DF From Sep 2015

A reaction that takes in energy and cools and surroundings - the overall energy change is positive

It is an electrical attraction between atoms or ions and therefore requires energy in order for the bond to break in order to overcome the attractive forces

It is the quantity of energy needed to break a particular bond in a molecule, also called bond dissociation enthalpy

The average quantity of energy needed to break a particular bond

Yes, it means more attraction between nuclei and the electrons so greater attractive forces. Greater attractive forces mean a smaller bond length because it takes longer for repulsive forces to balance it. The shorter bond length means a larger bond enthalpy because there is greater attractive forces to overcome

Bond making is exothermic

The enthalpy change when molar quantities of reactants as stated in the equation react together under standard conditions.

1 atm (pressure) 298K (temperature) All the substances in their standard states.

Energy transferred = specific heat capacity x mass x change in temperature

The enthalpy change that occurs when one mole of a substance is burnt completely in oxygen under standard conditions in standard states.

The enthalpy change when one mole of a compound is formed from its elements under standard conditions in standard states.

The enthalpy change when one mole of hydrogen ions react with one mole of hydroxide ions to form one mole of water under standard conditions and in solutions containing 1moldm^-3.

A reaction that gives out energy and heats the surroundings - an overall negative energy change

Loss of Biodiversity Non-food crops make food scarce / more expensive Deforestation Depletion of soil nutrients

Can be made from waste vegetable oil Carbon neutral (excluding energy for harvesting, processing and distributing the fuel) It is biodegradable No sulphur (so no sulphur dioxide/acid rain) Less particulates Less Carbon Monoxide Less unburned hydrocarbon

Renewable via hydrolysis of water Can be sent down natural gas pipelines Can be used in internal combustion engine or in fuel cells When burnt, only forms water

Electrolysis might use fossil fuel electricity source Less energy dense than petrol and diesel Sometimes produced from methane (fossil fuel source) Can produce NOx in internal combustion engine (acid rain)

1) x10^-6 2) x10^-3 3) +273 4) x10^3

1) convert units: 3027cm^3 = 0.003027 m^3 25°C = 298K 400kPa = 400000 Pa 2) rearrange pV=nRT to n = pV/RT 3) substitute in values: 400000x0. 003027 / 8.314x298 = 0.4889….. moles n = 0.488 moles

1) convert units: 200kPa = 200000 Pa 23°C = 296 K 2) rearrange pV=nRT V= nRT/p 3) substitute in values: 8. 31x1x296/200000 = 0.1231… V= 0.0123 M^3

As long as the starting and finishing points are the same, the enthalpy change will always be the same, irrespective of how you get from start to finish.

Compounds that contain one or more benzene rings.

Compounds that do not contain any benzene rings.

Modifiers that are responsible for the characteristic chemical reactions of molecules.