AQA A Level Chemistry Unit 2 Definitions

 ∆H: Change in chemical energy energy under  under conditions of constant pressure pressure..  ̵ 0̵ : Standard conditions conditions of  of pressure of 1x10 Pa and stated temperature. Also the standard states states of  of reactants reactants and  and products products.. Standard !nthalpy of "ormation: #he enthalpy change $hen 1 mole mole of  of a su%stance is formed from its elements elements $ith  $ith all reactants and reactants  and products products in  in their standard states states.. Standard State: #he most sta%le sta%le form  form of a su%stance under standard conditions.. conditions Standard !nthalpy of com%ustion: #he enthalpy change $hen 1 mole mole of  of a su%stance %urns completely completely in  in oxygen $ith all reactants and reactants  and products products in  in their standard states states.. Hess&s 'a$: #he enthalpy change change for  for a chemical reaction reaction is independent independent of  of the route follo$ed follo$ed.. Speci(c Heat Capacity: #his is the amount in )oules in  )oules of energy re*uired to raise the temperature of 1ml 1ml of  of $ater 1oc.  ∆H: +,-.1/ass/∆#1000234'!S +,-.1/ass/∆#1000234'!S 5ond !nthalpy: #he mean enthalpy change change $hen  $hen 1 mole mole of  of co6alent %onds %onds is  is %ro7en homolytically homolytically in  in the gaseous phase phase.. 8ucleophile: !lectron pair donor donor.. !lectrophile: !lectrophile: !lectron !lectron pair acceptor acceptor.. 9eagent: Chemical3chemicals that react react $ith  $ith an organic molecule molecule.. Su%strate: #he organic molecule molecule that  that undergoes the reaction. Addition 9eacton: An unsaturated unsaturated molecule  molecule ,al7ene2 %ecomes saturated saturated.. !limination 9eaction: Saturated Saturated ,al7ane2  ,al7ane2 %ecomes unsaturated unsaturated.. Su%stitution 9eaction: Saturated Saturated ,al7ane2  ,al7ane2 remains saturated saturated condition: a*ueous reagent. a*ueous  reagent. 5ase: Curly arro$ %egins %egins here  here %ut goes to Hydrogen Hydrogen condition: alcoholic reagent. ynamic !*uili%rium: "or$ards "or$ards and  and %ac7$ards %ac7$ards reactions  reactions proceeding at e*ual rates $ith rates  $ith the concentration of reactants and products as constant. 'e Chatelier&s Principle: ;f $e change the external condition condition of  of a reaction at e*uili%rium the position of e*uili%rium e*uili%rium $ill  $ill mo6e mo6e so  so as to oppose the oppose  the external change. o Compromise: -<0 c temperature and =00atms =00atms pressure.  pressure. Acti6ation !nergy ,! a2: #he minimum energy energy the  the colliding particles particles must  must ha6e for a chemical reaction to occur. ost Pro%a%le !nergy ,!mp2: #his is the hump that ta7es ta7es place on the ax$ell istri%ution >raph >raph.. Catalyst: ?hat ?hat:: A su%stance $hich speeds speeds up  up a chemical reaction %ut remains chemically unchanged unchanged %y  %y the reaction. Ho$:: A catalyst pro6ides an alternati6e Ho$ alternati6e reaction  reaction path$ay path$ay of  of lo$er acti6ation energy. 9eaction 9ate: Change in concentration concentration of  of a su%stance in a unit of time time.. 9eagent of 4xidating Alcohols: Aci(ed Potassium ichromate ,orange2 Product Product of 4xidating Alcohols: Cr@ ,green2+it is an oxidising oxidising agent  agent therefore it is reduced reduced.. 5io+"uels: "uel produced from %iological %iological or  or rene$a%le sources sources.. Car%on 8eutral: 8o 8o net  net increase increase to  to the C4= le6el in the atmosphere. a)or Product: #he most sta%le sta%le intermediate  intermediate forms more often often gi6ing  gi6ing the ma)or product. Polymerisation: 9eaction $hich turns many small molecules into long chain molecules. Ho$ isomers found in ;nfa+red Spectrum: "inger print region uni*ue uni*ue to  to all compounds comparison comparison to  to authentic sample. Primary Alcohols: 4xidised 4xidised to  to Aldehydes Aldehydes then to Car%oxylic Acid Acid.. Seconday Alcohols: 4xidised 4xidised to  to Betones Betones.. 9educing Agents: >ains 4xygen 'oses !lectrons 'oses Hydrogen. 4xidising Agents: 'oses of 4xygen >ains of !lectrons >ains Hydrogen. !lectronegati6ity: A%ility to attract a pair pair of  of shared electrons in a co6alent %ond.. %ond 4res: 8aturally 8aturally occurring  occurring materials from $hich $e can extract extract a  a metal commercially.. commercially Alloys: ixture ixture of  of metals.

Stereoisomerism: Compounds Compounds $ith  $ith the same structural formula formula $ith  $ith %onds arranged dierently in space space.. Structural ;somers: Ha6e the same molecular formula %ut formula %ut dierent structural formulae.. formulae Hydrolysis: Splitting C+D %onds %onds using  using $ater olecular ;on: #he molecule molecule $ith  $ith an electron electron 7noc7ed  7noc7ed o  9adical: An unpaired electron electron.. Su%stitution: 9eplacement of the Halogen Halogen..