Chemistry 7 (paper2)

define hydrocarbon

compounds of hydrogen and carbons

what are the first 4 simple hydrocarbons?

methane

ethane

propane

butane

define homologous series

when compounds all have similar properties and react in a similar way

what is the general formula for alkanes?

CnH2n+2

what are the 6 features of alkanes?

saturated

boiling point increases with chain length

alkanes with more than 4 carbons are liquid at room temperature

shorter alkanes are more volatile

long alkanes are viscous

shorter alkanes are flammable

define saturated

every carbon has 4 single covalent bond

define volatile

evapourate easier

define viscous

thick and sticky

what are the main uses of combustion reactions?

fuel

what is the equation for complete combustion

hydrocarbon + oxygen → carbon dioxide + water

define crude oil

a fossil fuel made of many compounds

what are 4 features of crude oil?

formed from plankton

finite resource

needs high temperature and pressures

oil rigs used to remove from rocks

define fractional distillation

separating compounds from crude oil using heat

describe the fractional distillation process

feed crude oil into the distilling chamber

heat it until most of it is a gas

pass the gaseous mixture into a fractioning column

hot at the bottom cooler at the top

when they reach a temperature lower than its boiling point they condense

hydrocarbons with the most carbons have higher boiling points so they condense quicker

true or false short chain hydrocarbons make better fuels?

true

how do you reduce the size of a long chain hydro carbon?

cracking

define petrochemicals

compounds of crude oil used as feed stock

what are petrochemicals used for?

solvents

polymers

lubricant

detergents

define cracking

thermal decomposition reaction by breaking down molecules by heating them

what are the two types of cracking?

catalytic and steam

describe the process of catalytic cracking

heat hydrocarbons and vaporise them

pass the vapour over hot powdered aluminium oxide

once they have come in contact the hydrocarbons will split apart

describe the process of steam cracking

heat and vaporise hydrocarbons

mix with steam

heat to a very high temperature

they will split

what is the equation for cracking?

long chain alkane → shorter alkane +alkene

define alkene

a homologous series with double bonds (unsaturated)

how do you test for alkenes?

Bromide test

describe the bromide water test

add bromine water to an suspected alkene, if it is an alkene it will go from orange to colourless

if you add alkenes together what do you get?

polymers

define unsaturated

containing at least one carbon=carbon bond

define addition reaction

adding another molecule to the alkene with a double bond

what is the formula for a hydrogen addition reaction?

alkene + H2→ alkane

how do you change alkenes into alkanes?

hydrogen addition reaction

what are the three addition reactions?

hydrogen

H2O

halogens

what is the equation for the water addition reaction

alkene + H20 → alcohol

after a water addition reaction what must you do?

separate alcohol from unreactive alkene and water

describe the process of separating alcohols from alkenes and water

cool mixture to remove alkene

use fractional distillation to remove water

what do hydrogen and water addition reactions require?

a catalyst

what is the equation for addition halogens?

alkene + bromine → Dibromoalkane

define polymer

one long chain of alkanes

what is the equation for a polymer reaction?

monomers → polymers

what do polymer reactions require?

catalyst and pressure

as there could be thousands of *monomers* what do you draw instead?

draw a repeating unit

define repeating units

same group of atoms that are in the monomers

how do you name polymers?

poly +(monomers name)

define alcohol

a homologous series with OH as its functional group

what are the first 4 alcohols in the homologous series?

methanol

ethanol

propanol

butanol

what is the general formula for alcohols?

CnH2n+1OH

what are properties of alcohols?

flammable

soluble

can be oxidised

define flammability

under go complete combustion in air

what is the equation for flammability in alcohols?

alcohol +oxygen → CO2 +H2O

define solubility

dissolve in water to form a solution

do alcohols have a neutral PH?

yes

what is the equation for oxidation?

alcohol →(oxygen) carboxylic acid

what are the uses of alcohols?

fuel

solvents in industry to dissolve hydrocarbons and lipids

define carboxylic acid

a homologous series with the functional group COOH

how do you name a carboxylic acid?

* anoic acid

what are the order of carboxylic acids?

methanoic acdi

ethanoic acid

propanoic acid

butanoic acid

define a weak acid

an acid that doesn’t fully ionise

if something doesnt fully ionise what happens?

wont release all hydrogen ions

what is the carboxylic acid equation (propanoic acid as example)?

C2H5COOH → c2h5coo- + H+

what is the equation for a carboxylic acid and a metal carbonate?

carboxylic acid + metal carbonate → salt (named by carbonate type+carboxylic acid) + water+ CO2

how do you make a carboxylic acid?

alcohol →(oxidation agent) carboxylic acid

define ester

something with a COO functional group in the middle of the molecule

what are the properties of an ester?

pleasant smell

volatile(evaporates quick)

what are esters found in?

perfume

food colouring

how do you make an ester?

carboxylic acid +alcohol →(acid catalyst) ester +H2O

how do you name an ester?

ethyl+ carboxylic acid +OATE

what is the normal acid catalyst used in making esters?

concentrated sulfuric acid

true or false polyesters are not biodegradable?

false

define dicarboxylic acid

two carboxylic groups

define diol

two alcohol groups

how do you combine dicarboxylic acdis and diols?

gives up OH and H from OH

define dimer

two monomers combined

what must they have to combine to make a polyester?

2 functional groups in each

at least 2 functional groups over all

small molecule given off

define polypeptide

polymers made of amino acids

what are the three naturally occurring polymers?

polypeptides

DNA

Carbohydrates

define DNA

polymer made of nucleotides

define carbohydrates

polymers made of sugars