Look at your mineral water label

• Where do the dissolved minerals come from? • How do you think the minerals affect the water?

Hard Water

We are learning to: • appreciate the problems associated with hard water areas.• use observation skills during a practical.

Scum and Scale

Scum: formed when soap reacts with hard water.

You need much more soap to make a lather with hard water, because it reacts with the calcium and magnesium ions in the hard water.

Sodium Stearate

(soap)

Ca2+ and Mg2+ ions

(from hard water)

+Calcium stearate and magnesium

stearate

(scum)

Na+ ions

(soluble in water)

+

Scum and Scale

Scale: formed when hard water is boiled.

Limescale can build up in kettles and heating systems. It makes them less efficient because limescale doesn’t conduct heat.

Ca2+

(from hard

water)

2HCO3- + CaCO3

(limescale)

H2O

(water)

+ CO2

(carbon

dioxide)

+

What sort of problems would hard water cause in the home?

Hard Water

We are learning to: • appreciate the problems associated with hard water areas.• use observation skills during a practical.