Flashcards in GCSE chemistry crude oils Deck (44)
what is a compound?
A compound is two or more different types of atom that are chemically bonded.
what is a mixture?
A mixture is made from different substances that are not chemically bonded.
what do you call a substance made from only one type of atom?
what is a hydrocarbon and what does it make?
A hydrocarbon is a compound made of only hydrogen and carbon covalently bonded together. Many different chain lengths of hydrocarbons make crude oil. They can be separated for different uses.
how does crude oil form?
naturally over millions of years from the remains of living things.
what is an Alkane?
They are carbons and hydrogen bonded by only single bonds. They are referred to as saturated compounds because they have as many hydrogens as possible.
how many bonds do a) carbon and b) hydrogen have in an Alkane.
what makes Alkanes unreactive?
Because they have singles bonds and are saturated.
are the hydrocarbon molecules chemically bonded together?
No. This means they keep their original properties such as condensing points.
how can you split the different groups of hydrocarbon?
by using fractional distillation (a physical method, because the molecules are not chemically bonded) . The fractionising column works continuously: heating crud oil, and the vapour rising an condensing in different fractions depending on the length of chain.
what is distillation?
Distillation is a process that can be used to separate a pure liquid from a mixture of liquids. It works when the liquids have different boiling points. Distillation is commonly used to separate ethanol (the alcohol in alcoholic drinks) from water
what is boiling point? an how does increasing the chain length of a hydrocarbon change it?
The temperature at which a liquid turns into a gas. Increasing the chain length leads to higher boiling points bigger the chain has a bigger surface area and therefore more intermolecular forces holding them together.
what is volatility? an how does increasing the chain length of a hydrocarbon change it?
How easily a substance turns into a gas. Because a longer chain length means a higher boiling point the higher the volatility will be: more energy is needed to break more intermolecular forces.
what is viscosity? an how does increasing the chain length of a hydrocarbon change it?
The texture of the liquid/ how runny it is. increased chain lengths lead to increased viscosity because the bigger surface area means there are more intermolecular forces and it is held together more, meaning it will not move about as easily.
what is flammability? an how does increasing the chain length of a hydrocarbon change it?
How easily a substance catchs fire. increased chain length leads to reduced flammability because more energy is needed to break the bigger intermolecular forces and therefore it needs a lot more energy to catch fire.
what is the general formula of an alkane?
what is a display formula?
In a displayed formula, the symbols for each atom are joined by straight lines. Each line represents a covalent bond (a shared pair of electrons).
what is a molecular/ chemical formula?
The chemical formula of a compound tells you how many atoms of each element the molecule contains e.g. O2
give a use for a very viscous hydrocarbon.
lubricating engine parts and covering roads.
give a use for a hydrocarbon with longish chain, quite low boiling point, quite easily ignited and not very viscous.
pertol: its a liquid which is ideal for storing in a fuel tank and it can flow to the engine where its easily vapourised before its ignited.
give a use for a hydrocarbon with very short molecules.
refinery gas is good for bottled gas. it has low boiling point and is stored under pressure before its ignited.
do crude oils burn cleanly?
yes, this is what makes them good fuels.
why are alternatives (wind, nuclear, solar, ethanol) for crude oil being used?
because it costs a lot of money to take oil out of the ground and it is not renewable. However thing generally are set up to use oil. e.g. cars are designed for petrol or diesel and its available, this makes it they easiest and cheapest thing to use.
as well as crude oil being cheap and easy why do we use it more than other resources?
its more reliable. wind and solar won't work without the correct weather conditions and nuclear has health concerns.
what is bad about changing fuels?
- it will take time to develop new fuels.
- it will take time to adapt things so that different fuels can be used on a wider scale. e.g different car engines.
why is crude oil not good for the environment?
- oil spills can poison animals
- when burnt it releases gases which can ause global warming, acid rain and global dimming.
what do car produce when petrol burns?
sulphur dioxide (if the fuel contains inpurities) , nitrogen oxides and carbon dioxide.
write a word equation to show a hydrocarbon getting combusted. its is oxidised and produces heat as well.
hydrocarbon + oxygen = carbon dioxide + water vapour
what is released if incomplete combustion occurs?
solid particles (soot & unburnt fuel) and carbon monoxide.