C7 Organic chemistry Flashcards Preview

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Flashcards in C7 Organic chemistry Deck (39)
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What is crude oil made from ?

Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried

in mud.


Crude oil is finite, what does finite mean ?

Finite means that when it is used up it takes millions of years to be replaced.


What is a hydrocarbon ?

A compound made from hydrogen and Carbon only.


What is the general formula of an alkane.

The general formula for the homologous series of alkanes

is CnH2n+2


Draw the displayed formula for methane.

See diagram


What is the formula for butane



What are the names of the 1st 4 alkanes ?

methane, ethane, propane and butane.


The many hydrocarbons in crude oil may be separated into fractions, by which process ? 

Fractional distillation


The many hydrocarbons in crude oil may be separated into fractions,  what do the fractions have in common ?.

Each  fraction contains molecules with a similar number of carbon atoms,


What  useful materials can the fractions be processed into ?

The fractions can be processed to produce fuels and feedstock for the petrochemical industry.


Name 4 fuels which can be produced from crude oil ?

Many of the fuels on which we depend for our modern lifestyle, such as petrol, diesel oil, kerosene, heavy fuel oil and liquefied

petroleum gases, are produced from crude oil.


Explain how fractional distillation works

in terms of evaporation and condensation.

The crudeoil gets heated till the boiling point of the 1st fraction is reached. The temperature remains constant until that fraction has evaporated. The fraction once evaporated comes off as a gas and is then cooled down ( condensed) and collected as a liquid. This process continues until all the fractions have been collected.


What is it about a hydrocarbon that affects it's boiling point ?

The chain length


How is energy released from fuels ?

The combustion of hydrocarbon fuels releases energy.


What are the products of combustion ?

 During combustion, the carbon and hydrogen in the fuels are oxidised. The complete combustion of a hydrocarbon produces carbon dioxide

and water.




How does the boiling points , viscosity and m flammability of alkanes change as the chainlength increases ?


Boiling point, and viscosity  increases as we increase the chainlength. The flammability decreases as we increase the chain length of the alkanes.


Whay are alkanes cracked ?

Hydrocarbons can be broken down (cracked) to produce smaller, more useful molecules.


What are 2 methods used for cracking alkanes ?

Cracking can be done by various methods including catalytic cracking and steam cracking.


What are the products of cracking alkanes ?

The products of cracking include alkanes and another type of hydrocarbon called alkenes.


What is the test for an alkene ?

Alkenes are more reactive than alkanes and react with bromine water, which is used as a test for alkenes.


When  Bromine water is added to alkenes what observations  are made.

The bromine water changes from orange to colourless.


What are used to make Polymers ?

Alkenes are used to produce polymers and as starting materials for the production of many other chemicals.


Write an equation for the cracking of C16H34

Any answer is correct as long as smaller alkanes are made and alkenes are in the product. The number of carbons and hydrogens must be the same on both sides of the equation.


Higher tier

What is the general formuila for an alkene ?

Alkenes are hydrocarbons with a double carbon-carbon bond. The general formula for the homologous series of alkenes is CnH2n


Higher tier only

What is an unsaturated molecule ?

Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon



Higher tier only

What are the first 4 members of alkenes ?

The first four members of the homologous series of alkenes are ethene, propene, butene and pentene.


Chemistry only

What is the functional group of an alkene

Alkenes are hydrocarbons with the functional group C=C.


In what way are alkenes similar and different to alkanes in their reactions with oxygen ?

Alkenes react with oxygen in combustion reactions in the same way as other hydrocarbons, but they tend to burn in air with smoky flames because of incomplete combustion.


Chemistry tier

What happens when alkenes react with hydrogen ?

They make alkenes


Chemistry tier


What happens when alkenes react with hydrogen halides ?

They make halogenoalkanes.