Question

Lime water is a solution of:
a.) \[Ca{{(OH)}_{2}}\] in water
b.) \[CaC{{l}_{2}}\] in water
c.) NaOH in water
d.) NaCl in water

Answer 1

Hint: Pure lime water is clear and colorless and has a slight earthy smell and an alkaline bitter taste. The term lime refers to the alkaline mineral, which is unrelated to the acidic fruit.

Complete step by step solution:

Lime water is a common name for a dilute solution of calcium hydroxide in water, generally calcium hydroxide is sparsely soluble in water.
Limewater can be prepared by mixing calcium hydroxide (\[Ca{{(OH)}_{2}}\]) with water and removing the excess undissolved solute. When excess calcium hydroxide is added, a milky solution forms due to the homogeneous suspension of excess calcium hydroxide. This liquid has been known traditionally as Milk of lime.
Limewater is widely used by marine aquarists as a supplement of calcium.
Calcium hydroxide is produced commercially when we treat lime with water:
\[CaO\,+\,{{H}_{2}}O\,\to \,Ca{{(OH)}_{2}}\]
In the laboratory calcium hydroxide can be prepared by mixing aqueous solutions of calcium chloride and sodium hydroxide.
Let’s know why other options are not correct:
\[CaC{{l}_{2}}\] is a crystalline solid, which is also a salt and is readily soluble in water. It can be formed by neutralizing hydrochloric acid with calcium hydroxide.
NaOH is also called Caustic soda, it is highly soluble in water and easily absorbs moisture and carbon dioxide from water. On hydration it forms NaOH.n\[{{H}_{2}}O\]
NaCl is commonly known as salt, it is the most important salt for the salinity of seawater. Salt dissolves in water because the positive part of water molecules attracts the negative chloride ions and the negative part of water molecules attracts the positive sodium ions.

Note: Carbon dioxide reacts with lime water which is a solution of calcium hydroxide, to form a white precipitate (appears milky) of calcium carbonate (\[CaC{{O}_{3}}\]). Adding more carbon dioxide results in the precipitate dissolving to form a colorless solution of calcium hydrogen carbonate.