts, unite with a definite quantity of water, which is known as the water of crystallisation.
On heating, crystals of sodium chloride produce a crackling sound, called decrepitation.
Certain substances remove moisture from other substances and are, called desiccants or desiccating agents or drying agents.
Key Points
- Salts conduct electricity when dissolved in water or molten form.
- Some salts contain water (water of crystallisation) and lose it on heating.
- Salts can be acidic, basic, or neutral depending on their parent acid and base.
- Most salts are water-soluble, and solubility changes with temperature.
