Speed of reaction, QA, Chemical enegetics, Metals (combine chem)

Rateof reaction:A) Measuringmassof reactantsDownwardcurve:- Gradient isat thesteepest at thestart, indicatingthat reactantsarereactingat theirmaximumspeed.- Eventuallybecomelesssteepbecausereactantsarebeingusedupandsothespeedof reactiondecreases.- Eventuallythereactioncurvewill endwitha0gradient that indicatesthecompletionof reactionwheneitherof thereactantsareusedup. B) Measuringchangeinvolumeof gaseousproducts- Reactionisthefastest at thestart of thereactionwhenthereactantsareatthemaximumamount.- Thegradient progressivelygetslesssteepasthereactantsarebeingusedupandreactionslowsdown.- Graphbecomeshorizontal asthereactionstopswhenoneof thereactantsisusedup. Factorsaffectingspeedof reaction:1. Concentrationof thereactants(solutions)2. Pressure(gas)3. Particlesizeof reactants(solid)4. Temperature A) Concentrationof reactants:- Highertheconcentration, thefasterthespeedof reaction.- Increasingconcentration->Increasingnumberof reactantsparticlesperunit volume.- Lessdistancebetweenreactant particlesandhigherfrequencyof collisionsbetweenthem, causingincreaseinrateof reaction.- Steeperthegradient.- If concentrationof alimitingreagent isdoubled, theamount of productformedwill alsodouble.

B) Pressureof gaseousreactants:- Higherthepressure, fasterthereaction.- Increasingpressureof gaseswill decreasethedistancebetweenthereactantparticles, thusincreasingthenumberof reactantsperparticleunit volume.(Sameasconcentration)- Higherfrequencyof effectivecollisionbetweenreactant particles.- Steepergradient at thestart of reaction.- Amount of product formedremainsthesame. C) Particlesizeof solidreactants:- Thesmallerthereactant particles, thefasterrateof reaction.

- Smallerparticles—>Surfaceareaforreactionislarger—>morechancesofeffectivecollisionsbetweenreactant particles.- Amount of product formedremainsthesame. D)Temperature:- Temperaturerises, theparticlesof thereactantsgainmorekineticenergyandmovefaster.- Causesthenumberof particleswithenergyhigherthantheactivationenergytoincrease. (Abletoovercometheactivationenergy)- Increasesthefrequencyof effectivecollisionsbetweenthereactingparticles.Hence, speedof reactionincreases.- Steepergradient at thestart.- Amount of product formedremainsthesame. Qualitativeanalysis:- Cationsareidentifiedusingtwomainalkalinereagents:->Aqueoussodiumhydroxide->Aqueousammonia A) Test forcationsusingaqueoussodiumhydroxide:- Sodiumhydroxidewill dissociateinwatertoformsodiumhydroxideions.->NaOH(aq)—>Na+(aq)+OH-(aq)

- Changes: Precipitationandeffervescent 1 Cationpresent (+) addingafewdrops addinginexcess AluminiumAl 3+ whiteprecipitateisformed. whiteprecipitatedissolvestogiveacolourlesssolution.(Solubleinexcess) ZincZn 2+ whiteprecipitateisformed. whiteprecipitatedissolvestogiveacolourlesssolution.(Solubleinexcess) Ca 2+ whiteprecipitateisformed. whiteprecipitateisinsoluble. Copper(ll),Cu 2+ Light blueprecipitateisformed. light blueprecipitateisinsoluble. Iron(ll),Fe 2+ greenprecipitateisformed. greenprecipitateisinsoluble. Iron(lll),Fe 3+ reddish-brownprecipitateisformed. reddish-brownprecipitateisinsoluble. Ammonium,NH 4+ Noprecipitateisformed,thesolutionremainscolourless. Uponheating, apungentgasisevolvedwhichturnsredlitmuspaperblue. Novisiblereaction. B) Test forcationsusingaqueousammonia:- Ammoniadissociatespartiallyinwatertoformammoniumandhydroxideions. Hence, concentrationof OH- (aq)ionsinaqueousislow.->NH 3+ (g)+H2 O(l)<—>NH 4+ (aq)+OH - (aq) 1 Thevigorousreleaseof gas.

Cationpresent addingafewdrops addinginexcess Aluminium,Al 3+ whiteprecipitateisformed. whiteprecipitateisinsoluble ZincZn 2+ whiteprecipitateisformed whiteprecipitatedissolvestogiveacolourlesssolution.(Solubleinexcess) CalciumCa 2+ novisiblereaction Duetothelowconcentrationofhydroxideionspresent inaqueousammonia. Iron(ll), Fe 2+ Greenprecipitateisformed greenprecipitateisinsoluble. Iron(lll), Fe 3+ Reddish-brownprecipitateisformed reddish-brownprecipitateisinsoluble. - Anionsareusuallyidentifiedusing4typesof test reagents:->Dilutenitricacid->AqueousSilvernitrate/nitricacid->Aqueousbariumnitrate/nitricacid->Aqueoussodiumhydroxide/aluminiumfoil - Changes:->Colourof precipitation.->Gasgivenoff. Anion(-) Test observation Carbonate 1. Adddiluteacid.2. Passanygasgivenoffintolimewater. Effervescenceisobserved. Colourless, odourless, gasevolvedtoformwhiteprecipitatewithlimewater. Gasiscarbondioxide.

Nitrate 1. AddaqueousNaOH, followedbysmall piecesofaluminiumfoil/powder.2. Warmthemixtureandtest anygasgivenoffwithmoist redlitmuspaper. Effervescenceisobserved. Colourless, pungent gasevolvedtoturnmoist redlitmuspaperblue. Gasisammoniagas. Chloride Adddilutenitricacid(toremovedanycarbonatepresent), followedbyaqueoussilvernitrate. *Dilutehydrochloricacidcannot beused, Whiteprecipitateisformed. Iodine Adddilutenitricacidfollowedbyaqueoussilvernitrate. Yellowprecipitateisformed. Sulfate Addnitricacidfollowedbyaqueousbariumnitrate. whiteprecipitateisformed. - Identificationof gas:—>Colour, odour, reactionwithspecificchemical test.A) Chemical test: Gas Test Observationsandexplanations Ammonia Placemoist redlitmuspaperat themouthofthetube. Note*: Litmuspapermust bemoist otherwisenoobservationcanbemade. Moist redlitmuspaperturnsblue. NH3 , gasdissociatespartiallyinwatertoformhydroxideions, OH-,OH+ionsturnsredlitmuspaperblue.

Chlorine Placemoist bluelitmuspaperat themouthofthetest tube. Moist bluelitmuspaperturnsred, andthenbleachwhite. Cl2 Sulfurdioxide Placeapieceof filterpaperdippedinacidifiedpotassiummanganate(Vll)at themouthof thetest tube. Purpleacidifiedpotassiummanganate(Vll)turnscolourless. Redoxreactiontakesplace. Sulfurdioxideisareducingagent. ReducespurpleMnO4- tocolourlessMn 2+ ionsinsolution. Carbondioxide Passgasevolvedintolimewater, Ca(OH)2 Whiteprecipitateisformed. Whiteprecipitateisformedis, CaCO3. Ca(OH)2 (aq)+CO2 (g)—>CaCO3 (S)+H2 O(l) Oxygen Insert aglowingsplintintoitstest tube. Glowingsplint isrelighted/rekindled. Oxygensupportsburningcombustion. Hydrogen Insert alightedsplintintothetest tube. Lightedsplint isextinguished 2 witha‘pop’ sound. Reactivityseriesof metal: 2 Keywordfor answering.

- Thehigherthemetal isintheseries, themorereactiveit is.- Themorereactiveametal is, thegreateritstendencytodonateitsvalenceelectronstoformapositiveionwithastableelectronicconfiguration.- Morereactiveametal, themoredifficult it istobeextractedfromitsore. P—Potassium(K)S—Sodium(Na)C—Calcium(Ca)M—Magnesium(Mg)A—Aluminium 3 (Al)C—Carbon[C]Z—Zinc(Zn)I —Iron(Fe)L—Lead(Pb)H—Hydrogen[H]C—Copper(Cu)S—Silver - Determiningreactivityof metal:- Thiscanbeestablishedbystudyingthereactionof metalswithcoldwaterorsteamandacids. A) Reactionof metalswithcoldwaterorsteam.- Somemetalsreact withcoldwatertoformmetal hydroxidesandhydrogengas.- Sodium+coldwater—>sodiumhydroxide+hydrogen->E.g. 2Na(s)+2H2O(l)—>2NaOH(aq)+H2(g)- Somemetalshoweverdonot react withcoldwaterbut steamtoformmetaloxidesandhydrogengas.- Zinc+steam—>zincoxide+hydrogen->Zn(s)+H2O(g)—>ZnO(s)+H2(g) Metal Reactionwithwater Reactionwithsteam K- Potassium Reactsexplosively React explosively Na- Sodium Reactsviolently Reactsexplosively 3 Not inthe2024syllabus.

Ca- Calcium Reactsreadily Reactsexplosively Mg- Magnesium Reactsveryslowly Reactsviolently Zn- Zinc Noreaction Reactsreadily Fe- Iron Noreaction Reactsslowly B) Reactionof metalswithdilutehydrochloricacid(HCL)1. Somemetalsreact withdilutehydrochloricacidtoformasalt andhydrogengas.- Sodium+hydrochloricacid—>2Nacl (aq)+H2(g) Metal Reactionwithdilutehydrochloricacid K- Potassium Reactsexplosively Na- Sodium Reactsexplosively Ca- Calcium Reactsviolently Mg- Magnesium Reactsrapidly Zn- Zinc Reactsmoderatelyfast Fe- Iron Reactsslowly Pb- Lead Reactsveryslowly - Metalsbelowleadinthereactivityseriesdonot react withdilutehydrochloricacid. C)Displacement reactionsof metalsinreactivityseries.- Ahighermetal whichhashigherreactivitycandisplaceanymetalbelowit.- Displacement reactionsareuseful forextractionof metal. Ametalcanbeextractedfrom:->solubleaqueoussalt of themetal.->oxideof themetal.- twoobservati