Air and water
Air and water
Are Core and Extended.
Questionnumber | Core: | Page Number |
1 | Describe chemical tests for water using cobalt (2) chloride and copper (2) sulfate | Describe methods of rust prevention, specially paint and other coatings to exclude oxygen | |
2 | Describe, in outline the treatment of the water supply in terms of filtration and chlorination. | Describe the need for nitrogen, phosphorus and potassium containing fertilizers | |
3 | Name some of the uses of water in the home | Describe the displacement of ammonia from its salts | |
4 | Describe the ...view middle of the document...
| Describe the carbon cycle, in simple terms, to include the processes of combustion, respiration and photosynthesis | |
Describe chemical tests for water using cobalt (2) chloride and copper (2) sulfate
For copper (2) sulfate
* Reaction no.1
When you heat blue crystals of copper (2) sulphate, they break down into anhydrous copper (2) sulphate, a white powder.
* Reaction no.2
The reaction is easy to reverse: by adding water. The white powder turns blue again. This is used to test for water:
CuSO4 (s)5H2O(l) →CuSO45H2O(s)
The water in blue copper (2) sulphate cyrstals is called: water of crystallization
The blue compound is hydrated.
The white compound is anhydrous
This test for water turns white anhydrous copper (2) sulphate blue
The equation for the reaction is:
This is a forward reaction. The blue crystals are to be heated to obtain the white powder, so the reaction is endothermic
This is the backward reaction. The white powder gets hot and spits when water is added, this reaction is exothermic.
For cobalt (2) chloride
It turns blue cobalt chloride paper pink. It is a reversible reaction.
Describe, in outline the treatment of the water supply in terms of filtration and chlorination
Filtration: is the liquid obtained from filtration where the solid has been removed
Chlorination: this is injected into water to kill microbes
A Modern Treatment Plant
1. The water is pumped in. A screen traps any big particles, such as twigs.
2. A coagulant is added – a chemical to make smell suspended particles stick together. It could be iron (3) sulphate, for example.
3. Next, air is blown through the water in floatation tanks, to make the coagulated particles float to the top. They are skimmed off.
4. The water is passed through a bed of fine sand to filter it.
5. It may go through further filters. For example more sand or charcoal to remove bad tastes and smells
6. Chlorine is added to kill the bacteria and other microbes
7. A fluoride compound is added in some plants, the help fight tooth decay
8. The water is pumped to the storage reservoir, ready for pumping to homes.
Diagram Fig. AW.1
Name some of the uses of water in industry and in the home
There is many ways that we use our water and that is partly why it is so important that we conserve our water.
Water is used for drinking, cooking, washing things, cleaning and for toilets.
They use it as a solvent and to wash things, to keep hot reaction tanks cool (cold water pipes are curled around the tanks).
Examples of industries that use water:
* Industries that produce metals
* Paper products
Describe the composition of clean air
* 79% of the air is...