Hard water


What ions cause hardness in water?


Which method can be used to remove temporary hardness but not permanent hardness from a sample of water?


What dissolved compound is responsible for causing temporary hardness in water?


A sample of tap water is tested for hardness. It is found that 23 cm3 of soap solution is needed to form a long-lasting lather. A sample of the same tap water is boiled, allowed to cool and then tested for hardness. The boiled sample required 17 cm3 of soap solution to form a long-lasting lather. What conclusion can be drawn about the type of hardness in this tap water?


Which statement correctly describes the method for determining the hardness of water?


Which of the following is a benefit of hard water?


Which water sample contains temporary hard water?

3 column table labelled Water sample, (A, B and C) and Volume of soap solution needed in cm cubed Before boliing and After boiling. The figures are A: 11.5 & 11.5, B: 2.5 & 2.5, C: 7.0 & 2.5.


What is the mean volume of soap added for sample B?

6 column table. Column 1 is labelled Sample. Columns 2-6 are labelled Volume of soap solution added in cm cubed and further divided into Test 1-4 and Mean. Figures for Row B are 11, 18, 12, and 13.


What can be used to identify whether a sample of water is hard or soft?


Which equation represents the symbol equation for the removal of temporary hardness from water?