This branch of chemistry gets its name from the fact that the main sources of organic compounds are living, or once-living materials from plants and animals. Revision Notes Word-fill quiz 7. This process is called fractional distillation. Alkane molecules can be represented in the following forms: C 2H 6 or You should be able to recognise substances as alkanes given their formulae in these forms. Exam revision summaries and references to science course specifications are unofficial. Revision Notes Revision Notes Revision Notes 9. Knowledge of trends in properties of hydrocarbons is limited to: boiling points, viscosity and flammability.
Alkenes are used to produce polymers and as starting materials for the production of many other chemicals. . Other products cannot be reused and so are recycled for a different use. You should be able to identify formulations given appropriate information but you do not need to know the names of components in proprietary products. You should be able to : describe the main changes in the atmosphere over time and some of the likely causes of these changes, and describe and explain the formation of deposits of limestone, coal, crude oil and natural gas.
If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change. Revision Notes Revision Notes 6. The gases released into the atmosphere when a fuel is burned may include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. In everyday language, a pure substance can mean a substance that has had nothing added to it, so it is unadulterated and in its natural state, eg pure milk. Many products are complex mixtures in which each chemical has a particular purpose. Sterilising agents used for potable water include chlorine, ozone or ultraviolet light. Carbon monoxide and soot carbon particles are produced by incomplete combustion.
You should be able to interpret appropriate given data to predict the effect of a change in temperature on given reactions at equilibrium. These sources include fossil fuels which are a major source of feedstock for the petrochemical industry. The remains of plankton were deposited in muds on the sea floor and were covered over and compressed over millions of years, producing crude oil and natural gas that became trapped in the rocks. Potable water is not pure water in the chemical sense because it contains dissolved substances. Chemists also aim to develop ways of disposing of products at the end of their useful life in ways that ensure that materials and stored energy are utilised. Required practical 5: You should have investigated how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity 'cloudiness'! Bioleaching uses bacteria to produce leachate solutions that contain metal compounds. Energy, water, resource consumption and production of some wastes can be fairly easily quantified.
You do not need to know the names of specific alkanes other than methane, ethane, propane and butane. Separation depends on the distribution of substances between the phases. The plants are harvested and then burned to produce ash that contains the metal compounds. Water that is safe to drink is called potable water. You should be able to describe in general terms the conditions used for catalytic cracking and steam cracking. Different reactions need different catalysts. You should be able to balance chemical equations as examples of cracking given the formulae of the reactants and products.
The vast array of natural and synthetic carbon compounds occur due to the ability of carbon atoms to form families of similar compounds. Natural resources, supplemented by agriculture, provide food, timber, clothing and fuels. You should be able to comment on the relative ease of obtaining potable water from waste, ground and salt water. The products of cracking include alkanes and another type of hydrocarbon called alkenes. The tests are based on reactions that produce a gas with distinctive properties, or a colour change or an insoluble solid that appears as a precipitate. Appreciate that problems of reducing the carbon footprint include eg scientific disagreement over causes and consequences of global climate change, lack of public information and education, lifestyle changes, economic considerations, incomplete international cooperation.
Sulfur dioxide is produced by oxidation of sulfur in the fuel. The minimum amount of energy that particles must have to react is called the activation energy. Many useful materials on which modern life depends are produced by the petrochemical industry, such as solvents, lubricants, polymers, detergents. Plot two variables from experimental or other data. Catalysts increase the rate of reaction by providing a different pathway for the reaction that has a lower activation energy. Test for oxygen The test for oxygen uses a glowing splint inserted into a test tube of the gas.
You should be able to write balanced equations for the complete combustion of hydrocarbons with a given formula. Cracking can be done by various methods including catalytic cracking and steam cracking. Know how to draw a reaction profile for a catalysed reaction. The causes of these changes are sometimes man-made and sometimes part of many natural cycles. The compounds in a mixture may separate into different spots depending on the solvent but a pure compound will produce a single spot in all solvents. We support all students from those who want to understand the basics, through to those who want to follow a career in science or follow a higher education science course. In the context of chromatography, be able to: recognise and use expressions in decimal form, use ratios, fractions and percentages, make estimates of the results of simple calculations, use an appropriate number of significant figures.