1 He (1) for each number, (1) for symbol (ed unless H) 1 3 1

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Muriel Sanders
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1 zau am scneme danuary ruvr CKM~STRY 6r~ '~q Question Expected Answers s ai (nuclear) fusion aii they result in the formation of otherhrgerheavier elemenwatmdnuclei (not helium) NOT generation of light in the Sun ALLOW references to fusion processes on Earth giving energy. ( bi bii same numberlamount of protondone protonl same atomic number (): NOT same element GNORE references to electrons different numbers of neutrons/ mass numberlone and two neutrons/ () neutrons is 'con" unless neutrons in b(i) GNORE different massed atomic masses c i llcii He () for each number, () for symbol (ed unless H) ALLOW : H + di H for marks., n sams for the '.- Award one less mark if positive ion shown. radioactive enables position to be foundlenables follawingl tmcing of isotope/samplel substance (AW, or implied) Geiger (-Muller) wunterl~. ACCEPT Geiger phoneticany. gnore qualifications (eg'millef ) spark counter photographic plate el bbcwdark lineslgaps (); on coloured background lcantinuous spectrumlspectrum of visible light (AW() second ma& depends on first e iii e ii electrons (must be present) horizontal energy levels (two lines minimurn)(l); smaller separation at top (three levels acceptable) ();vertical line going up between levels (); lines going down as well {unless correctly labelled) are 'conm. two (or more) lines upwards of different kngth () ; a r m frwn'sidei (except labels) are 'con' Circular model -can award all except first mark.

2 Page of 5 ai 850 i i iu n "ll- n n n a ii CHg C0 + H0 \ () for products () for completely correct. ecf from (i) ALLOW doubled a iii Bonds broken: x (;C x C-H-0 5 x0..0=90 Total () award fseen, ignore sign Bonds made 6 x C-0 = 80 8x0-Hn7 Total 85 () award fieen, ignore sign bi b ii c d e f Broken - Made (AW) () =-05 w morl (calculafion [assume "broken - made " unless shown], sign [must be consirtent with calculation] and units)(l) alkane(s) 0 x -880 () M i sign in answer () Murk sepmately B() &methylpropane/, - &nethylpropnne(l) NOT - dimethylpropane D() methylbutanel - methylbutane() ALL0 W "methfy " and errors in dashes, commas and gaps. True because bonds broken and made (AWX); are the same (NOTsimiar)lsame number and typeof bond GC, GH () autoignition knockinglpinking (); less likely/ preventedstopped (); B ecf(unlecs A and C charen)(l) (More) branched () separately GNORE rderences to volatility a 57 (accept ) (); Negative sign and units () sepwatefy, Differences roughly the samdmarhs shown (): since CHisame bonds added one more U G C/ next member of series () these reasons sepwateyfiom value. NOT multiplication methods

3 Page of Sesslon g named pollutant () how it arises in petrol enginel) indication of how LPG might di& (not newssady comct) () 6 Two leh from: (ignore any treatment of COZ) oxides of sulphur/ named oxidd fonnula/sox oxides of nitrogen/ named oxidd fomulamox sulphur (compounds) in he burn/ - oxidisel react with air nitrogen (in air, implied) burnsloxidised reacts with air &cuss pmsendabsence of sulphur ~~mwunds in LPG mention of sparkheatltemperature of engine in LPG simple comparison $temp point made earfier COl~%lhfl monoxidefc?carbonfs oot hydrocarbons incomplete combustion incomplete combustion discuss likelihood in LPG, discuss likelihood in LPG cugine. g Qwc At least two sentences Lbgical At least.wo of these wonidphrases used comctly: qlphw compoundr, burdoxidisdreacl/comburt, ' t e m P e p k of engine, ~&ocmbon/flel lncompfete combustion. - Tick with C! in body of scrbt, "lqn in marlpin h ' energy densitu may be led need to keep it iquefiedpnssw higher flammability loss of fuel by evaporation NOT s tow as a gas NOT cost. ii iricnase lghw&5 qualifications i ii, mon ways of arranging (); the molcculw/ particles () NOT atom depend onftst mmk more disorder/more random dlrtribution score ()

4 Page of 5 ai CaCO)(s) OUCa //0 (s) + C0 (g) () for equation () for &e symbol depends onfrkt ( s iii aiv alkali(neflase/basic () ph paperl"'universal indicatoflnamed indicator /ph meter/ ph test () Result comct colourl ph>7 () NOT "alkaline" alone. ' bi or a test involving precipitation: Suitable reagent (); ppt () Mr&C0 ' loo(); Molts acoj '.5 x Mr (); 0.05 scorerfist hvo marks.... bii ci Moles x ec/(l) 0.6 dm 600 cm tube or flask joined without leaks (and clear passage of gas shown) to () ( gas r)ringe or collection over water (in calibrated tube) (). ] Ca.8.8 () ALLOW lssp6sip6s or [Ar] s c ii lobe&: solid (must be in flask or tube) (can be shown as tins on flask or tubex); heat source, provided something is be in^ heated () Mg.8 () ALLOW ~ ~ ~ or ~ we] s: ~ ~ s ~ electmna io outer shell () c iii all form + ions () ALLOW $@en in c ii cartmate is - () "on charges cancev balance" scores () if neither of the others scored "all Group metals have same charge on their ions (AW) scorn () magnesium carbonatdmgc0/magnesiumlmg. dii mare soluble/ increases - - two double bonds only round carbon (); two dots and two crasser anywhere between atoms. rest of detail on oxygens () lone pairs must be paired 80 (); edfiom diagram (but 80 scorn with wronglno diagram) ' two groups of elechoaslareas of electron density( ); eeom diagram, not necersmily consirlent with angle ( repel (); in context ofelectrons get a far away fmo each other as they cau () allow frefming to oxygen atom

5 Page 5 of //0 ai speeds up a reaction () ' a ii bi b ii c unchanged (chemically) a t e n d l not used upl lowers activation mergyen~ pmvidu alternative route () sepmotely heterogeneous C0H () 0 (, or )CHg () + a CH compound which balances equation () ~strtccturalfonnulae/f;ll struchualfwmuloe given, mmimum mmb, btd GNORE ifthese are given in addition to molecular formulae v- () for three carbons; () for one double bond (mark separately) ecffom fonnulo in b () Correct with blobs scores () Three from: Make shorter lsrnaller moleculeslchdalkanes () m& volatilalburn more easily (); improved octane rating/ less auto-ignitionhocking () insufficient short chain (alkanes) in crude oiv Supply demand impliedlshorkr chains art more useful than long chains () -

2850 Chemistry (Salters): Chemistry for Life. January Mark Scheme

2850 Chemistry (Salters): Chemistry for Life. January Mark Scheme 850 Chemistry (Salters): Chemistry for Life January 004 Mark Scheme The following annotations may be used when marking: X = incorrect response (errors may also be underlined) ^ = omission mark bod = benefit