them paper 2
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285 questions
| 🇬🇧 | 🇬🇧 |
| Where is crude oil found and how is it formed | Found in rocks, formed over millions of years from plankton remains found in mud |
| What is crude oil made up of | Hydrocarbons |
| What is a hydrocarbon | Molecules made up of hydrogen and carbon atoms only |
| General formula for alkanes | Cn+H2n+2 |
| Why are alkanes known as saturated molecules | Their carbon atoms are fully bonded to hydrogen atoms |
| Name the alkane | Methane |
| Name the alkane | Ethane |
| Name the alkane | Propane |
| Name the alkane | Butane |
| What happens to viscosity as the size of hydrocarbon molecules increase | Viscosity increases, long chain hydrocarbons are extremely viscous and flow slower |
| What happens to flammability as the size of hydrocarbon molecules increase | Flammability decreases, short chain hydrocarbons are very flammable |
| What happens to boiling point as the size of hydrocarbon molecules increase | The boiling point increases, short chain hydrocarbons have very low boiling points due to weaker intermolecular forces |
| What happens when hydrocarbon fuels are combusted | They release energy |
| Explain the combustion of hydrocarbons | Carbon and hydrogen atoms in the fuel react with oxygen and become oxidised, if oxygen is unlimited, it produces CO2 and water, called complete combustion |
| Balance the combustion reaction of ethane: C2H6 + O2 --> CO2 + H2O | 2C2H6, 7O2, 4CO2, 6H2O |
| Balance the combustion reaction of butane: C4H10 + O2 --> CO2 + H2O | 2C4H10, 13O2, 8CO2, 10H2O |
| Describe the stages of fractional distillation of crude oil | - crude oil is heated to a very high temp so it boils and all hydrocarbons evaporate and turn into a gas - crude oil vapour is fed into the fractional distillation column which is hotter at the bottom (350) and cooler at the top (25) - hydrocarbon vapours rise up the column + condense when they reach their boiling point - liquid fractions are removed and remaining hydrocarbons continue to rise up the column until they reach their boiling point and condense |
| Where are long chain hydrocarbons removed and why | At the bottom as they have very high boiling points |
| Where are short chain hydrocarbons removed and why | At the top as gases as they have very low boiling points and do not condense |
| Can can some fractions be used for | Fuels and feedstock |
| What is a feedstock | A chemical used to make other chemicals |
| Give examples of fuels that can be made | Petrol, diesel, kerosene, heavy fuel oil, liquified petroleum gas |
| Give examples of feedstock that can be made | Solvants, lubricants, detergents, polymers |
| What is the temp around at the top of the column | 25 degrees celsius |
| What is the temp around at the bottom of the column | 350 degrees celsius |
| Why can't alkenes be used as fuels | Incomplete combustion, they can't release energy |
| Alkenes have at least one what | Covalent carbon to carbon double bond |
| Name the alkene | Ethene |
| Name the alkene | Propene |
| Name the alkene | Butene |
| Why does methene not exist | Methane only contains one carbon atom whilst alkenes need to have a double bond between two carbon atoms |
| Why are alkenes unsaturated | They have two less hydrogen atoms than the alkane with the same number of carbon atoms |
| What's the alkenes functional group | The carbon to carbon double bond |
| What is a functional group | The part of the molecule that determines how it reacts |
| Molecules that all have the same functional group are known as | A homologous series |
| What is produced during the combustion of alkenes and what is the process called | Carbon monoxide, co2, water and unburnt carbon particles, incomplete combustion |
| Why can't alkenes be used as fuels | Incomplete combustion, they can't release energy |
| Why can't alkenes be used as fuels | Incomplete combustion, they can't release energy |
| What are the conditions for a hydrogenation reaction to take place | Temp of 150, nickel catalyst |
| What is a hydrogenation reaction | Alkene + hydrogen --> alkane |
| What are the conditions for a hydration reaction to take place | Water must be in the form of steam, temp of 300, phosphoric acid catalyst, 70 atm |
| What is a hydration reaction | Alkene + steam --> alcohol |
| How would you increase the yield of alcohol in a hydration reaction | The reaction is reversible so unreacted alkenes and steam are passed back through the phosphoric acid catalyst |
| What is a halogenation reaction | Alkene + halogen --> di(halogen)(alkane) |
| Ethene + bromine --> | Dibromoethane |
| Ethene + iodine --> | Diiodoethane |
| Dichloropropane --> | Propene + chlorine |
| What reaction is this an example of | Hydration reaction |
| What reaction is this an example of | Hydrogenation reaction |
| Advantages and disadvantages of producing ethanol with the hydration of ethene | A- yield of ethanol is high D- requires a high temp (lots of energy), ethene comes from crude oil which is finite |
| How else can ethanol be made | Fermentation |
| Equation for fermentation | Symbol: C6H12O6(aq) --> 2C2H5OH(aq) + 2CO2(g) |
| Advantages and disadvantages of producing ethanol with fermentation | A- low temp (less energy), sugar comes from plants and is renewable D- product is an aqueous solution of ethanol and has to be purified by distillation which requires energy |
| Conditions for fermentation | Yeast as a catalyst, 30degrees celsius, must take place in anaerobic conditions, in a slightly acidic solution |
| General formula for alcohols | Cn + H2n+1 OH |
| Alcohols combustion: | Alcohol + oxygen --> carbon dioxide + water |
| What do alcohols form when dissolved in water | Neutral solutions |
| What happens to alcohol when the number of carbon atoms increase | Solubility decreases |
| Alcohols reaction with sodium: | Alcohol + sodium --> sodium alkoxide + hydrogen |
| Symbol and word equation for the reaction of methanol, ethanol, propanol and butanol with sodium | Symbols: CH3OH + Na --> CH3ONa +H2 C2H5OH + Na --> C2H5ONa + H2 C3H7OH + Na --> C3H7ONa + H2 C4H9OH + Na --> C4H9ONa + H2 |
| What does reacting alcohol with an oxidising agent produce | A carboxylic acid and water |
| Give an example of an oxidising agent that could be used | Acidified potassium dichromate |
| What happens when sodium alkoxides dissolve in water | They form strongly alkaline solutions |
| Alcohols combustion: | Alcohol + oxygen --> carbon dioxide + water |
| Why are carboxylic acids known as weak acids | They don't fully ionise/ only partially ionise in aqueous solutions |
| What do you get when you react a carboxylic acid with an alcohol | An ester and water |
| What type of reaction is carboxylic acids and alcohol | A reversible reaction |
| Name three features of the structure of DNA | Consists of two polymer chains made from monomers called nucleotides, there's bases, a double helix structure |
| State the percentages of the earths present atmosphere | 78% nitrogen 21% oxygen 1% argon 0.4% other gases like CO2 |
| Why can't scientists be certain of the worlds early atmosphere | The earth is around 4600 million years old so scientists cannot be certain about the early atmosphere |
| What did the earths early atmosphere mainly consist of | Carbon dioxide with little to no traces of oxygen |
| How was water vapour, nitrogen and CO2 introduced in the early atmosphere | Intense volcanic activity released these gasses |
| How were oceans first formed | The earth started to cool down and water vapour condensed to form oceans |
| What happened to CO2 levels as oceans were formed | It had decreased as CO2 dissolved in the oceans forming a weak acid which reacted with minerals in the sea to form precipitate which over time formed sediments of carbonate rock on the sea bed |
| What was the CO2 in the ocean used to make | Corals, shells of organisms like mussels |
| How did O2 start to get introduced into the atmosphere | Around 2.7b years ago, photosynthetic algae first evolved and produced oxygen |
| When could animals finally start to evolve | When oxygen levels reached a point where they could respire |
| How were the CO2 levels in the early atmosphere decreased | Fossil fuel formation, dissolved in oceans, photosynthesis |
| Explain how coal is formed | -remains of ferns and trees -plant remains covered with sediment rock and compressed -hight temp and pressure created coal |
| Why do the plants used to make coal not decompose when dead | Due to a lack of oxygen or acidic conditions that would allow bacteria to decompose the plants |
| How is crude oil formed | -plankton that have died -settle in mud and compressed by sediment -heat and pressure turn them into crude oil |
| Name a natural gas | Methane |
| Where are natural gases usually found | Oil deposits |
| Similarity of the formation of crude oil and natural gas | Both made from dead plankton |