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Testing the hardness of water

Description

Soap solution is used to measure the hardness of rain water, temporarily hard water and sea-water. The effect of boiling the hard water samples is investigated.

Credits

:
This is an experiment from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry.
testing-the-hardness-of-w...



Apparatus Chemicals

Eye protection

Measuring cylinders (10 cm3), 5 (one for each of A to E below)

Each group of students will need:

Conical flask (100 cm3)

Bung, to fit the conical flask

Burette and burette stand

Small funnel

Soap solution in IDA (Industrially Denatured Alcohol) (HIGHLY FLAMMABLE, HARMFUL), 75 cm3 per group (Note 1)

A supply of distilled or deionised water for rinsing their flask between experiments

Solutions as below, about 20 cm3 per group:

A Deionised water – labelled as Rain water

B A 50/50 mixture of temporarily and permanently hard water – labelled as Sea-water

C Temporarily hard water (Note 2) – labelled as Temporarily hard water

D Deionised water – labelled as Boiled temporarily hard water

E Permanently hard water diluted 50/50 with deionised water (Note 3) – labelled as Boiled sea-water

Refer to Health & Safety and Technical notes section below for additional information.

 


Soap solution in ‘ethanol’ (Industrial Denatured Alcohol, IDA – see CLEAPSS Hazcard, HIGHLY FLAMMABLE, HARMFUL) can be purchased or made up –






Soap solution is used to measure the hardness of rain water, temporarily hard water and sea-water. The effect of boiling the hard water samples is investigated.

ADDITIONAL INFORMATION

This is a resource from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry. This collection of over 200 practical activities demonstrates a wide range of chemical concepts and processes. Each activity contains comprehensive information for teachers and technicians, including full technical notes and step-by-step procedures. Practical Chemistry activities accompany Practical Physics and Practical Biology .