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GCSE: Changing Materials - The Earth and its Atmosphere
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Key things you need to know about the atmosphere
- 1 The air around us is composed of 70% nitrogen, 29% oxygen and 1% other gases (mostly noble gases and 0.04% carbon dioxide)
- 2 Two of the best ways now being used to reduce carbon dioxide emissions are: “capture and storage”- where we capture the CO2 and trap it in abandoned oil wells. And “sequestration”- where we react the CO2 with CaO to make CaCO3 (CaO + CO2 = CaCO3)
- 3 The layer of atmosphere that we live in is called the troposphere. Above that is the stratosphere, followed by the mesosphere, then the thermosphere and finally the exosphere. The ozone layer is located in the lower stratosphere.
- 4 The ozone layer is a layer of O3 molecules that absorb harmful ultraviolet radiation that would otherwise kill most human life on Earth (by giving us cancer).
- 5 Gases like CFC’s (chlorofluorocarbons) destroy the ozone layer. It takes decades for CFC’s to be removed from the atmosphere once they are up there- and all the time they are constantly destroying more ozone. There is currently a hole in the ozone layer caused by gases like CFC’s that is as big as the arctic (north) pole…and growing.
Five top tips on pollution
- 1 Carbon monoxide is a toxic gas as it blocks the haemoglobin in our blood from transporting oxygen around our body…if you take in too much carbon monoxide you will suffocate even if you keep on breathing!
- 2 Nitrogen oxide and nitrogen dioxide gases in the atmosphere cause acid rain. This destroys trees and makes lakes too acidic for fish to live in. It is also responsible for corroding buildings.
- 3 Carbon dioxide is the biggest cause of global warming and if its levels are not reduced, it could cause the melting of the polar ice caps. This will flood an estimated minimum of 30% of England. It is the biggest worry of atmospheric scientists of our time.
- 4 Particulates, mainly found in car exhausts, get stuck in our lungs and cause cancer.
- 5 Low level ozone (O3) is incredibly dangerous, especially for people who have asthma.
What is global warming?
- 1 Global warming is caused by greenhouse gases absorbing infrared radiation emitted from the Earth and scattering it back down to Earth. As infrared radiation is basically heat, this heats the surface of the Earth up.
- 2 As well as carbon dioxide, other greenhouse gases include water and methane. They absorb the infrared radiation by making their bonds vibrate.
- 3 As global warming causes the polar ice caps to melt, clathrate deposits (huge amount of trapped methane gas) are released. This causes further global warming in a positive feedback loop.
- 4 As the average temperature on land raises, many crops will not be able to grow. Almost all scientists agree that this will cause widespread famine on a scale never seen before. This will affect all countries, not just developing countries.
- 5 A common mistake students make is to confuse the greenhouse effect with the hole in the ozone layer. Ozone has nothing to do with the greenhouse effect. Keep these two topics clearly separated in your mind.
The destruction of the Amazon Rain Forest is an example that shows the deadly results of tampering with one of natures ecosystems. Methane gas emissions are trapped in the Earth's atmosphere and reflect light along with all other pollutants, adding to the destruction of the Ozone Layer. The energy burned to run automobiles, heat homes, factories and businesses is responsible for about eighty percent of society's carbon dioxide output. Global warming has been a concern for the past two decades with the increase of industrial pollution from major industrialised countries around the world.
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They are called fossil fuels because they are made from the remains of ancient plants and animals. They are formed very slowly over millions of years and are non-renewable  As the concentration of these gases grows, more heat is trapped by the atmosphere and less escapes back into space. This increase in trapped heat, changes the climate, causing different weather patterns that can bring extreme precipitation or dry spells and more severe storms.  What has the global warming done to the environment so far?
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When they reach it, the negatively charged cathode provides the electrons to "reduce" the positively charged ions to metallic form and create the plating. Plating is used to coat metals to avoid corrosion or resist abrasion as well as plating for a cosmetic finish. Michael Faraday, an English chemist and physicist discovered two relationships between the mass of metal produced at the cathode and the voltage passed through the cell. His first law of electrolysis states that the mass of a substance produced at an electrode during electrolysis is proportional to the number of moles of electrons (the quantity of electricity)
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Copper is a chemical element in the periodic table that has the symbol Cu and atomic number 29. Copper is a reddish-colored metal, with a high electrical and thermal conductivityCopper has its characteristic color because it reflects red and orange light and absorbs other frequencies in the visible spectrum, due to its band structureCopper is insoluble in water (H2O) as well as isopropanol, or isopropyl alcohol. There are two stable isotopes, 63Cu and 65Cu, along with a couple of dozen radioisotopes.
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GNVQ/Vocational Science - Reduction of Copper including methods of extracting metals (copper) in industry
Then separate the copper from the waste by half filling the test tube with water and pouring the mixture into a beaker of cold water. 7. Leave for two minutes and then pour off the dirty water. 8. Keep adding cold water to the mixture and pouring off the dirty water till you see pink copper at the bottom of the tube. 9. Put the copper onto filter paper to dry it. Measure the mass of dried copper - this is your actual yield.
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At the anode however, gas is usually collected, and is passed into the surrounding air. In my experiment I have chosen the copper sulphate solution to electrolyze. In the experiment when the solution is being electrolyzed it starts to decompose and at the positive cathode copper is formed, and makes a thin plating around it. At the anode however, oxygen is formed, and is released. This comes about because of the chemical change that has happened, as a result of the electricity being passed through and disrupting the ions, making them mix and collect at different electrodes depending on the polarity of the ions.
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To determine the value of Faraday constant (quantity of electricity per mole) by using electrolysis of Copper.
of moles = 228 / 0.00268 = 85200 C mol-1 (3 sig. fig.) 5) Discussion: When doing the experiment, there some precautions taken to minimize the number of possible errors. First of all, the copper foil cathode and anode were rubbed with sand paper to remove copper oxide which was formed by the reaction of copper and atmospheric oxygen on their surface. If the electrodes were not treated like this, the layer of copper oxide would hinder the electrolysis of copper.
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fixed * Length& width of metals * Time in which metal is in contact with electrolyte * Room Temperature SAFETY: To ensure that there is the optimum level of safety for me and others I must: Wear safety goggles to ensure that no sulphuric acid comes in contact with anyone's skin Make sure the sulphuric acid does not come in contact with anybody's skin as it corrosive. If this happen, immediately wash it off with water Results Table: Metals Amount of Voltage (Experiment 1)
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An investigation into whether the voltage affects the amount of gas produced during the electrolysis of sodium chloride solution.
Then I will have to multiply by 1000 to get the amount of hydrogen in cm�. Preliminary Voltage (v) Amount of hydrogen gas produced at the cathode (ml) Current (A) 4 1.8 0.77 5 2.8 1.24 11 8.2 2.88 Voltage (V) Time (S) Amount of hydrogen gas produced at the cathode (ML) 5 1 Approx 0.6 10 3 Too big to measure I am going to use voltages 5,6,7,8,9 and10 because for voltages lower than five there was not a lot of gas produced this made it extremely difficult to measure the amount of gas.
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I will be measuring the current in amps because it is easier to measure and read. Prediction: I predict that as the current increases, the mass of copper collected will increase. This is because more energy is present so the amount of ions in the electrolyte- copper sulphate solution- will increase and also the rate of electrolysis will increase. Copper Sulphate (CuSO4) is made up of 4 ions; Copper (II) ions (Cu2+), Sulphate ions (SO42-), Hydrogen ions (H+) and Hydroxide ions (OH-).
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I can therefore predict that if I double the time of the experiment, I will therefore be doubling the charge. This statement can be supported by both of Faraday�s Laws. Faraday�s First Law of electrolysis states that: �The mass of any element deposited during electrolysis is directly proportional to the number of coulombs of electricity passed� Faraday�s Second Law of electrolysis states that: �The mass of an element deposited by one Faraday of electricity is equal to the atomic mass in grams of the element divided by the number of electrons required to discharge one ion of the element.� Another
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I will not keep the power on more than 10 minutes, as keeping the power on for too long can change the resistance of the wire. (8) As the copper sulphate is dangerous I will wash my hands after each experiment. Apparatus: The apparatus that I require in this investigation is: (1) Measuring cylinder- This will be used to measure 150ml of the copper sulphate solution (2) Ammeter- This will be used to se how much current is flowing through the circuit (3) Stop watch- This will be used to time how long the practical will be on for.
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Distance between two electrodes - If the distance between the two electrodes is greater, the copper ions require to travel more from the anode to the cathode. If the distance between the two electrodes is smaller, the copper ions need less energy to flow from the anode to the cathode than when the distance between of the electrodes is far apart. 4). Surface area of electrodes- The surface area of the electrodes affected the number of ions that can be lost or gained at the same time.
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The fourth variable the affects the experiment is the size of the concentration. The higher the concentration, again the positive and negative ions are more active therefore, there are more chances of collisions at the cathode to form more copper. I will be changing the size of the current throughout my experiment. I will use a rheostat and an ammeter to control the size of the current so that it is adjusted accurately. BACKGROUND INFORMATION: British scientist, Michael Faraday (1791-1867)
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The size of the electrodes was also never exactly the same, as they were reused, so the amount of electrolysis differed from experiment to experiment. The separation of the electrodes was a small source of error, as they were not always exactly the same distance apart. The current which was controlled with the rheostat was not always the same, as the amount of copper decreases, so does the resistance, and so the current increases. Other errors could have been caused by the apparatus, such as the ammeter, which is quite old, and may not be perfectly calibrated, and the scales, which only show the mass to 2 decimal places.
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These will tend to stay close because they are attracted to the negative charge on the piece of metal. Some of them will be attracted enough that they will reclaim their electrons and stick back on to the piece of metal. A dynamic equilibrium will be established when the rate at which ions are leaving the surface is exactly equal to the rate at which they are joining it again. At that point there will be a constant negative charge on the magnesium, and a constant number of magnesium ions present in the solution around it. Simplifying the diagram to get rid of the "bites" out of the magnesium, you would be left with a situation like this: Don't forget that this is just a snapshot of a dynamic equilibrium.
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In such instances the alternative half equation is: 2Br- Br� + 2e- Electrolysis - How Does It Happen? A compound made from metal and non-metal has ions which cannot move freely. This means the compound cannot conduct electricity, nor can it move towards electrodes. This is why the electrolyte must be in liquid form - either by melting it or by dissolving it in water.
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Investigate the effect of the amount of sodium chloride, i.e. concentration gradient, in the aqueous solution on the electric current during electrolysis.
By keeping the factors controlled and equal, you can prove it is the concentration. The following factors/variables must be controlled or monitored during the experiment: 1. Temperature 2. Quantity of solution 3. Voltage 4. Size of electrodes 5. Distance between electrodes 6. Surface on the electrodes 7. Distilled water I plan to finish the experiment in one day, so the temperature won't change drastically and use a stop-clock to maintain the time duration for applying voltage to 10s. By using a volumetric flask and pipette, I can measure and control the quantity of solution for each test batch more accurately.
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and which flow throughout the metal. This is what allows electric current to flow so well in all metals. An electrode is a component of an electric circuit that connects the wiring of the circuit to a gas or electrolyte. A compound that conducts in a solution is called an electrolyte. The electrically positive electrode is called the anode and the negative electrode the cathode. When a positive and a negative electrode are placed in a solution containing ions, and an electric potential is applied to the electrodes, the positively charged ions move towards the negative electrode, and the negatively charged ions to the positive electrode.
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With some metals there is no reaction at all. These are the metals at the bottom of the reactivity series, such as gold. Also the most reactive metals form their oxides much quicker than the less reactive metals. This type of reaction is called an oxidation reaction, because the metal gains oxygen. The formula for the reaction with air is: Metal + Oxygen = Metal Oxide Metals can also be placed in water to see how they react. Again the extremely reactive metals potassium and sodium react more vigorously compared to the less reactive metals.
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On reaching the electrodes, the ions may gain or lose electrons and be transformed into neutral atoms or molecules. The copper ions move to the cathode and are discharged by gaining electrons, and are deposited on the electrode as metallic copper, Equation Cu+2 + 2e- ==>Cu (Reduction) The chloride ions move to the anode and are discharged, by losing electrons, as chlorine gas. Equation 2Cl-1==> Cl-1 + 2e- (Oxidation) Here is a diagram to show the ions going to the electrodes Hypothesis I think that in the solution the more electrons flowing the more you have a chance of seeing a better chemical reaction taking place.
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If the metal surface of the cathode is chemically and physically clean, the discharged atoms of copper are deposited within normal inter atomic spacing of the atoms of the basis metal and attempt to become an essential part of it. If the basis metal is copper, the new copper atoms will frequently arrange themselves to continue the structure of the basis metal, the plate becoming more or less indistinguishable from and inseparable from the basis metal. Copper is a chemical element, extremely ductile to metal unusually good conductor of electricity and heat.
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An investigation to find out what factors affect the rate of electrolysis of a solution containing copper (II) ions.
This means that the more voltage flowing through the circuit the faster the reaction will take place. Concentration of a solution: For many reactions involving liquids or gases, increasing the concentration of the reactants increases the rate of reaction. In a few cases, increasing the concentration of one of the reactants may have little effect of the rate so changing the concentration could speed up the reaction or it could have no affect at all. Although, it is very common that when you increase the concentration the reaction does speed up.
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- Electrical energy is expensive, so it depends on the electrical energy source cost. I.e. Hydro electrical power cheaper. Chemical reduction processes usually use carbon or carbon monoxide, made by heating coal, therefore a lot of coal is used in the extraction process. * Any other further processing required after extraction has been carried out, such as the purity requirement - From a mineral, it is easy to produce metals such as iron, which is 95% pure. Should the iron need to be purified further to 99% it would cost a lot more money, and time.
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Outside the core there is a layer of dense liquid rock called magma. This layer of magma is called the mantle. The thin solid layer of rock that makes up the outside of the earth is called the crust. Plate Tectonics The crust is not all one piece but is made up of sections called plates. These plates are floating about on the mantle and moving. At places where the plates are colliding earthquakes and volcanoes occur . Where plates are colliding the more dense plate is forced underneath the less dense plate.
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