chemistry paper 2

using the amount of product used, or amount of product formed over time.

Rate of reaction = amount of reactant used/time

Rate of reaction = amount of product formed/time

It can be measured by the mass in grams or by volume in cm3

Units of rate of reaction can be given as g/s or cm3/s

Quanitiy of reactants can be used in terms of moles (instead of mass or volume) and therefore, units for rate or reaction in mol/s

*Draw tangets to curves and use the slope of the tanget, then calculate the gradient of a tanget to the curve on these graphs as a measure of rate of reaction at a specific time

concentration, pressure surface area, temperature, catalysts.

chemical reactions can occur only when reacting particles collide with each other and with sufficient energy.

the minimum amount of energy that particles must have to react

increases the frenquency of collison and so increases the rate of reaction.

Increasing the temperature increases the frequenecy of collisions and makes the collisions more energetic, and so increases the rate of reaction.

Catalysts are substances that speed up chemical reaction without being changed or used up during the reaction.

Enzymes act as catalysts in biological systems.

Catalysts decrease the activation energy, this increases the proportion of particles with energy to react.

Can be changed by changing the conditions (e.g. for forwards reactions use hot conditions and for reverse use cool)

If a reversible reaction is endothermic one way, it is exothermic in the opposite directions. The same of amount of energy is transferred each way (for one the energy will be lost and for the other the same amount will be gained)

When a reversible reaction occurs in a closed system, equillibrium is reached when the reactions occur at exactly the same rate in each direction.

The relative amounts of all reacting substances at equillibrium depened on the conditions of the reaction. If a system is at equillibrium and a change is made to any of the conditions, then the system responds to counteract the change (Le Chateliers principle)

If the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again.

Position of equillibrium shifts towards products so more product is produced until equillibrium is reached again

position of equillibrium shifts towards reactants so more reactant is produced until equillibrium is reached again.

equillibrium moves in the direction of the endothermic reaction. (e.g if fowards reaction is endothermic and temperature is increased, equillibrium shifts right to produce more product).

Equilibrium moves in the direction of the exothermic reaction.

decreased

exothermic - increases yeild of reaction. endothermic - decreases yeild of reaction.

In a gaseous reaction, an increase in pressurenwill favour the reaction that produces the least number of molecules as shown by the symbol equation for that reaction.

if pressure is increased, equilibrium shifts to the side of equation with fewer moles of gas making more product

A finite resource found in rocks and is the remains of ancient biomass, mainly contains plankton. (crude oil is a mixture)

You can seperate substances in the mixture using physical proccesses such as distillation

Mostly consist of molecules made up of hydrogen and carbon only (hydrocarbons). Most of saturated hydrocarbons are called alkanes.

Hydrocarbons have a general formula of CnH2n+2

using covalent bond diagrams

Methane, ethane, propane, butane (monkeys eat peanut butter)

Oil is heated in fractionating column, oil evaporates and condenses at a number of different temperatures

They can be seperated into fractions, each of which have a similar number of carbon atoms

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

Boiling points and viscosity increase as molecules get bigger, volatility and flammability decrease as molecules get bigger. They have poor reactivity.

When large hydrocarbons are thermally broken down into smaller and useful molecules.

Reactant heated to vapor, passed over a hot catalyst or heated with vapor

mixed with steam and heated to high temperstures so that thermal decompostion reactions can occur

used as polymers and starting materials for synthesis

Includes alkanes and unsaturated hydrocarbons called alkenes

Alkenes react with bromine water, turning it from orange to colourless

They are useful as fuels since they have shorter chains than alkanes they started with with, making them more flammable so a better fuel

Solvents, lubricants, polymers and detergents

ethene, propene, butene and pentane (eat properly but politely)

Alkenes are hydrocarbons with the functional group C=C

Alkenes react with oxygen in combustion reactions, they burn in air with smoky flames because of incomplete combustion (carbon monoxide is formed)

By the addition of atoms across the C=C double bond so that the double bond becomes a single C-C bond

Ethene - C2H4. Propane C3H6. Butane C4H8. Pentane C6H10.

An organic compound that contains an -OH functional group

methanol, ethanol, propanol, butanol (monkeys eat purple bananas)

They burn in air which produces carbon dioxide and water

They dissolve in water to form a neutral solution (has a ph of 7)

They react with sodium to produce hydrogen and a salt (H has been given off and Na has been added)

They react with oxidising agents to form carboxylic acids

methanol - used to make chemical feedstock in antifreeze to make biodesel. Ethanol - tha main alcohol in alcoholic drinks, used as solbents and fuel. All 4- used as fuels

Can be produced by fermentation of sugar with yeast using renewable sources.

35 degrees, anaerobic (without oxygen) and yeast enzyme catalyst

ethanoic acid is a member of the carboxylic acids, they have the functional group COOH

Methanoic acid, Ethanoic acid, Propanoic acid, Butanoic acid

They dissolve in water to produce acidic solutions (ph less than 7)

They react with metak carbonates to produce carbon dioxide (turns limewater cloudy), a salt and water

They react with alcohols in the presence of an acid catalyst to produce esters

Can be used to make polymers such as (poly(ethene) and poly(propene) by addition polymerisation

A polymer is a long chain molecule which is made by lots of smaller molecules joining together

c=c bonds open up and many smaller molecukes (monomers) join together to form a chain, No other products are made. (called addition polymerisation reaction)

Draw the bonds coming off the c’s out of the brackets and the little ‘n’ (means there are large numbers of these molecules joined together

involves monomers with two functional groups

When they react, they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions

They are produced from two different monomers with two of the same functional groups on each monomer

They have two different functional groups in a molecule (an anime group and a carboxylic acid group)

They react by condensation polymerisation to produce polypeptides

They can be combined in the same chain to produce proteins

it encodes genetic instructions for the development and functioning of living organisms and viruses