Physical Sciences Grade 12 Paper 2 NSC June 2019 Memo

Downloaded from hlayiso.com SENIOR CERTIFICATE EXAMINATIONS/ NATIONAL SENIOR CERTIFICATE EXAMINATIONS SENIORSERTIFIKAAT-EKSAMEN/ NASIONALE SENIORSERTIFIKAAT-EKSAMEN PHYSICAL SCIENCES: CHEMISTRY (P2) FISIESE WETENSKAPPE: CHEMIE (V2) 2019 MARKING GUIDELINES/NASIENRIGLYNE MARKS/PUNTE: 150 These marking guidelines consist of 16 pages./ Hierdie nasienriglyne bestaan uit 16 bladsye. Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 2 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 1/VRAAG 1 1.1 C  (2) 1.2 A  (2) 1.3 C  (2) 1.4 A  (2) 1.5 D  (2) 1.6 C  (2) 1.7 D  (2) 1.8 D  (2) 1.9 C  (2) 1.10 A  (2) [20] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 3 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 2/VRAAG 2 2.1 Unsaturated/Onversadig  - ANY ONE/ENIGE EEN: • C/It has a triple/multiple bond.  C/Dit het 'n trippelbinding/meervoudige-binding. • C/It has a triple/multiple bond between C atoms. C/Dit het 'n trippelbinding/meervoudige-binding tussen C-atome. • C/It does NOT contain the maximum number of H atoms bonded to C atoms. C/Dit bevat NIE die maksimum getal H-atome gebind aan C-atome nie. • Compound C is an alkyne./Verbinding C is ‘n alkyn. (2) 2.2 2.2.1 D (1) 2.2.2 B (1) 2.2.3 C (1) 2.2.4 E (1) 2.3 2.3.1 C C  (1) 2.3.2 H H H H  O H H H C C C C O C C C H  H H H H H H (2) Marking criteria/Nasienriglyne: • Whole structure correct: Hele struktuur korrek: 2 2 • Only functional group correct:/Slegs funksionele groep korrek: Max/Maks.: 1 2 IF/INDIEN: • More than one functional group/Meer as een funksionele groep: 0 2 • If condensed or semi structural formula used:/Indien gekondenseerde of semi- struktuurformule gebruik: Max/Maks. 1 2 Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 4 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 2.3.3 H Marking criteria/Nasienriglyne:  • Three C atoms in longest chain.  H C H Drie C-atome in langste ketting. H H • One methyl substituent on C2.  Een metielsubstituent op C2. H C C C H  IF/INDIEN Any error e.g. omission of H atoms, condensed or H H H semi structural formula/Enige fout bv weglating van H-atome, gekondenseerde of semi- struktuurformule. Max/Maks.: 1 2 (2) 2.4 2.4.1 2,3-dibromo-5-methylheptane/2,3-dibromo-5-metielheptaan Marking criteria/Nasienriglyne: • Correct stem i.e. heptane./Korrekte stam d.i. heptaan.  • All substituents (bromo and methyl) correctly identified./Alle substituente (bromo en metiel) korrek geïdentifiseer.  • IUPAC name completely correct including numbering, sequence, hyphens and commas./IUPAC-naam heeltemal korrek insluitende nommering, volgorde, koppeltekens en kommas .  (3) 2.4.2 2C 4 H 10 + 13O 2   8CO 2 + 10H 2 O  Bal  Notes/Aantekeninge: • Reactants  Products  Balancing  Reaktanse Produkte Balansering • Ignore double arrows and phases./Ignoreer dubbelpyle en fases. • Marking rule 6.3.10/Nasienreël 6.3.10. • If condensed structural formulae used:/Indien gekondenseerde struktuur formules gebruik: Max/Maks. 2 3 • Accept coefficients that are multiples./Aanvaar koëffisiënte wat veelvoude is. (3) [17] QUESTION 3/VRAAG 3 3.1 3.1.1 Yes/Ja  - ANY ONE/ENIGE EEN: • Compounds have the same molecular mass.  Verbindings het dieselfde molekulêre massa. • Only one independent variable./Slegs een onafhanklike veranderlike. (2) 3.1.2 Functional group/Homologous series/Type of (organic) compound  Funksionele groep/Homoloë reeks/Tipe (organiese) verbinding (1) 3.2 A/butane/butaan  - Lowest boiling point/weakest intermolecular forces.  Laagste kookpunt/swakste intermolekulêre kragte. (2) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 5 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 3.3 Marking guidelines/Nasienriglyne • Type of IMF in A./Tipe IMK in A. • BOTH B and C have hydrogen bonding./BEIDE B en C het waterstofbinding. • Compare number of sites for hydrogen bonding in B and C./Vergelyk aantal punte vir waterstofbinding in B en C. • Compare strength of IMFs./Vergelyk sterkte van IMKe. • Compare energy required./Vergelyk energie benodig. • Between molecules of butane/compound A are London forces/dispersion forces/induced dipole forces.  • Molecules of compound B/propan-1-ol have one site for hydrogen bonding.  • Molecules of compound C/ethanoic acid have two/more sites for hydrogen bonding.  • Strength of intermolecular forces increases from compound A/butane to compound B/propan-1-ol to compound C/ethanoic acid.  OR Intermolecular forces in compound A/butane are the weakest and intermolecular forces in compound C/ethanoic acid are the strongest. • More energy is needed to overcome/break intermolecular forces in compound C than in the other two compounds.  • Tussen molekule van butaan/verbinding A is Londonkragte/dispersie- kragte/geïnduseerde dipoolkragte.  • Molekule van verbinding B/propan-1-ol het een punt vir waterstof- bindings.  • Molekule van verbinding C/etanoësuur het twee punte vir waterstof- bindings.  • Sterkte van intermolekulêre kragte neem toe van verbinding A/butaan na verbinding B/propan-1-ol na verbinding C/etanoësuur.  OF Intermolekulêre kragte tussen propaan is die swakste en intermolekulêre kragte in verbinding C is die sterkste. • Meer energie word benodig om intermolekulêre kragte in verbinding C as in die ander twee verbindings te oorkom/breek.  (5) 3.4 Butan-1-ol  - Longer chain length./Larger molecule./Larger molecular mass./Larger molecular size./Stronger intermolecular forces./Larger surface area. Langer kettinglengte./Groter molekuul./Groter molekulêre massa/Groter molekuul./Sterker intermolekulêre kragte./Groter oppervlakte. (2) [12] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 6 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 4/VRAAG 4 4.1 4.1.1 Addition (polymerisation)/Addisie-(polimerisasie)  (1) 4.1.2 Ethene/eteen  (1) 4.1.3 Polyethene/polythene  Poli-eteen/politeen (1) 4.2 4.2.1 Dehydration/elimination  Dehidrasie/dehidratering/eliminasie (1) 4.2.2 Catalyst/dehydrating agent/causes dehydration/removes water molecules  Katalisator/dehidreermiddel/veroorsaak dehidrasie/verwyder watermolekule (1) 4.2.3 Prop-1-ene/propene/1-propene  (2 or 0) Prop-1-een/propeen/1-propeen (2 of 0) (2) 4.2.4 H H H  H C C C Cℓ  H H H Marking criteria/Nasienriglyne: • Whole structure correct: Hele struktuur korrek: 2 2 • Only functional group correct:/Slegs funksionele groep korrek: Max/Maks.: 1 2 IF/INDIEN: • More than one functional group/Meer as een funksionele groep: 0 2 • If condensed or semi structural formula used:/Indien gekondenseerde of semi- struktuurformule gebruik: Max/Maks. 1 2 (2) 4.2.5 Addition/Hydration  Addisie/Hidrasie/Hidratering (1) 4.2.6 Propan-2-ol/2-propanol Marking criteria/Nasienriglyne: • Correct stem and functional group i.e propanol/Korrekte stam en funksionele groep d.i propanol  • Name completely correct/Naam volledig korrek: Propan-2-ol/2-propanol  (2) [12] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 7 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 5/VRAAG 5 5. 1 NOTE/LET WEL Give the mark for per unit time only if in context of reaction rate. Gee die punt vir per eenheidtyd slegs indien in konteks met reaksietempo. ANY ONE/ENIGE EEN • Change in concentration  of products/reactants per (unit) time.  Verandering in konsentrasie van produkte/reaktanse per (eenheid) tyd. • Change in amount/number of moles/volume/mass of products or reactants per (unit) time. Verandering in hoeveelheid/getal mol/volume/massa van produkte of reaktanse per (eenheid) tyd. • Amount/number of moles/volume/mass of products formed/reactants used per (unit) time. Hoeveelheid/getal mol/volume/massa van produkte gevorm/reaktanse gebruik per (eenheid) tyd. • Rate of change in concentration/amount/number of moles/volume/mass. Tempo van verandering in konsentrasie/ hoeveelheid/getal mol/ volume/massa.  (2 or/of 0) (2) 5.2 5.2.1 Rate of the reaction/Reaksietempo  (1) 5.2.2 Criteria for conclusion/Kriteria vir gevolgtrekking: Dependent (reaction rate) and independent (concentration ) variables correctly identified./Afhanklike(reaksietempo) en onafhanklike (konsentrasie)  - veranderlikes korrek geïdentifiseer. Relationship between the independent and dependent variables correctly stated. Verwantskap tussen die afhanklike en onafhanklike veranderlikes korrek  genoem. Example/Voorbeeld: Reaction rate increases with increase in concentration./Reaction rate is proportional to concentration. Reaksietempo neem toe met toename in konsentrasie./Reaksietempo is eweredig aan konsentrasie. IF/INDIEN DIRECTLY proportional/DIREK eweredig: Max/Maks.: 1 2 (2) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 8 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 5.3 5.3.1 Activation energy/(The boundary line for the) molecules with (adequate) kinetic energy to make effective collisions.  Aktiveringsenergie/(Die grenslyn vir die) molekule met (genoeg) kintiese energie vir effektiewe botsings. (1) 5.3.2 B (1) 5.3.3 • At a higher temperature particles move faster/have a higher kinetic energy.  By 'n hoër temperatuur beweeg die deeltjies vinniger/het die deeltjies hoër kinetiese energie. • More molecules have enough/sufficient (kinetic) energy.  Meer molekule het genoeg/voldoende (kinetiese) energie. OR/OF More molecules have (kinetic) energy equal to or greater than activation energy. Meer molekule het (kinetiese) energie gelyk aan of groter as aktiveringsenergie. • More effective collisions per unit time/second./Increased frequency of effective collisions. Meer effektiewe botsings per eenheidtyd/sekonde./Frekwensie van effektiewe botsings neem toe. • Reaction rate increases.  Reaksietempo neem toe. (4) 5.4 Curve Y/it was obtained for the reaction where a catalyst was added.  Kurwe Y/dit is vir die reaksie waar 'n katalisator bygevoeg is, verkry. OR/OF Curve X was obtained for the reaction in the absence of a catalyst. Kurwe X is verkry vir die reaksie sonder 'n katalisator. (1) 5.5 Marking guidelines/Nasienriglyne m n • Any formula/Enige formule: n = or/of c =  M V • Substitute/Vervang 0,1 dm3 in n = cV  • Use mole ratio/Gebruik molverhouding: n(S) expected/verwag = ½n(HCℓ) used/gebruik  m • Substitution of/Vervanging van 32 g∙mol-1 in n =  M • SUBSTITUTE in/VERVANG in: n(S)produced / berei m(S)produced / berei x 100 / x 100  n(S)exp ected /verwag m(S) exp ected /verwag • Final answer/Finale antwoord: 56,25% to 60%  Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 9 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne OPTION 1/OPSIE 1 OPTION 2/OPSIE 2 n(HCℓ) used/gebruik = cV  n(HCℓ) used/gebruik = cV  = 0,2 x 0,1  = 0,2 x 0,1  = 0,02 mol = 0,02 mol n(S) expected/verwag = ½n(HCℓ) used/gebruik n(S) expected/verwag = ½n(HCℓ) used/gebruik = ½(0,02)  = ½(0,02)  = 0,01 mol = 0,01 mol m m(S) expected/verwag = nM n(S) produced/berei = M = (0,01)(32)  0,18 = 0,32 g = 32  = 0,0056 mol m(S) prod/berei %yield/opbrengs = × 100 m(S) exp/verwag n(S)prod / berei 0,18 %yield/opbrengs = × 100 = x 100  n(S)exp/verwag 0,32 0,0056 = 56,25%  = x 100  0,01 = 56,25%  (6) [18] QUESTION 6/VRAAG 6 6.1 Reversible reaction/Both forward and reverse reactions can take place./Products can be converted back to reactants.  Omkeerbare reaksie/Beide voorwaartse en terugwaartse reaksies kan plaasvind./Produkte kan terugverander word na reaktanse. (1) 6.2 To favour the forward reaction/production of ammonia./To increase the yield of ammonia./Prevent the decomposition of NH 3 .  Om die voorwaartse reaksie/produksie van ammoniak te bevoordeel./Om die ammoniak-opbrengs te verhoog./Voorkom die ontbinding van NH 3. (1) 6.3 20(%)  (1) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 10 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 6.4 6.4.1 At 500 °C lower yield of ammonia: • The (forward) reaction is exothermic./Reverse reaction is endothermic.  Die (voorwaartse) reaksie is eksotermies./Terugwaartse reaksie is endotermies. • An increase in temperature favours the endothermic reaction.  'n Toename in temperatuur bevoordeel die endotermiese reaksie. • The reverse reaction is favoured. Die terugwaartse reaksie word bevoordeel. OR/OF At 350 °C higher yield of ammonia: • The (forward) reaction is exothermic./Reverse reaction is endothermic.  Die (voorwaartse) reaksie is eksotermies./Terugwaartse reaksie is endotermies. • A decrease in temperature favours the exothermic reaction.  'n Afname in temperatuur bevoordeel die eksotermiese reaksie. • The forward reaction is favoured.  Die voorwaartse reaksie word bevoordeel. (3) 6.4.2 At 350 atm higher yield of ammonia: • An increase in pressure favours the reaction that produces the lower number of moles/number of molecules/volume of gas.  'n Toename in druk bevoordeel die reaksie wat die kleiner aantal mol/aantal molekule/volume gas lewer. • The forward reaction is favoured.  Die voorwaartse reaksie word bevoordeel. OR/OF At 150 atm lower yield of ammonia: • A decrease in pressure favours the reaction that produces the higher number of moles/number of molecules/volume of gas.  'n Afname in druk bevoordeel die reaksie wat die groter aantal mol/aantal molekule/volume gas lewer. • Reverse reaction is favoured.  Die terugwaartse reaksie word bevoordeel. (2) 6.5 6.5.1 1 mol N 2 reacts with 3 mol H 2 to produce 2 mol NH 3 ∴ 2 mol N 2 reacts with 6 mol H 2 to produce 4 (mol) NH 3  (2 or 0) 1 mol N 2 reageer met 3 mol H 2 om 2 mol NH 3 te lewer ∴ 2 mol N 2 reageer met 6 mol H 2 om 4 (mol) NH 3 te vorm (2 of 0) (2) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 11 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 6.5.2 POSITIVE MARKING FROM QUESTION 6.5.1. Marking criteria/Nasienriglyne: • Calculate 35% of 4 mol NH 3 (answer from Q6.5.1).  • Use mol ratio/Gebruik molverhouding n(N 2 ) : n(H 2 ) : n(NH 3 ) = 1 : 3 : 2  • Equilibrium/Ewewig n(N 2 ) = initial/aanvanklike n(N 2 ) - ∆n(N 2 )  Equilibrium/Ewewig n(H 2 ) = initial/aanvanklike n(H 2 ) - ∆n(H 2 ) • Divide by/Deel deur 0,5 dm3.  • Correct K c expression (formulae in square brackets).  Korrekte K c uitdrukking (formules in vierkantige hakies). • Substitution of concentrations into correct K c expression.  Vervanging van konsentrasies in korrekte K c -uitdrukking. • Final answer/Finale antwoord: 0,002  Range/Gebied: 0,00155 to 0,002 (1,55 x 10-3 to 2 x 10-3) 35 n(NH 3 ) = ×4 100 = 1,4 mol N2 H2 NH 3 Initial amount (moles) 6 6 0 Aanvangs hoeveelheid (mol) Change in amount (moles) ratio  0,7 2,1 1,4 verhouding Verandering in hoeveelheid (mol) Equilibrium amount (moles)  5,3 3,9 1,4 hoeveelheid (mol) Equilibrium concentration (mol∙dm-3) Divide by 10,6 7,8 2,8 Ewewigskonsentrasie (mol∙dm-3) 0,5 dm3  No Kc expression, correct substitution/Geen Kc- [NH3 ] 2 Kc =  uitdrukking, korrekte substitusie: Max./Maks. 6 [H2 ]3 [N2 ] 7 (2,8) 2 Wrong Kc expression/Verkeerde Kc-uitdrukking: =  (7,8) 3 (10,6) Max./Maks. 4 7 = 0,002  (7) [17] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 12 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 7/VRAAG 7 7.1 A base forms hydroxide ions (OH-) in water/aqueous solution.  'n Basis vorm hidroksiedione (OH-) in water/waterige oplossing. IF/INDIEN: A base ionises to form hydroxide ions (OH-).  'n Basis ioniseer om hidroksiedione (OH-) te vorm. Max./Maks. 1 2 (2) 7.2 A strong base ionises/dissociates completely  and a weak base ionises/dissociates incompletely.  'n Sterk basis ioniseer/dissosieer volledig en 'n swak basis ioniseer/dissosieer onvolledig. (2) 7.3 HCO 3− (aq) + H 2 O(ℓ)  ⇌ H 2 CO 3 (aq) + OH − (aq)  Bal.  Accept/Aanvaar NaHCO 3 (aq) + H 2 O(ℓ) ⇌ H 2 CO 3 (aq) + NaOH(aq) Notes/Aantekeninge: • Reactants/Reaktanse  Products/Produkte  Balancing/Balansering  • Ignore single arrow./Ignoreer enkelpyl. • Marking rule 6.3.10./Nasienreël 6.3.10. • Ignore phases/Ignoreer fases. (3) 7.4 7.4.1 pH = -log[H 3 O+]  = -log (0,2)  = 0,70  (0,699) (3) 7.4.2 Titration of a weak base and a strong acid.  Titrasie van 'n swak basis en 'n sterk suur. OR/OF The endpoint will be at pH < 7./Die eindpunt sal by 'n pH < 7. (1) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 13 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 7.4.3 Marking guidelines/Nasienriglyne: n m c × Va n a m • Any formulae/Enige formule: c = /n = / a = /c =  V M c b × Vb nb MV • Substitute/Vervang 0,2 mol∙dm-3 & 20 x 10-3/0,02 dm3 or 20 cm3.  • Use mol ratio/Gebruik molverhouding n(XHCO 3 ) : n(HCℓ) = 1 : 1  • Substitute/Vervang n(XHCO 3 ) or/of c(XHCO 3 ) AND/EN 0,4 g.  -1 • M(X) = 39 g∙mol  • X = K/potassium/kalium.  OPTION 1/OPSIE 1 OPTION 2/OPSIE 2 n c a × Va n a c(HCℓ) =  =  V c b × Vb n b n 0,2 × 20  1 ∴ 0,2 =  =  20 × 10 −3 c b × 100 1 n(HCℓ) = 4 x 10-3 mol c b = 0,04 mol∙dm-3 n(XHCO 3 ) = n(HCℓ)  = 4 x 10-3 mol m c( XHCO3 ) = MV m 0,4 n= ∴ 0,04 =  M 1 mol → M(0,1) 0,4 M(XHCO 3 ) 4 x 10-3 mol M(XHCO 3 ) = 100 g∙mol- ∴ 4 × 10 −3 =  → 0,4 g  1 M -1 M = 100 g∙mol-1 M(XHCO 3 ) = 100 g∙mol M(XHCO 3 ) = M(X) + 61 M(XHCO 3 ) = M(X) + M(XHCO 3 ) = M(X) + 61 = 100 61 = 100 ∴M(X) = 39 g∙mol-1  -1 = 100 ∴M(X) = 39 g∙mol  ∴ M(X) = 39 g∙mol-1  X=K X=K OR/OF X=K OR/OF potassium/kalium OR/OF potassium/kalium potassium/kalium (6) [17] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 14 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 8/VRAAG 8 8.1 It is a conductor of electricity/a solid to connect wires to./Pt is inert or unreactive.  Dit is 'n geleier van elektrisiteit/'n vaste stof waaraan drade geskakel kan word./Pt is inert of onreaktief. OR/OF Cℓ−(aq) and chlorine gas are not solids and cannot be used as an electrode. Cℓ−(aq) en chloorgas is nie vaste stowwe nie en kan nie as 'n elektrode gebruik word nie. (1) 8.2 8.2.1 Chemical (energy) to electrical (energy)  Chemiese (energie) na elektriese (energie) (1) 8.2.2 Cℓ 2 + 2e- → 2Cℓ−  Marking guidelines/Nasienriglyne • Cℓ 2 + 2e- ⇌ 2Cℓ− 1 2Cℓ− ⇌ Cℓ 2 + 2e- 0 2 2 − 2Cℓ ← Cℓ 2 + 2e - 2 −- 2Cℓ → Cℓ 2 + 2e - 0 2 2 • Ignore if charge omitted on electron./Ignoreer indien lading weggelaat op elektron. • If charge (-) omitted on Cℓ−/Indien lading (-) weggelaat op 2Cℓ−: Max./Maks: 1 Example/Voorbeeld: Cℓ 2 + 2e- → 2Cℓ  2 (2)  8.2.3 Cr(s) | Cr3+(aq) || Cℓ 2 (g) | Cℓ− (aq) | Pt(s)  OR/OF Cr(s) | Cr3+(1 mol∙dm-3) || Cℓ 2 (g) | Cℓ− (1 mol∙dm-3) | Pt(s) Accept/Aanvaar: Cr | Cr3+ || Cℓ 2 | Cℓ− | Pt (3) 8.3 OPTION 1/OPSIE 1 Notes/Aantekeninge θ E cell θ = E reduction θ − E oxidation  • Accept any other correct formula from the data   sheet./Aanvaar enige ander korrekte formule = 1,36 − ( −0,74) vanaf gegewensblad. θ E cell = 2,10 V  • Any other formula using unconventional abbreviations, e.g. E° cell = E° OA - E° RA followed by correct substitutions:/Enige ander formule wat onkonvensionele afkortings gebruik bv. E° sel = E° OM - E° RM gevolg deur korrekte vervangings : 3 4 OPTION 2/OPSIE 2 Cℓ 2 + 2e- → 2Cℓ− E θ = 1,36 V   Cr(s)  Cr3+(aq) + 3e- E θ = +0,74 V  2Cr(s) + 3Cℓ 2 (g) → 2Cr3+(aq) + 6Cℓ−(aq) E θ = +2,10 V  (4) 8.4 Increases/Verhoog  (2) [13] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 15 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 9/VRAAG 9 9.1 Electrolytic/Elektrolities  (1) 9.2 2H 2 O + 2e- → H 2 + 2OH-  Marking guidelines/Nasienriglyne • 2H 2 O + 2e- ⇌ H 2 + 2OH- 1 H 2 + 2OH- ⇌ 2H 2 O + 2e- 0 2 2 - H 2 + 2OH ← 2H 2 O + 2e - 2 - H 2 + 2OH → 2H 2 O + 2e - 0 2 2 • Ignore if charge omitted on electron./Ignoreer indien lading weggelaat op elektron. • If charge (-) omitted on OH-/Indien lading (-) weggelaat op OH-: Max./Maks: 1 - Example/Voorbeeld: 2H 2 O + 2e → H 2 + 2OH 2  (2) 9.3 9.3.1 Chlorine (gas) / Cℓ 2 /Chloor(gas)  (1) 9.3.2 P&Y (2) 9.4 Cathode/Katode  Reduction takes place here./Gains electrons. Reduksie vind hier plaas./Wins van elektrone. (2) 9.5 CuCℓ 2 (aq)  → Cu(s) + Cℓ 2 (g) Bal  OR/OF - Cu2+(aq) + 2Cℓ → Cu(s) + Cℓ 2 (g) Notes/Aantekeninge: • Reactants/Reaktanse  Products/Produkte  Balancing/Balansering  • Ignore double arrows./Ignoreer dubbelpyle. • Marking rule 6.3.10./Nasienreël 6.3.10. • Ignore phases/Ignoreer fases. (3) [11] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 16 DBE/2019 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 10/VRAAG 10 10.1 10.1.1 II – IV – III - I  (1) 10.1.2 2NH 3 + H 2 SO 4  → (NH 4 ) 2 SO 4  Bal  Notes/Aantekeninge: • Reactants/Reaktanse  Products/Produkte  Balancing/Balansering  • Ignore double arrows./Ignoreer dubbelpyle. • Marking rule 6.3.10./Nasienreël 6.3.10. (3) 10.1.3 Vanadium pentoxide/Vanadiumpentoksied  (1) 10.1.4 SO 3 (g) + H 2 SO 4 → H 2 S 2 O 7  Bal  Notes/Aantekeninge: • Reactants/Reaktanse  Products/Produkte  Balancing/Balansering  • Ignore double arrows./Ignoreer dubbelpyle. • Marking rule 6.3.10./Nasienreël 6.3.10. (3) 10.1.5 Sulphuric acid will form (white) mists./The reaction is very exothermic/gives off too much heat./Corrosive reaction.  Swawelsuur sal (wit) mis vorm./Die reaksie is té eksotermies/gee te veel warmte af./Vretende reaksie. (1) 10.2 Marking criteria/Nasienriglyne: • Calculate m(fertiliser)./Bereken m(kunsmis).  2 • Use ratio/gebruik verhouding: /m(P) = ½m(K)  X+3 • Use/Gebruik m(K) = 3,33 kg  • Final answer/Finale antwoord: 3  OPTION 1/OPSIE 1 OPTION 3/OPSIE 3 20 20 m(fertiliser) = × 50  (fertiliser) = × 50  100 100 = 10 kg = 10 kg 2 m(P) = ½m(K)  m(K) = × 10 = ½(3,33) = 1,665 kg X+3 2 ∴ 3,33  = × 10 m(X) = 10 – 3,33 – 1,665 X+3 = 5,005 ∴X=3 OPTION 2/OPSIE 2 N : P : K = 5,005 : 1,665 : 3,33 2  20 =3:1:2 m(K) = × x 50  = 3,33  X + 3 100 ∴X=3 X=3 (4) [13] TOTAL/TOTAAL: 150 Copyright reserved/Kopiereg voorbehou