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30 Cards in this Set
- Front
- Back
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What type of oil is vaporised for fractional distillation? |
crude oil |
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Why is crude oil used for fractional distillation? |
Crude oil contains a huge number of hydrocarbons with molecules of different sizes, a mixture of gases, liquids and solids. Fractional distillation is a method of separating these hydrocarbons based on the different boiling and condensing temperatures. |
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How does the temperature change as you go up the distillation column? |
Decreases |
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What is the average range of temperatures in a fractional distillation column? |
About 300 degrees to 85 degrees |
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Why do long chains such as tar leave the bottom of the fractional distillation column? |
Long chains (around 20+ carbons long) have very strong intermolecular attractions so they require a lot of energy to change state, this means they will have very high boiling points (higher then hottest temp of column) so they will instantly become solids and leave bottom of column. |
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Why do short chains? such as refinery gas leave the top of the fractional distillation column? |
Short chains have weak intermolecular attractions so require little energy to change state this means they will have low boiling points so they will remain as gasses throughout the column. |
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What happens to medium sized carbon chains such as diesel, kerosene, naphtha and petrol in a fractional distillation column? |
These chains have varying boiling & condensing points. longer chains, higher boiling points, condense on brackets towards bottom & drip off to sides, whereas shorter chains, lower boiling points, condense further up, this successfully separates different types of molecules based on their size. |
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What is cracking? |
The breaking of carbon double bonds by using a catalyst or subjecting them to high temperatures. E.g butane can be broken into ethane and ethene |
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What are the products of fractional distillation? (in order from bottom to top) |
Tar, diesel, kerosene, naphtha, petrol and refinery gas. |
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ery gas.Describe the process of fractional distillation |
Crude oil is heated above temp of hydrocarbons so they vaporise & are released into a column. Due to decreasing temp, different sized hydrocarbons will condense at different places, (larger molecules at bottom, smaller molecules at top), causing separation. |
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What is tar used for? |
Sealing roads |
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What is needed for cracking to occur? |
Catalyst paired with high temperatures or Catalyst with pressure applied to molecules with carbon double bonds. |
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What are the two processes used to obtain smaller useful hydrocarbons? |
Cracking and fractional distillation |
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What are hydrocarbons? |
Compounds only made up of hydrogen and carbon. |
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What is the differences and similarities between the boiling points of ethane, ethene and ethanol? |
Ethane and ethene both have very low boiling points (in the negatives) whereas ethanol, although a small molecule, has a very high boiling point (around 60 degrees) |
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What are the first 8 alkanes? |
Methane, Ethane, Propane, Butane, Pentane, Hexane, Heptane, Octane |
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What are the first 7 alkenes? |
Ethene, Propene, Butene, Pentene, Hexene, Heptene, Octene |
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Why do the states of molecules change as their size increases? |
Because as molecules increase in mass, more energy is required to over come intermolecular attractions between molecules. So at room temp, the smallest alkanes are gases, larger are liquids and largest are solids |
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What does it mean when you say that alkenes are 'unsaturated?' |
Alkenes are said to be unsaturated because one of the bonds in the carbon-carbon double bond can be broken and new atoms can be added to the molecule. Once this occurs and the new molecule contains only single bonds, it is said to be saturated. |
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What is polymerisation? |
When one of the bonds in the carbon-carbon double bond of an alkene breaks and other alkene molecules can then join to two new available bonds. |
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What do multiple Propene molecules form during polymerisation? |
Polypropene |
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What are the solubility rules for alkanes, alkenes and alcohols in water? |
- Alkanes and alkenes are insoluble in water- Alcohols are soluble in water |
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What are the possible products of incomplete combustion? |
Either; Carbon monoxide + wateror; Carbon (in the form of soot) +water |
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What is complete combustion and what is the equation involving methane? |
When all carbon and hydrogen atoms have reacted with oxygen atoms.Methane + oxygen ---> Carbon dioxide + water |
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What are the negative effects of incomplete combustion on both people and the environment? |
CARBON MONOXIDE attaches to haemoglobin (in blood) in the place of oxygen so that you die of oxygen starvation. CARBON coats leaves with soot so that photosynthesis can't occur. Pure carbon, when inhaled by humans can also cause asthma and lung cancer. |
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What is needed for fermintation |
- Temp between 20 - 45 degrees- Anaerobic conditions (no oxygen present)- Yeast (acts as a catalyst) |
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What is the word and symbol equation for fermentation? |
Glucose + Water ----> ethanol + carbon dioxide 2CH12O6 + H20 -----> 2C2H5OH + 2CO2 |
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What can polyethene be used for? |
Plastic bags, glad wrap, water pipes, wire and cable insulation. because it is Flexible/malleable, strong, chemically inert, can be transparent. |
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What can polypropene be used for? |
Rope, chairs, textiles, reusable containers, plastic hinges because it Is Flexible, tough, lightweight, chemically inert, heat resistant. |
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effects of carbon dioxide (complete combustion) |
CO2 - Car emissions, respiration (overpopulation, farming) Greenhouse gasses such as CO2 and methane in the atmosphere retain heat which leads to the increase of earths average temperature (global warming) |
