JAMB - Chemistry (2015 - No. 43)
The furring of kettles is caused by the presence of what compound in water?
calcium tetraoxosulphate (IV)
calcium hydrogentrioxocarbonate (IV)
calcium hydroxide
calcium trioxocarbonate (IV)
Explication
Calcium hydrogen carbonate, often present in temporary hard water, is boiled in a kettle to remove the hardness. In the process, a scale forms on the inside of the kettle in a process known as furring of kettles. This scale is composed of calcium carbonate.