Outline the role of the photosynthesis process to explain what is meant by this statement. (3 marks) chlorophyll 6CO2(g) + 6H2O(l) + energy ? C6 H12 O6 (aq) + 6O2(g) 2830 kJ glucose Photosynthesis is the process in which plants use the sun’s light energy to convert carbon dioxide and water into carbohydrates such as glucose, sucrose, starch and cellulose. Carbohydrates are high energy compounds because when they react with oxygen, they produce large amounts of energy.
Plants make their own food by using the glucose they produces as an energy source for growth, reproduction, repairing damaged tissues… Animals cannot carry out photosynthesis, so they eat the plants to obtain food, hence, energy. For that reason the energy for life comes from the sun. 2. Explain what is meant by thermal pollution and discuss the implications for aquatic life. (3 marks) Thermal pollution is a discharge into a river or lake of a lot of hot water which is enough to significantly (2°C to 5°C) increase the temperature of water.
This abnormal increase in temperature is potentially harmful to aquatic organisms in these ways: •Stress to organisms due to less dissolved oxygen. •Increase metabolism which would increase oxygen demand, and this would lead to decreasing oxygen supply. •Fish eggs don’t hatch. •Migration and spawning would be set off at the wrong time due to false temperature cues. •Sudden change in temperature would kill off fish eggs even if the temperature is in the egg’s survival range. 3. Identify the sources of pollution which accompany the combustion of organic compounds and explain how these can be avoided. 6 marks) Carbon dioxide is produced by power plants and motor vehicles by complete combustion when there is plenty of oxygen supply. It is a major pollution of enhanced greenhouse effect. This can be avoided by using filters such as catalytic converters to remove it. C(s) + O2(g) ? CO2(g) 2C8H18(l) + 25O2(g) ? 16CO2 + 18H2O(l) Sulfur dioxide is produced by the combustion of fossil fuels which contributes to form acid rain which leads to: •Increasing acidity of lake and/or river. • Erosion of marble and limestone buildings. •Accelerating the rate of corrosion.
The Term Paper on Energy the Present and Future Scenario
... just carbon-rich plant remains. Pressure and temperature further compressed the material. This aided the process of producing coal as more ... between 1850 and 1970, per capita use of industrial energy increased about twentyfold, and total world use of industrial and ... cell consists of an electrolyte sandwiched between two electrodes. Oxygen passes over one electrode and hydrogen over the other, ...
This can be avoided by lowering combustion temperatures to prevent the formation of sulfur dioxides. S(s) + O2(g) ? SO2(g) 2SO2(g) + O2(g) ? 2SO3(g) SO3(g) + H2O(l) ? H2SO4(aq) Nitrogen oxide is produced in the combustion chamber of petrol or from diesel engines and combustion of coal in power plants. The combustion of nitrogen in fuels occurs at high temperatures. It causes respiratory problems and contributes to form photochemical smog and acid rain like sulfur dioxide. This can be avoided by lowering the combustion temperature to prevent the formation of nitrogen oxides.
N2(g) + O2(g) ? 2NO(g) No(g) + O2(g) ? NO2(g) 2NO(g) + O2(g) ? 2NO2(g) Carbon monoxide or soot is produced by incomplete combustion when there is insufficient oxygen supply. Carbon monoxide is toxic when it combines with haemoglobin in red blood cells in preference to oxygen; this reduces the ability of blood to transport oxygen – suffocation. Soot is carcinogenic. This is can be avoided by ensuring complete combustion. 2C8H18(l) + 17O2(g) ? 16CO(g) + 18H2O(l) OR C8H18(l) + 5O2(g) ? CO(g) +7C(s) + 9H2O(g) Tetraethyl lead (Pb(C2H5)4) is added to petrol to produce leaded petrol.
The leaded emitted to the environment is a toxic metal which can enter the food chain. 4. Explain combustion in terms of slow, spontaneous and explosive reactions and explain the conditions under which these occur. (4 marks) Combustion is a self-sustaining chemical reaction in which a substance reacts with oxygen and release energy, usually in the form of heat and light. Therefore, it is an exothermic reaction. Slow combustion occurs at low temperatures and non-rapid rates. It occurs when we use big lumps of fuel and restrict the supply of air.
The Essay on The Effect of Temperature on Rate of Reaction
In this experiment I shall be investigating how temperature affects the rate of reaction Rates of reaction The Factors that affect the rate of reaction are temperature, surface area, concentration, catalysts, light and pressure Surface area – Surface area is the amount of solid surface that is available for reaction – Only affects solids so this will not affect our experiment – When ...
For example: respiration; fuel is burnt at low ignition temperature (body temperature) and produces carbon dioxide, water and energy. Spontaneous combustion occurs when a substance doesn’t require the application of external energy in order to combust. It occurs when small particles of coal or gaseous fuel are sprayed into excess air. For example: the exposure of white phosphorus forms an oxide because the heat from this reaction is enough to ignite the rest of the phosphorus. Explosive combustion is an uncontrolled chemical reaction that occurs at a very fast rate in which heat is released.
Explosions occur when there are high concentrations of gases or finely divided solid particles of materials (as the surface area is increased) in excess heated air. For example: cylinders of petrol and diesel engines in vehicles. 5. Describe the role of catalysts in chemical reactions, using a named industrial catalyst as an example. (2 marks) A catalyst is a substance which increases the rate of chemical reaction by providing an alternative pathway with lower activation energy without itself being consumed or permanently changed.
Palladium or nickel catalyst is used in the margarine industry in the process of hydrogenation of unsaturated fats to saturated fats. Hydrogen molecules and unsaturated hydrocarbon molecules are absorbed onto the surface of the catalyst and the bonds between the hydrogen atoms break as new metal-hydrocarbon molecules form. The absorbed atoms migrate to the metal surface and react; the materials convert from an absorbed state to form products. 6. Explain the relationship of ignition temperature and activation energy. (2 marks) Ignition temperature is the minimum temperature required for the gas or mixture to spontaneously combust.
Activation energy is the minimum amount of energy reactant molecules must possess in order to form products. The greater the activation energy, the higher is the ignition temperature. 7. Milk kept at room temperature can sour in as little as a day, but can be kept in a refrigerator. Use energy profile and molecular kinetic energy distribution diagrams to explain these observations. (4 marks) The temperature is the measure of the average kinetic energy of the reacting particles. The increase in temperature also changes the distribution of molecular kinetic energies.
The Term Paper on Active Site Rennin Reaction Molecule
Information on enzymes & rennin Enzymes are biological catalysts that speed up reactions without being affected so that they can be used to speed up another reaction. Enzymes are soluble globular proteins. Enzymes reduce the energy needed to make a reaction happen. This energy is known as the "activation energy." We need enzymes to stay alive, without them, the reactions in our body would take ...
Not all reactant particles have the same kinetic energy at the same temperature. At a higher temperature, there are greater proportions of molecules that have kinetic energy more than activation energy. Therefore, increasing temperature will result in greater number of reactant molecules with kinetic energy greater than the required activation energy, which results in more successful collisions. The souring of milk is a chemical reaction, so the rate of chemical reaction increases with heat. As the heat increases, the average kinetic energy also increases, meaning that particles collide more often and thus react more often. . (6 marks) a)Explain why the flash point for pentane (- 49°C) is much lower than its ignition temperature (260°C).
Flash point is the minimum temperature for a liquid fuel to produce sufficient vapour for a spontaneous combustion to occur in the presence of a small flame. Flash point is the temperature where a product develops vapours. A product will not ignite until it reaches its ignition temperature (the temperature in which it can spontaneously combust and continue to burn without any addition of heat), consequently, flash point (especially for hydrocarbons) is significantly lower than the ignition temperature. )
Account for the explosive risks in small motor boats, wheat storage silos and underground coal mines. The flashpoint of a product determines the safety precautions needed for handling and storing the fuel. An explosive reaction occurs when fuel molecules (molecules that can burn, including: wheat and coal particles and petrol vapour) are well mixed with the air and there is no limit on the flow of fuel to the combustion area in a small boat, mine or silo. When there is a fine mixture with the right oncentrations and a spark or ignition appears, this spark begins a reaction that accelerates so quick that the heat release and gas pressure creates an explosion. Therefore, in small and or confined spaces e. g. the silo, there is a possibility of explosive risks because the wheat particles cannot move out and so remain mixing with the air if there is no ventilation. This goes same for petrol vapour in small motor boats and coal particles in underground coal mines. c) Explain how white phosphorus, which has much lower ignition temperature than butane, can have a lower risk of explosive combustion.
The Term Paper on Formal Report – Kinetics Of Reaction: The Iodine Clock Reaction
In everyday life, several reactions are encountered, but still knowledge on how fast these occur and the factors affecting it were still insufficient. This study aimed to determine the different factors affecting the rate of reaction and how these factors affected it. An experiment named iodine clock reaction was done to answer the questions raised. In this study the reaction of iodide ion and ...
As explained in parts (4 & 8b), an explosive combustion would need a mixture of fuel and air and the addition of a spark or ignition. Assuming white phosphorus to be solid, it would not mix with air as successfully as butane as a gas, thus, an explosive reaction or a high-risk explosion would not take place, in spite of the ignition temperature of white phosphorus and butane.
