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15 Cards in this Set
- Front
- Back
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Describe a chemical test for water |
A reversible reaction involving copper (II) sulfate can be used to test for water. When water is added to white anhydrous copper (II) sulfate it turns blue. Anhydrous cobalt chloride also changes from blue to pink when water is added. Cobalt chloride test papers are also used as a convenient test for water, but it could not determine its purity. |
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Describe and explain the purification of water supply |
To purify water, chlorination and filtration is used to get rid of the dirt, dissolved compounds and bacteria. The stages of chlorination is: 1. The water is passed though metal grids which collect objects such as twigs and leaves 2. In the sedimentation tank, particles of solid such as soil particles settle to the bottom of the tank 3. Aluminium sulfate is added to make small particles in the water stick together. The particles then fall to the bottom of the tank. 4. The water passes through a filter made of sand and gravel or crushed coal. Any small insoluble particles are removed. 5. Chlorine is added to kill bacteria. 6. The pH of the water is adjusted and the water is run off and stored or goes directly to homes and factories. |
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State some used of water in industry and in the home |
- In the home we use it for drinking, cooking, washing and cleaning - In industry is used as a solvent for many chemicals and as a coolant to stop industrial processes from getting too hot. It is also used as a cheap raw material for some chemical manufacturing processes. Water is also used to generate electrical power, either in hydroelectric power stations or by turning it into steam to drive turbines - In agriculture, water is used on farms for watering crops and animals to drink |
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Describe the composition of clean air |
- 78% Nitrogen - 21% Oxygen - 1% other gases ( mainly argon with small amounts of carbon dioxide, water vapour and other noble gases) |
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Describe the separation of oxygen and nitrogen from liquid air |
Oxygen and nitrogen can be separated from liquid air by using fractional distillation: 1. Water is removed from air by passing it through a drying agent and carbon dioxide is removed by reacting it with a sodium hydroxide solution 2. The air is cooled to -23C and compressed 3.The cold compressed air is allowed to expand into a larger space. When it expands, the air cools. The process is repeated until the temperature is -200C, and the air is mostly liquid. 4. Argon, neon and xenon are removed easily because they are still gases. A liquid mixture of nitrogen and oxygen is left. 5. When the liquid air is warmed, the nitrogen boils off first because it has a lower boiling point. Some of the nitrogen condenses at the top of the lower distillation column and leave a mixture of impure oxygen and nitrogen at the bottom. This mixture is then expanded to gas. 6. The gas mixture is the fed into the top column, where the temperature is below the boiling point of oxygen but above the boiling point of nitrogen. So the oxygen condenses at the bottom and nitrogen gas is removed from the top. |
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State the common air pollutants and describe their sources |
- Carbon monoxide -From the incomplete combustion of fuels - Sulfur dioxide - Fossil fuels, such as coal, oil and natural gases are burned, sulfur is oxidised and released as sulfur dioxide gas. - Volcanoes produce 1/3 or sulfure dioxide that pollutes the atmosphere - Oxides of nitrogen - Car engines - High-temperature furnaces - Electrical energy in lightning causes the formation of large amounts of nitrogen oxide and dioxide from nitrogen and oxygen in the air - Bacterial action in the soil can cause nitrate to be converted to nitrogen and nitrous oxide (denitrification) |
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Explain the presence of oxides of nitrogen in car exhausts and their catalytic removal. |
The high temperature and pressure inside an internal combustion engine causes nitrogen and oxygen to combine. A mixture of different nitrogen oxides are then formed. To remove carbon monoxide and nitrogen oxides, a catalytic converter can be fitted to a car exhaust to remove these two poisonous gases. - The exhaust gases from car engines are passed through a 'honeycomb' in the converter, which is covered with a thin layer of catalyst made of platinum, rhodium or palladium. The gases react on the surface of the catalyst, and the two gases are converted in two separate compartments into carbon dioxide, meaning it is no longer poisonous when released. |
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Explain why proportion of carbon dioxide in the atmosphere is increasing, and why this is important |
Carbon dioxide has been increasingly steadily, mostly due to burning fossil fuels in power stations and cars. Smaller amounts are also produced during industrial processes. CO2 is a greenhouse gas, and an increase in it can increase the effect of global warming. This is because CO2 will absorb heat from infrared rays, so more CO2 = more heat is absorbed, and when there is more heat re-radiated back to earth and less is lost into space, the atmosphere heats up more and causes global warming. |
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State the adverse effect of common air pollutants on buildings and on health. |
- Carbon monoxide is a poisonous gas can combines with haemoglobin in red blood cells, so the oxygen that is carried around the body is decreased. If someone gets CO poisoning, respiration in their cells will stop. - Lead compounds are particularly hazardous if it gets in our food or water supply or breathes, since it can build up in our body yet it is not easily removed. Even small quantities of lead can cause damage to the nervous system, especially in the brain of children. - Sulfur dioxide reacts with water vapour in the air to form a solution of sulfuric acid and causes acid rain. Acid rain can cause mass death of trees, lakes and rivers to become too acidic and aquatic life will die, soil may become too acidic to grow plants, metal structures will corrode, and building made up of carbonate rocks will erode ( especially ones made from limestone and marble) |
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Describe the various formations of carbon dioxide (hint: in the carbon cycle) |
- A product of complete combustion of carbon-containing substances - A product of respiration - A product of the reaction between and acid and a carbonate - A product of thermal decomposition |
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Describe the essential conditions (i.e. raw materials) for the Haber process |
The Haber process is used to manufacture ammonia Raw materials: - Hydrogen made from either natural gas or 'cracking' ethane. - To crack ethane a high temperature and a catalyst is needed - From natural gas a nickel catalyst with steam is used - Nitrogen extracted from the air |
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Describe the rusting of iron |
Rusting is the corrosion of iron and steel. Only they rust. - For rusting to occur, both oxygen and water are needed, and it is an oxidation reaction. - The water and oxygen in the air react together with the iron, and creates a weak layer of rust that soon flakes away and exposes a new surface. This surface will then start to rust |
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What are some simple methods of rust prevention? |
- Paint- for bridges and cars - A plastic coating- garden furniture and wire netting for fencing are often covered with plastic - Metal plating- Electroplating iron - Galvanising- specifically coating iron with zinc (used for roofing) - Greasing and oiling- used for tools and the moving parts of machinery |
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Describe the need for nitrogen-, phosphorus, and potassium-containing fertilisers. |
- Plants need nitrogen to make amino acids and proteins which encourage healthy growth. Potassium and phosphorus is also needed for healthy roots and leaves. - Nitrogen is an unreactive gas, so it is hard for plants to use. - These elements are normally removed from the soil when farmers harvest crops, but are not returned, which drecreases the overall amount of them in the soil and leads to poor growth of plants over time. So NPK fertilisers are needed. - These fertilisers add the substances to the soil to replace the elements taken up by plants. - It can replace essential elements, encourage growth and increase yields of crops. Otherwise, without fertilisers, plants could not grow healthily and supply our need. |
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Describe the displacement of ammonia from its salt. |
When ammonium salt is warmed with an alkali, ammonia gas is displaced from the salt and released. |
