AQA GCSE Chemistry Yield and Atom Economy PDF

AQA​ ​GCSE​ ​Chemistry Topic​ ​3:​ ​Quantitative​ ​chemistry ​ ​Yield​ ​and​ ​atom​ ​economy​ ​of​ ​chemical​ ​reactions (chemistry​ ​only) Notes (Content​ ​in​ ​bold​ ​is​ ​for​ ​Higher​ ​Tier​ ​only) www.pmt.ed...

AQA​ ​GCSE​ ​Chemistry Topic​ ​3:​ ​Quantitative​ ​chemistry ​ ​Yield​ ​and​ ​atom​ ​economy​ ​of​ ​chemical​ ​reactions (chemistry​ ​only) Notes (Content​ ​in​ ​bold​ ​is​ ​for​ ​Higher​ ​Tier​ ​only) www.pmt.education Percentage​ ​yield Percentage​ ​yield​ ​=​ ​ ​ ​ ​ ​ ​ ​ ​Amount​ ​of​ ​product​ ​produced​​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​x​ ​100 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​Maximum​ ​amount​ ​of​ ​product​ ​possible It​ ​is​ ​not​ ​always​ ​possible​ ​to​ ​obtain​ ​the​ ​calculated​ ​amount​ ​of​ ​a​ ​product​ ​for​ ​3 reasons: o Reaction​ ​may​ ​not​ ​go​ ​to​ ​completion​ ​because​ ​it​ ​is​ ​reversible o Some​ ​of​ ​the​ ​product​ ​may​ ​be​ ​lost​ ​when​ ​it​ ​is​ ​separated​ ​from​ ​the​ ​reaction mixture o Some​ ​of​ ​the​ ​reactants​ ​may​ ​react​ ​in​ ​ways​ ​different​ ​to​ ​the​ ​expected reaction Yield:​ ​amount​ ​of​ ​product​ ​obtained To​ ​calculate​ ​the​ ​theoretical​ ​mass​ ​of​ ​a​ ​product​ ​from​ ​a​ ​given​ ​mass​ ​of​ ​reactant and​ ​the​ ​balancing​ ​equation​ ​for​ ​the​ ​reaction: o Calculate​ ​mol.​ ​of​ ​reactant​ ​by​ ​using​ ​mol.​ ​=​ ​mass​ ​/​ ​molar​ ​mass o Use​ ​balancing​ ​numbers​ ​to​ ​find​ ​mol.​ ​of​ ​product​ ​(e.g.​ ​2HCl​ ​+​ ​Mg​ ​->​ ​MgCl​2 if​ ​you​ ​have​ ​2​ ​mol.​ ​of​ ​HCl,​ ​you​ ​would​ ​divide​ ​by​ ​2​ ​to​ ​get​ ​1​ ​mol.​ ​of​ ​MgCl​2​.) o Calculate​ ​theoretical​ ​mass​ ​of​ ​a​ ​product​ ​by​ ​then​ ​using​ ​mass​ ​=​ ​mol.​ ​x molar​ ​mass Atom​ ​economy A​ ​measure​ ​of​ ​the​ ​amount​ ​of​ ​starting​ ​materials​ ​that​ ​end​ ​up​ ​as​ ​useful​ ​products Important​ ​for​ ​sustainable​ ​development​ ​and​ ​for​ ​economic​ ​reasons​ ​to​ ​use reactions​ ​with​ ​high​ ​atom​ ​economy =​ ​(Mr​ ​of​ ​desired​ ​product​ ​from​ ​reaction​ ​/​ ​sum​ ​of​ ​Mr​ ​of​ ​all​ ​reactants)​ ​x​ ​100 Possible​ ​reasons​ ​why​ ​a​ ​particular​ ​reaction​ ​pathway​ ​is​ ​chosen/not​ ​chosen: atom​ ​economy,​ ​yield,​ ​rate,​ ​equilibrium​ ​position​ ​and​ ​usefulness​ ​of​ ​by-products www.pmt.education