Testing water hardness (OCR Chem B, WJEC)

Testing water hardness

Soft water lathers easily with soap

Hard water does not lather easily with soap

Add a known amount of water sample to flask

Use burette to add a known amount of salt solution to flask

Stopper and shake the flask

If no lather is achieved, keep adding small amounts of soap solution and shaking

Record total volume of soap solution added

Compare the amount of soap solution needed to achieve a lather in different samples in order to compare their hardness