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What ions cause hardness in water?

Description

In this experiment the effect of dissolved salts, containing several different cations and anions, on the formation of a lather, is investigated.

Credits

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



Apparatus Chemicals

Eye protection

Each group of students will require:

Test-tubes, 8

Test-tube rack for 8 tubes

Beaker (100 or 150 cm3)

Dropping pipette

Bungs or corks, for test-tubes

Labels, for test-tubes

Soap solution in IDA (Industrially Denatured Alcohol) (HIGHLY FLAMMABLE, HARMFUL), 50 cm3 per group (Note 1)

Distilled or deionised water, 10 cm3 per group

The following solutions (all 0.1 M) in communal stock bottles, or beakers with dropping pipettes, 10 cm3 per group.

Sodium chloride

Calcium chloride

Magnesium chloride

Potassium nitrate(V)

Sodium sulfate(V)

Iron(II) sulfate(VI)

Magnesium sulfate(VI)

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 –






In this experiment the effect of dissolved salts, containing several different cations and anions, on the formation of a lather, 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.