Hard Water L.O: To know what makes water hard, and the pros and cons associated with this

What do washing powder boxes tell you about hard and soft water?

Rain Water All rain water is slightly acid due to the CO 2 in the air but it is increased by … CO 2 – Burning fossil fuels and respiration (deforestation also reduces the earths ability to remove CO 2 )  Carbolic Acid SO 2 – Volcanoes and Power stations  Sulphuric Acid N 2 – Exhaust fumes  Nitric acid Acid rain kills plants and fish

As rain water runs over rocks it picks up other minerals Running over the limestone also causes other salts to dissolve e.g. calcium and magnesium Carbonic acid reats with limestone to create soluble calcium hydrogencarbonate Calcium carbonate (s) + Carbonic Acid (aq)  Calcium hydrogencarbonate (aq) CaCO 3 (s) + H 2 CO 3  Ca(HCO 3 ) 2 (aq) Water with these salts is called HARD WATER Water without these salts in called SOFT WATER

Hardness can be temporary or permanent. Temporary hardness is dues to calcium hydrogen carbonate. Temporary hardness may be removed by boiling because hydrogencarbonate ions form carbonate ions which react with calcium or magnesium to form precipitates Permanent hardness is caused by calcium and magnesium sulfates which cannot be removed by boiling Permanent and Temporary Hardness

Which areas would you expect to have high proportions of limestone?

How could you test how hard or soft water is?

Prove the hypothesis that more soap is needed for harder water. And that boiling temporary hard softens the water You will have water samples: softDistilled Temporary Hard A Boiled A Permanently Hard B Boiled B 10ml water, 1ml soap at a time Design a table to collect quantitative results in

Tap water in some parts of the country is very pure and is said to be ‘soft’. It easily makes a lather with soap. Water from other parts may contain various dissolved impurities and is described as ‘hard’ water. Temporary hardness may be removed by boiling, but permanent hardness survives the boiling process. In this practical activity, water hardness can be measured by finding out the volume of soap solution required to form a permanent lather with a known volume of water.

Is the rainwater hard or soft? Is the rainwater hard or soft? 2. Is seawater hard or soft? 2. Is seawater hard or soft? 3. Does seawater contain temporary hardness, permanent hardness or both? 3. Does seawater contain temporary hardness, permanent hardness or both? Water type to produceVolume of soap required a permanent lather /cm3 Rainwater0.5 Seawater4 Temporary hard water3 Seawater, boiled then cooled (permanent hard water) 3 Temporary hard water, boiled then cooled 1

HARD needs more soap! The compounds dissolved in hard water (Calcium ions) react with the soap, forming scum. The soap makes scum before it can cause lather. Sodium stearate (soap) + calcium ions  calcium stearate (scum) + sodium ions Hence harder water needs more soap.

HARD Vs SOFT WATER HARD WATER Does not lather easily with soap so wastes soap and money Forms a scum with soap Causes limescale which can reduce the efficiency of appliances BUT contains chemicals good for health and development of teeth and bones and can reduce heart disease. Also tastes better and is better for making beer!!! SOFT WATER Does not taste very nice Less health benefits BUT no limescale or scum and better for soap