A sample of temporary hard water can be prepared in the laboratory by?
- disolving calcium chloride in distilled water
-
saturating lime water with carbon (IV) oxide
- saturating distilled water with calcium hydroxide
- dissolving sodium hydrogen trioxocarbonate (IV) in some distilled water
The correct answer is: B
Explanation
A sample of temporary hard water can be prepared in the laboratory by saturating lime water with carbon (IV) oxide. This means passing CO\(_2\) in excess through lime water, Ca(OH)\(_2\) to first obtain CaCO\(_3\), which later changes to soluble calcium hydrogentrioxocarbonate (IV) by passing more CO\(_2\) which imparts temporary hardness to water.
Ca(OH)\(_2\) + CO\(_2\) → CaCO\(_3\) + H\(_2\)O
CaCO\(_3\) + CO\(_2\) + H\(_2\)O → Ca(HCO\(_3\))\(_2\)