Unit 11: Air and Water Flashcards
What are two methods of testing for water?
- Water will turn anhydrous copper sulfate from white to blue.
- Water will turn anhydrous cobalt chloride from blue to pink.
How is the water supply purified?
- The water is filtered through coarse sand to remove the larger insoluble particles. It is then filtered through a finer sand.
- Chlorine gas is added to kill any remaining bacteria.
What are the uses of water used for industrial purposes?
Mainly for cooling and irrigation purposes.
What is the composition of air?
- 78% nitrogen
- 21% oxygen
- 1% a mixture of carbon dioxide and noble gases.
What are the main pollutants in the air?
- Carbon monoxide
- Sulfur dioxide (can contribute to acid rain)
- Oxides of nitrogen (can also contribute to acid rain)
- Lead compounds
What is the main source of the pollutant carbon monoxide?
The incomplete combustion of carbon containing substances.
What is the main source of the pollutant sulfur dioxide?
From the combustion of fossil fuels which contain sulfur compounds.
What is the main source of the polluting oxides of nitrogen?
From car engines.
What is the main source of the polluting lead compounds?
The combustion of leaded petrol.
What are the main affects of the pollutants in the air?
Acid rain can dissolve some cement products and the mortar in brick work, it can also attack some metals. Lead compounds and carbon monoxide are poisonous. Sulfur dioxide and nitrogen oxides can cause problems for asthmatics.
What are the conditions required for the rusting of iron?
Water and oxygen.
How can rusting and corrosion be prevented?
- Painting.
- Covering in grease.
- Plastic covering (mainly for wires).
- Plating in another metal.
How are oxygen and nitrogen separated from the air?
The air is compressed and cooled below the b.p. of both oxygen and nitrogen so the air becomes a liquid.
The air is allowed to warm slowly and the nitrogen boils off before the oxygen because it has a lower boiling point.
How are nitrogen oxides formed in car engines?
Under the high pressures and temperatures in the engines of motor vehicles, nitrogen and oxygen can combine to form oxides of nitrogen.
How are nitrogen oxides removed from car exhausts?
A catalytic converter converts the oxides of nitrogen into less harmful gases like nitrogen and carbon dioxide. Catalytic converters only work with unleaded petrol because lead will harm the catalytic converter.
What is sacrificial protection and how does it work?
Where iron is galvanised with zinc. Zinc is higher on the reactivity series so is more reactive than iron so will corrode and go into solution first, only when all of the zinc has corroded will the iron begin to rust.
Why are nitrogen, phosphorus and potassium fertilisers needed?
Plants need things like nitrogen to make plant proteins. It must be absorbed into the soil in a soluble form (ex. nitrates). When plants are harvested, this nitrogen is taken away from the soil in the plants, so the soil needs fertilisers to add these nutrients back to the soil.
How is ammonia displaced from its salts?
Look back at older topic.
What are the essential conditions for the manufacture of ammonia in the Haber process?
Look back at older topic.
How do carbon dioxide and methane contribute to climate change?
They interact with infrared radiation and slow down heat loss to space from the atmosphere, with more carbon dioxide and methane, less heat is escaping so temperatures are rising.
What are the ways in which carbon dioxide can be formed?
- As a product of the complete combustion of carbon-containing substances.
- As a product of respiration.
- As a product of the reaction between an acid and a carbonate.
- From the thermal decomposition of a carbonate.
What are the sources of methane?
- The decomposition of vegetation.
2. As a waste gas from digestion in animals.
What are the steps in the carbon cycle?
- Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
- Carbon dioxide is absorbed by producers to make carbohydrates in photosynthesis.
- Animals feed on the plant passing the carbon compounds along the food chain. They exhale carbon dioxide formed during respiration. The animals and plants eventually die.
- The dead organisms are eaten by decomposers and the carbon in their bodies is returned to the atmosphere as carbon dioxide. The plant and animal material may then be available as fossil fuel in the future for combustion.
What are some tests for ammonia?
- It turns damp red litmus blue.
2. It forms a white smoke when it reacts with hydrochloric acid fumes.