A level chemistry paper 2 Questions and Answers

A level chemistry paper 2 Questions and Answers Silver nitrate+ nitric acid + chloride ions White precipitate Silver nitrate+ nitric acid + bromide ions Cream precipitate Silver nitrate+ nitric acid + iodide ions Yellow precipitate Substances that decolorise bromine water Alkenes Electrophiles Electron pair acceptors, attracted to electrons e.g H+ NaF and NaCl Produces misty fumes with conc sulphuric acid NaBr Produces misty and orange/brown fumes with conc sulphuric acid NaI Produces misty fumes, purple vapour, bad egg smell with conc sulphuric acid Le chateliers principle If a factor affecting the equilibrium is changed the equilibrium will shift to oppose this change Enthalpy change The overall temperature change at a constant pressure of a reaction Hess's law The overall enthalpy change of a reaction at a constant pressure is independent to the route taken Why does E-Z isomerism occur Due to the restriction of the double carbon bond Positional isomers The functional group is attached to a different carbon Functional group isomers Same atoms arranged into different functional groups e.g cyclohexane and hexene Dative covalent bond A bond of shared electrons where both electrons are supplied from one of the atoms Kelvin Temperature in degrees Celsius + 273 Metres cubed The unit of volume in ideal gas equation Number of particles= Number of moles x avogadros constant Linear 2 bonding pairs, 0 lone pairs, 180 bond angle Trigonal planar 3 bonding pairs, 0 lone pairs, 120 bond angle Tetrahedral 4 bonding pairs, 0 lone pairs, 109.5 bond angle Trigonal bipyramidal 5 bonding pairs, 0 lone pairs, 90 and 120 bond angle Pyramidal 3 bonding pairs, 1 lone pair, 107 bond angle Bent/ v shaped 2 lone pairs, 2 bonding pairs, 104.5 bond angle Octahedral 6 bonding pairs, 0 lone pairs , 90 bond angle T shaped 2 lone pairs, 3 bond pairs Electronegativity The power of an atom to attract the pair of electrons in a covalent bond Standard conditions 100kPa and 298k Standard enthalpy of formation The enthalpy change when 1 mole of a substance is formed from its elements under standard conditions Standard enthalpy of combustion The enthalpy change when 1 mole of a substance undergoes complete combustion under standard conditions Standard enthalpy of atomisation The enthalpy change when 1 mole of gaseous atoms of a substance are formed from the substance in its standard state under standard conditions Standard enthalpy of neutralisation The enthalpy change when 1 mole of water is produced by the reaction of an acid and a base under standard conditions Mean bond enthalpy The average energy needed to break a certain type of bond over a range of compounds Collision theory For a reaction to take place particles have to collide with the right orientation and sufficient energy Activation energy The minimum amount of energy a particle requires for a reaction to take place Catalyst A substance that increases the rate reaction without being chemically changed or used up in the process Reaction rate The change in concentration or amount of a reactant or product over time Carbonate Produce CO2 when hydrochloric acid added Test for Sulfates Add dilute HCl and barium chloride- White precipitate if positive Stereoisomers The same structural formula but a different arrangement in space Alkanes Saturated hydrocarbons Alkenes Unsaturated hydrocarbons Thermal cracking Form of cracking that takes place at high temperature and high pressure, produces a lot of alkenes Catalytic cracking Form of cracking that takes place at high temperature and slight pressure with a zeolite catalyst. NOx CO Carbon Pollutants produced from internal combustion engines Platinum Catalyst in a catalytic converter Calcium oxide or carbonate Used to neutralise sulphur dioxide in flue gases Calcium Sulfate The salt made when calcium carbonate/oxide reacts with sulphur dioxide Tertiary The most stable structure of a carbocation Primary The least stable structure of a carbocation Plasticiser Molecule that pushes polymer chains apart making them more flexible Rigid PVC Used to make drain pipes and window frames Plasticised PVC Used to make cable insulation, tiles and clothing Conditions for steam hydration ethanol production Hydration of ethene by steam at 300 degrees, pressure 60atm Catalyst for ethanol steam hydration production Phosphoric acid catalyst Conditions for fermentation of glucose Yeast anaerobic conditions, 30-40 degrees c Biofuel Fuel that's made from biological material that's recently died Fossil fuels used for machinery for transport, harvesting Reason why bioethanol is not fully carbon neutral Primary alcohols Oxidised to aldehydes, further oxidised to carboxylic acids Secondary alcohols Oxidised to ketones Tertiary alcohols Not oxidised too stable Potassium dichromate Oxidising agent for alcohols