organic chem

Question 1

what is crude oil?

Answer 1

a finite fossil fuel made from buried plankton which has decomposed under mud for millions of years

Question 2

what is a hydrocarbon?

Answer 2

a substance which is only made of hydrogen and carbon- has the formula C(n) H(2n+2)

Question 3

what is pure crude oil made of?

Answer 3

it is made of lots of hydrocarbons and some impurities eg sulfur

Question 4

why is crude oil by itself not useful?

Answer 4

contains a huge range of lengths of hydrocarbons so it is not useful without being broken down

Question 5

what process splits crude oil into hydrocarbons?

Answer 5

fractional distillation

Question 6

what happens in a fractionating column?

Answer 6

it is heated- hottest at the bottom and cooler at the top. the vapours rise and condense when they are cool enough. short chain hydrocarbons leave at the top and long chains are found at the bottom.

Question 7

what is an alkene?

Answer 7

a hydrocarbon that has a C=C double bond

Question 8

what is a double covalent bond?

Answer 8

a bond in which 2 atoms share 2 pairs of electrons

Question 9

what is the general formula for the alkenes?

Answer 9

C(n) H(2n)

Question 10

what is a saturated hydrocarbon?

Answer 10

a hydrocarbon in which all the bonds between carbon atoms are single bonds

Question 11

describe the trend in boiling point

Answer 11

the longer the hydrocarbon, the higher its boiling point (longer chain- more IMF, harder to break)

Question 12

describe the trend in viscosity

Answer 12

the longer the hydrocarbon, the more viscous it is (longer chain- more IMF, harder to move easily)

Question 13

describe the trend in flammability

Answer 13

the shorter the hydrocarbon, the more flammable (shorter chain- less IMF, easier to break)

Question 14

what is the difference between complete and incomplete combustion?

Answer 14

complete combustion (when there is enough oxygen) produces carbon dioxide and water
incomplete combustion does not use enough oxygen and produces water, carbon particulates and carbon monoxide.

Question 15

what is cracking?

Answer 15

the breaking apart long hydrocarbons into shorter more useful hydrocarbons

Question 16

why is cracking useful?

Answer 16

short chain hydrocarbons are more useful as fuels and release energy so they are more in demand

Question 17

what are the two methods of cracking?

Answer 17

catalytic and steam

Question 18

how is catalytic cracking done?

Answer 18

hydrocarbon is vaporised, gas is passed over a hot catalyst (zeolite which contains aluminium oxide and silicon oxide) and separates into a smaller alkane and an alkene.

Question 19

how is steam cracking done?

Answer 19

hydrocarbon is vaporised, gas is passed over steam at around 800 degrees and separates into a smaller alkane and an alkene.

Question 20

what is the test for alkenes?

Answer 20

it turns bromine water from orange to colourless

Question 21

what are alkenes useful for?

Answer 21

making polymers and other chemicals

Question 22

what is a monomer?

Answer 22

a small molecule that can join together with other small molecules to form polymers

Question 23

what happens to the bond in alkenes when it forms a polymer?

Answer 23

the C=C bond turns into a single bond and the unit repeats