(Get Answer) – Determination of Rate Law

Paper, Order, or Assignment Requirements  Determination*of*the*Rate*Law Michael(W.(Burand,(Chris(Knutson,(Oregon(State(University(Department(of( Chemistry Introduction The!rate!of!a!chemical!reaction!is!measured!by!finding!out!how!long!it!takes!to!consume!a!definite! amount!of!reactant!or!to!form!a!definite!amount!of!product.!Since!we!want!the!rate!to!be!the!same! regardless of!which!product!or!reactant!is!chosen,!the!stoichiometry!of!the!reaction!must!be!taken!into! account.!For!example,!if!the!reaction!is: aA!+!bїcC!+!dD the!rate!of!reaction!is!given!by ƒ‡ ൌ െȟሾ ሿ ܽȟݐ ൌ െȟሾሿ ܾȟݐ ൌ ȟሾሿ ܿȟݐ ൌ ȟሾሿ ݐȟ݀ ǁŚĞƌĞȴ΀ ΁ ŝƐƚŚĞĐŚĂŶŐĞŝŶĐŽŶĐĞŶƚƌĂƚŝŽŶŽĨƌĞĂĐƚĂŶƚ ŝŶƚŚĞƚŝŵĞŝŶƚĞƌǀĂůȴt,!etc.!Note!that!since!A! and!B!are!being!consumed!a!minus!sign!is!placed!in!front!of!their!rates!of!change!so!that!the!rate!of! reaction!is!always!a!positive!number. The!objective!of!this!experiment!is!to!determine!the!rate!law!of!a!chemical!reaction.!The!rate!law!is!a! mathematical!relationship!between!the!rate!of!the!reaction!and!the!concentrations!of!the!species! involved!in!the!reaction.!Rate!laws!are!sometimes!very!complicated,!but!if!we start!out!using!a!mixture! containing!only!reactants!and!no!products,!the!rate!law!generally!takes!the!following!form: ƒ‡ ൌ ݇ሾ ሿ௫ሾሿ௬ Where!x and!y are!usually!small!integers!and!k is!a!constant!(the!rate+constant)!at!constant!temperature.! The!value!of!x is!called!the!order of!the!reaction!with!respect!to![A],!and!y is!the!order!with!respect!to! [B].!!It!is!important!to!note!that!x and!y have!no!relationship!to!the!stoichiometric!coefficients!a and!b,! and!that!x and!y must%be%determined%experimentally. ƒ The!rate%law is!the!mathematical!relationship!between!the!rate!of!reaction!and!the! concentrations!of!the!species!involved!in!the!reaction. ƒ The!order of!a!participant!in!the!reaction!is!the!value!of!the!exponent!to!which!its!concentration! is!raised!in!the!rate!law!for!the!reaction. The!value!of!x can!be!determined!by!measuring!the!initial!rate!of!reaction!when!changing![A]!while! holding![B]!constant.!For!example,!suppose!the!initial!reaction!rate!increased!by!a!factor!of!four!when! [A]!was!doubled!and![B]!was!unchanged.!!In!other!words,![A2]!=!2[A1]!and![B2]!=![B1]!(since![B]!was!held! constant).