Unit 1 Topic 3-Water

Rain Water-Low Ph,dissolved Carbon Dioxide,Oxgen gas dissolves.

Ground Water-(Hard water)Contains Calcium and Magnesium ions,dissolves when streams and rivers flow over rocks containing Calcium and Magnesium ions e.g. Gypsum.

Limestone-Causes hardness in water,mainly contains Calcium Carbonate-Practically insoluble.

Calcium Carbonate-Slightly acidic rain,Calcium Hydrogencarbonate formed in soluble water,Calcium ions therefore get into the water making it hard.

1:Heat the Ethanol and water mixture in a round bottom flask.

2:Watch the Ethanol evaporate at 78c it rises up to the condenser.

3:The condenser turns the Ethanol vapour back into a liquid.

4:The Ethanol is collected in the conical flask.

Water is know as Universal solvent.

A chemical that dissolves in a solvent is called a solute.

When no more solute can dissolve in the solvent it's called saturation.

Solubility is measure in g/100g.

Methood 1:

1:Measure 10g of a solute.

2:Add solute to 100cm3 volume of water.

3:Stir with glass rod until no more solute is seen to dissolve.

4:Filter using a funnel and filter paper.

5:Leave filtered solute to dry.

6:Once dry,weigh excess solute.

7:Calculate solibility,by finding out how much solute did dissolve.

Methood 2:

1:Measure 100cm3 water into a beaker.

2:Begin adding the solute bit by bit,stiring with a glass rod adding until no more will dissolve.

3:Heat the solution until all solute dissolves.

4:Allow to cool,record temperature at which crystal first appears.

The types of rocks found in different regions,determains how hard or soft the water will be.

Low levels of Calcium and Magnesium compounds make water softer.

High levels of Calcium and Magnesium compounds make water hard.

How hard water wastes soap-Expensive because you need to use more soap.Before dirt is removed.Some of the soap is wasted reacting with Calcium and Magnesium ions in the water-Forms insoluble salt that appears as scum.Soap can lather when all the ions have reacted.

1:Measure 50cm3 of water sample A into a conical flask.

2:Fill burette with soap solution.

3:Use burette to add 1cm3 of soap solution,insert bung shake vigorously for 5 seconds.

3:Repeat steps 2 and 3,until a lather forms and holds for 30seconds.

4:Record total of soap used.

5:Repeat for other samples.

7:Construct a bar graph.Use results to identify the type of water.

Temporary hardness can be removed by boiling the water.This leads to "Furing" of the kettles elements.

Calcium and Magnesium ions from salt,such as sulfates,are not removed by heating.The water remains hard even after boiling. Method 1-Using washing soda:Water soda is know also as Sodium Carbonate.When washing soda is added to hard water the Soluble Carbonate ions precipitate out Calcium and Magnesium ions.Dissolves metal ions from insoluble Carbonates.                                                                                      

Method 2-Using and ion exchange column:A column usually contains resin packed with Sodium ions.The hard water passes through the column,Sodium Ions exchange with Ca2+ or Mg2+.Some column work by swapping Hydrogen ions for Aquaeous Calcium or Magnesium ions.

Ca2+(ag)+Na2Co3 - CaCo3(5)

Hardess Washing Soda Limescale-Reduce efficent of appliences

Advantages:

Fast

Easy

Disadvantages:

Only works on temporary hard water.

Batch process.

Produces limescale-Reduce efficency.

Advantage:

Easy.

Cheap on a small scale.

Works on permedant hard water.

Disadvantages:

Produces limescale.

Sodium ions are made in the process-Effects health.

Advantages:

Works on permandent hard water.

Works on a large scale.

Continuous.

Disadvantages:

Expensive.

Resin need to be topped up with sodium ions.

Advantages:

Calcium Hydrocarbonate.

Dissolve Calcium.

Disadvantages:

Can cause Limescale.

Expensive.

1:Reserviors-Groundwater,rivers provide water to reserviors.

2:Sedimentation-Water stored in reserviors.Solid settle to bottom.

3:Filteration-Small particles are removed.

4:Chlorination-Kill bacteria.

5:Clean water stored in tanks and water towers.

6:Water passes along pipes to homes.

Flouride ions are added to strenghten childrens teeth in some areas.

Flouride is not added to water supplies in Wales.

Factories-Cooling machinery.

Hygiene-Keep clean.

Farms-To grown food.

Hydration-Drinking water.

If there is not enough rain some areas will expierence drought.

Water price may increase if further climate changes occur.

Decreasing water;

Do not allow water to run excessively.

Positives:

Strenghtens teeth.

Problems:

High concentrations-Cause cancer.

Discolouring of teeth.

Infertility

Good Luck.