Question

what are the cause of hardness of water

Answer 1

Hi,

Referring to the hardness in water, it is caused by dissolved magnesium ions and calcium ions. These can get into the water when it comes into contact with limestone and other rocks that contain calcium/Magnecium compounds.

Hardness in the water can be distinguished in two ways:

Temporary hardness and permanent hardness.

Temporary hardness is due to hydrogen-carbonates of calcium and magnesium. When the water will be boiled, it decomposes to form calcium carbonate (as precipitation) and CO2. This removes the calcium ions or magnesium ions from the water, and so removes the hardness. Therefore, hardness due to hydrogen-carbonates is said to be temporary.

Hope you got your answer.

Answer 2

freezing or
decreasing in temperature