Solution of different salts Food flavouring, Make chlorine bleach Sea water contains Solution of different salts uses Main components Water Sodium chloride Impure powder Pure crystal by by by Distillation ( boils the sea water, then water turns to vapour, vapour is condensed back to liquid by cooling and is collected. Filtration (remove insoluble impurities) Natural evaporation (large industry) filtration Evaporate some water so to form a saturated solution Evaporate the solution until dryness. By Directly heating/heat with steam bath Crystallization (cool at room temp slowly) -- as temp decreases, solubility of salt decreases, some salt cannot dissolve anymore, crystal is formed. Dried the crystal by filter paper Filtration (filter the crystal from the mixture )

Filtration of sea water. glass rod sea water folded filter paper Residue (sand / mud) filter funnel Filtrate (clear sea water) stand Filtration of sea water.

Performing evaporation in the school laboratory… sea water heat steam water wire gauze tripod evaporating basin (a) Direct heating (b) Heating with a steam-bath

solution saturated with respect to sodium chloride Filtered sea water sodium chloride crystals sodium chloride crystals more concentrated solution water slowly evaporates at room temperature

Solution of different salts Food flavouring, Make chlorine bleach Sea water contains Solution of different salts uses Main components Water Sodium chloride Impure powder Pure crystal by by by Distillation ( boils the sea water, then water turns to vapour, vapour is condensed back to liquid by cooling and is collected. Filtration (remove insoluble impurities) Natural evaporation (large industry) filtration Evaporate some water so to form a saturated solution Evaporate the solution until dryness. By Directly heating/heat with steam bath Crystallization (cool at room temp slowly) -- as temp decreases, solubility of salt decreases, some salt cannot dissolve anymore, crystal is formed. Dried the crystal by filter paper Filtration (filter the crystal from the mixture )

Distillation using simple apparatus. thermometer clamp delivery tube end of delivery tube should be above the distillate delivery tube receiver test tube pure water (distillate) heat boiling tube clamp thermometer water (cooling agent) sea water anti-bumping granule (ensure smooth boiling)

Distillation using ‘Quickfit’ apparatus. thermometer heat thermometer pear-shaped flask anti-bumping granule solution water condenser receiver adaptor test tube (as receiver) cold water in (from tap) water out (to sink) thermometer bulb distillate cold water

Solution of different salts Sea water Boil at sharp 100oC (boiling point test) Pure water contains Solution of different salts Main components Water Sodium chloride Sodium ions Chloride ions (in solution form) Tested by Tested by Anhydrous copper(II) sulphate Dry cobalt chloride paper Flame test Tested by Silver nitrate solution White to blue Blue to pink Excess dilute nitric acid White precipitate fomed

Testing the presence of sodium ions in sodium chloride By flame test

Step 2 Dip the wire into a crushed sample (or solution) of the salt to be tested. non-luminous flame sample of the salt to be tested

Heat the end of the wire strongly in a non- luminous flame. Step 3 Heat the end of the wire strongly in a non- luminous flame. flame colour due to metal ions

The results of flame test of some metal compounds are as follows: Compound containing Flame colour Potassium ion Lilac Sodium ion Brilliant golden yellow Calcium ion Brick-red Copper(II) ion Bluish green

Potassium nitrate Calcium chloride Copper(II) sulphate Sodium carbonate

Moisten a clean platinum wire with concentrated hydrochloric acid. Step 1 Moisten a clean platinum wire with concentrated hydrochloric acid. platinum wire concentrated hydrochloric acid

Test for chloride ions white precipitate of silver chloride sea water add silver nitrate solution, followed by excess dilute nitric acid Fig.3.16 Silver nitrate test for the presence of chloride ions.

+ + sodium chloride silver chloride silver nitrate sodium nitrate (white precipitate) silver chloride + silver nitrate + sodium nitrate