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GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of.

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Presentation on theme: "GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of."— Presentation transcript:

1 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Keywords: Fractionating column, fractions Prior Learning: Know what a hydrocarbon & alkane is.

2 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Learning Objectives: Identify and explain That crude oil is separated using fractional distillation. The properties of each fraction and how they relate to chain length. Which fractions make useful fuels and why. I will be successful in this lesson if I can: (Level C) State that crude oil is separated into fractions by fractional distillation. List how the properties change from small chain fractions to long chain fractions. State which fractions are useful fuels. (Level A) Explain the key steps involved in fractional distillation. Relate the trend in properties to molecular size.

3 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column What fuels have you used already today? Transport Petrol Diesel Gas Heating Oil Gas Cooking Gas Charcoal Lighting Gas Oil Even electricity is likely to have been produced by fossil fuels

4 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Consider this diagram & these keywords SEPARATE MIXTURE BOIL HEAT MIXTURE HEAT BOIL SEPARATE

5 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Fractional Distillation What is it??? LfbUPc&feature=player_embedded LfbUPc&feature=player_embedded 1.Where is crude oil formed and how is it extracted? 2.What is crude oil? 3.What are the simple state changes used in this distillation? 4.What property of the crude oil fractions cause them to separate in the fractionating column?

6 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Fractional Distillation 1.Produced deep in the earth from the long term heat and pressure of animal and plant remains. It is either pumped to the surface or rises due to its own pressure. 2.Crude oil is a mixture of many hydrocarbons. 3.Condensation (gas to liquid) and evaporation (liquid to gas). 4.Boiling point will separate the fractions. The lighter fractions (less smaller carbon chains – smaller molecules, lighter in colour) have a lower boiling point and so will move up the fractionating column. Inside the column there are many trays with holes to let gases through. Vapours move up the column & condense on the trays when they reach their bp. Fractions with low bp burn more easily which makes them useful as fuels. What would you expect to collect from the top of the column?

7 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Fractional Distillation Demonstration 1.Soak mineral wool in crude oil and place in a boiling tube. 2. Fix the thermometer bung & side arm. 3. Gently heat the boiling tube. when the temperature stabilises at about 80 o C then 1 type of fraction is separated. 4. Change the collecting tube as the temperature rises again. 5. Repeat step 4 four times collecting five fractions & leaving the residue in the boiling tube. 6. Tip each fraction onto mineral wool & ignite.

8 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Fractional Distillation Once fractions are collected, they need more refining before they can be used.

9 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Read p56 of text

10 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column

11 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Over 85% of crude oil is used as a fuel for heating and transport. Only 8% is used to make plastics and other chemicals. A fuel is a substance that reacts with oxygen to produce useful energy. A large amount of oil is used as fuel because the hydrocarbons in the fractions burn easily and produce a large amount of useful energy.

12 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Liquid petroleum gas (LPG) contains propane and butane. They are stored under pressure in metal cylinders. LPG is used for heating and cooking, especially where piped gas cannot be used, such as camp sites and boats.

13 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Gasoline is one of the most important fractions because it is used as a fuel for cars. The gasoline fraction must be refined before it can be used in cars as petrol. Impurities are removed, and chemicals are added to ensure the engine runs smoothly. In the past, these chemicals were lead compounds but because of lead’s harmful effect on health and the environment, they have been replaced by safer compounds.

14 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Naphtha is a very important fraction that has many uses. For example, it is: added to petrol and other fuels. a raw material (feedstock) in the production of chemicals and plastics used as a cleaning fluid and industrial solvent (a substance that can dissolve another substance)

15 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Kerosene, also called paraffin, is mainly used as aviation fuel for jet aircraft. It is also used in central heating systems, lamps and stoves. Diesel is mainly used as a fuel for lorries, buses and cars, and in some boats.

16 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Lubricating oil, as its name suggests, is used as a lubricant in products with moving parts, such as engines. Fuel oil is a heavy fraction used as a fuel for large industrial boilers, oil-fired power stations and ships.

17 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Residue contains paraffin waxes and bitumen, the heaviest product to come from an oil refinery. Paraffin waxes (not the same as paraffin/kerosene) are used in candles and waterproofing. Bitumen is used in road construction and waterproof roof material.

18 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column

19 GCSE Core Chemistry Exam tip; You MUST be able to explain how fractional distillation works. Small molecules (compounds with low bp) are at the top of the fractionating column Learning Objectives: Identify and explain That crude oil is separated using fractional distillation. The properties of each fraction and how they relate to chain length. Which fractions make useful fuels and why. I will be successful in this lesson if I can: (Level C) State that crude oil is separated into fractions by fractional distillation. List how the properties change from small chain fractions to long chain fractions. State which fractions are useful fuels. (Level A) Explain the key steps involved in fractional distillation. Relate the trend in properties to molecular size.


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