AQA A Level Chemistry Paper 3 20th June 2018 Unofficial Markscheme
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Original post by Sweetie08
i did that as i was sure it wasn't any of the other ones but still dont know how its a base
it accepts a proton from the sulfuric acid. It wasn't immediately obvious from the overall equation they gave you, but do you recall the first of the two steps for forming the electrophile in nitration of benzene-
HNO₃ + H₂SO4 --> HSO₄ (-) + H₂NO₃ (+)
you can see in that equation that sulfuric acid donates a proton to the nitric acid
Original post by LunaCat
Ion that won't catalyse reaction if I- etc, Fe3+?
i got cr3+ i think
-33.6 kjmol-1
0.0012?moldm-3s-1
0.0004 ish as rate
76%
9.5% uncertainty, decrease uncertainty but increasing concs of acid and alkali so greater temp change
Lower pressure + higher temp
Entropy change large and positive
Largest mass of ppt was the one where both baso4 and mg(oh)2 formed
Na + O₂ = yellow flame and white smoke. P4 + O₂ white smoke
Aluminium highest melting point
Bromophenl blue indicator
Decolorises bromone water
Sodium carbonate removes H+ left from phosphoric acid
Open tap to prevent build up of CO₂
On one multiple choice question it was choosing which reaction can occur and I put the elimination one with the KOH
Lithium iodide has most covalent character
Rate equation [X][Y]
Does anyone remember anymore multiple choice questions?
0.0012?moldm-3s-1
0.0004 ish as rate
76%
9.5% uncertainty, decrease uncertainty but increasing concs of acid and alkali so greater temp change
Lower pressure + higher temp
Entropy change large and positive
Largest mass of ppt was the one where both baso4 and mg(oh)2 formed
Na + O₂ = yellow flame and white smoke. P4 + O₂ white smoke
Aluminium highest melting point
Bromophenl blue indicator
Decolorises bromone water
Sodium carbonate removes H+ left from phosphoric acid
Open tap to prevent build up of CO₂
On one multiple choice question it was choosing which reaction can occur and I put the elimination one with the KOH
Lithium iodide has most covalent character
Rate equation [X][Y]
Does anyone remember anymore multiple choice questions?
Original post by Lalalozzaland
Was it me or was one of the multiple choice questions wrong. It was the ligand substitution one, it asked for which one was correct but I thought 3 of them seemed correct and one was incorrect?
What metal was it?
Original post by london256145
yeahhhh
25cm3 and 75cm3 so a total of 100cm3. density is 1 so mass is 100gram
using Q=mcdelta t .... 100 x 3.2 x 4.2 = 1344 joules = -1.344 kilojoules (negative as its exothermic) ...
0.02 mols of acid and 0.045 mols of KOH so using balance symbol equation 0.04 mols of KOH reacted with 0.02 mols of acid (0.005 mols of KOH in excess. mole ratio of KOH:h20 was 2:2 or ratio of acid:h20 is 1:2 so 0.04 moles of h2o
divide -1.344 by 0.04 to get -336kjmol-1 hope that helps and makes sense
if I got the temperature change wrong but worked out percentage uncertainty right with my value do I get a follow through mark?
Original post by LunaCat
CsF for the one that has the biggest difference between born haber and date book?
I did LiI
Original post by LunaCat
Ion that won't catalyse reaction if I- etc, Fe3+?
I put cr2+ as its the only one with a electrode potential lower than both the half equations therefore it will reduce both completely
y 2drquadrule
i put rate [w]2[y] because if you double it rate will quadruple. conc of catalyst doesnt affect rate. would doubling x just increase rate by 2 as its first order?
Original post by brendonurine
-33.6 kjmol-1
0.0012?moldm-3s-1
0.0004 ish as rate
76%
9.5% uncertainty, decrease uncertainty but increasing concs of acid and alkali so greater temp change
Lower pressure + higher temp
Entropy change large and positive
Largest mass of ppt was the one where both baso4 and mg(oh)2 formed
Na + O₂ = yellow flame and white smoke. P4 + O₂ white smoke
Aluminium highest melting point
Bromophenl blue indicator
Decolorises bromone water
Sodium carbonate removes H+ left from phosphoric acid
Open tap to prevent build up of CO₂
On one multiple choice question it was choosing which reaction can occur and I put the elimination one with the KOH
Lithium iodide has most covalent character
Rate equation [X][Y]
Does anyone remember anymore multiple choice questions?
0.0012?moldm-3s-1
0.0004 ish as rate
76%
9.5% uncertainty, decrease uncertainty but increasing concs of acid and alkali so greater temp change
Lower pressure + higher temp
Entropy change large and positive
Largest mass of ppt was the one where both baso4 and mg(oh)2 formed
Na + O₂ = yellow flame and white smoke. P4 + O₂ white smoke
Aluminium highest melting point
Bromophenl blue indicator
Decolorises bromone water
Sodium carbonate removes H+ left from phosphoric acid
Open tap to prevent build up of CO₂
On one multiple choice question it was choosing which reaction can occur and I put the elimination one with the KOH
Lithium iodide has most covalent character
Rate equation [X][Y]
Does anyone remember anymore multiple choice questions?
i put rate [w]2[y] because if you double it rate will quadruple. conc of catalyst doesnt affect rate. would doubling x just increase rate by 2 as its first order?
Original post by Hdheimdnbf
What was the actual temp for the 4th minute
I got 25 degrees
Original post by Hdheimdnbf
What was the actual temp for the 4th minute
I think it was around 21.9 and the change was 2.1 but I kept messing up the scale so i think my value is wrong.
Original post by Blos
I got 25 degrees
So temp change was?..
Original post by Jadejay
How did you do it? I got -21 but I don’t think it was right
i did q=mcdeltaT and got 116kj
then did -116 divided by moles of water
-Why was sodium carbonate added?
To react with the acid so that it can be removed ( and produced isolated)
-Why was the separating funnel opened now and then after invertion?
To let any gas that had been produced (by the reaction above) such as CO2
Or else glass could break
-how is melting point measured, how to know it contained impurities?
Fill 0. 5cm of powder if capillary tube
Place in meting point apparatus with thermometer attached
Increase temp slowly until powder has melted and rises up the tube
record temp
if lower than what data book says, then contained impurities
To react with the acid so that it can be removed ( and produced isolated)
-Why was the separating funnel opened now and then after invertion?
To let any gas that had been produced (by the reaction above) such as CO2
Or else glass could break
-how is melting point measured, how to know it contained impurities?
Fill 0. 5cm of powder if capillary tube
Place in meting point apparatus with thermometer attached
Increase temp slowly until powder has melted and rises up the tube
record temp
if lower than what data book says, then contained impurities
1.1 Explain...rate of reaction depends only on H+ Conc (2)
1.2 What's done to each sample before titrated (2)
1.3 Explain...how graph shows order (2)
1.4 Calculate k1 and give units (3)
1.5 Plot results (1)
1.6 Draw line of best fit (1)
1.7 Calculate rate of reaction when H+ is 0.35 (2)
1.8 Explain...series of experiments (6)
2.1 Sodium heated in Oxygen: Equation, Obs 1, Obs 2 (2)
2.2 Phosphorus and Oxygen: Equation, Obs 1 (2)
2.3 Explain....increase in MP from Sodium Oxide to Mg Oxide (2)
2.4 Explain....MP of oxide silicon higher than oxide of P (3)
2.5 Describe....method for MP and how result for purity (3)
3.1 % yield of cyclohexane (3)
3.2 Describe...test-tube reaction for cyclohexanol dehydrated. Observer what? (2)
3.3 Why Sodium carbonate used to wash (1)
3.4 Important to open tap periodically (1)
3.5 Property of annhydrous calcium chloride (1)
3.6 Describe apparatus used to remove drying agent under reduced pressure (2)
3.7 Explain....why cyclohexene has shorter retention time than cyclohexanol (2)
3.8 Explain....infrared spectrum cyclohexene from chromotography did not contain cyclohexanol (1)
4.1 Temperature at 4th minute (5)
4.2 Percentage uncertainty (1)
4.3 Suggest change to minimise heat loss (1)
4.4 Suggest another change to decrease uncertainty (2)
4.5 Equation between ethanedioic acid (25 cm3 0.80 moldm-3) and KOH (75 cm3 0.60 moldm-3) . Temp increase by 3.2. Calculate enthalphy change (5)
4.6 Suggest explanation for difference between -57kJ mol-1 and answer in 4.5 (2)
5. Both empirical and molecular (A: CH2O B: P4O10 C: NH2 D: CH3)
6. Correct bonding and bond polarity
7. He2+ particles (A: Gold atoms contain electrons B: Protons C: Neutrons D: Empty space)
8. Conclusion drawn Gold atoms have (A: small nucleus B: electrons in orbital C: ions in sea of e- D: more protons than He2+)
9. Termination step
10. Correct statement (A: HBr eletrophilic B: NaBH4 nucleophili addition-elimination C: KOH elimination D: KCN nucleophilic
11. Correct for 2-methylbutan 1 and 2-ol (A: formed by esters B: oxidised by reaction C: formed by hydration of 2-methylbut-2-ene D: four peaks)
12. Rate equation (A: k[w]2[x] B: k[w]2[y] C: k[x][y] D: k[x][z]
13. Graph with respect to conc of x
14. Atomisation of iodine (A: 1/2I2(s) - I B: I2(s) - 2I C: 1/2I2(g) - I D: I2(g) - 2I)
15. Structure formed by aspartic acid
16. Peaks in 1-4 dimethylbenzene (A: 8 B: 4 C: 3 D: 2)
17. Highest MP (A: Al B: P C: Na D: S)
18. List of products (A: Sodium chloride, chlorate(I) and water B: Chlorate(I) and water C: Chloride, chlorate (V) and water D: Chloride and chlorate(I) )
19. Magnesium and steam (A: hydroxide and hydrogen B: hydroxide and oxygen C: oxide and hydrogen D: oxide and oxygen)
20: Observation (A: litmus paper red when touched B: paper blue when touched C: paper when when held above D: paper blue when held above)
21. Repeating unit of polymer pairs
22. Structure of polyester soften at high temp (A: h bonds and van der waals B: dipole-dipole and van der waals C: carbon-carbon strong D: carbox-oxygen bonds)
23. Correct statement (A: HNO3 base B: catalyst C: electrophile D: reducing agent)
24. correct order of pH (A: am > eth > phe B: amm > phe > eth C: eth > amm > phe D: eth > phe > amm)
25. Ionic oxide strong alkalis (A: Al B: Mg C: Na D: S)
26. Correct statement (A: coordination no. decreases of cobalt B: Enthalpy change large and +ve C: entropy change large D: Shape of complex changes)
27. Which complex optical isomer
28. How many structural isomers react with tollens (A: 3 B: 4 C: 5 D: 6)
29. WHich ion cannot catalyse (A: Co2+ B: Cr2+ C: Fe2+ D@ Fe3+)
30. Shape influenced by presence of lone pairs (A: AlCl3 B: ClF3 C: IF6+ D: PCl6-)
31. Greatest mass of solid Ba(OH)2 and (A: MgCl2 B: MgSO4 C: NaCl D: Na2SO4)
32. Which indicator methylamine (A: Thymol blue B: Bromophenol blue C: Phenol red D: Phenolphthalein)
33. Compound greatest percentage difference (A: CsF B: CsI C: LiF D: LiI)
34. Greatest equilibrium yield (A: high pr and high temp B: High pres and low temp C: low pres and high temp D: low pres and low temp)
Can you help out guys @Bulletzone @Tommy59375 ?
1.2 What's done to each sample before titrated (2)
1.3 Explain...how graph shows order (2)
1.4 Calculate k1 and give units (3)
1.5 Plot results (1)
1.6 Draw line of best fit (1)
1.7 Calculate rate of reaction when H+ is 0.35 (2)
1.8 Explain...series of experiments (6)
2.1 Sodium heated in Oxygen: Equation, Obs 1, Obs 2 (2)
2.2 Phosphorus and Oxygen: Equation, Obs 1 (2)
2.3 Explain....increase in MP from Sodium Oxide to Mg Oxide (2)
2.4 Explain....MP of oxide silicon higher than oxide of P (3)
2.5 Describe....method for MP and how result for purity (3)
3.1 % yield of cyclohexane (3)
3.2 Describe...test-tube reaction for cyclohexanol dehydrated. Observer what? (2)
3.3 Why Sodium carbonate used to wash (1)
3.4 Important to open tap periodically (1)
3.5 Property of annhydrous calcium chloride (1)
3.6 Describe apparatus used to remove drying agent under reduced pressure (2)
3.7 Explain....why cyclohexene has shorter retention time than cyclohexanol (2)
3.8 Explain....infrared spectrum cyclohexene from chromotography did not contain cyclohexanol (1)
4.1 Temperature at 4th minute (5)
4.2 Percentage uncertainty (1)
4.3 Suggest change to minimise heat loss (1)
4.4 Suggest another change to decrease uncertainty (2)
4.5 Equation between ethanedioic acid (25 cm3 0.80 moldm-3) and KOH (75 cm3 0.60 moldm-3) . Temp increase by 3.2. Calculate enthalphy change (5)
4.6 Suggest explanation for difference between -57kJ mol-1 and answer in 4.5 (2)
5. Both empirical and molecular (A: CH2O B: P4O10 C: NH2 D: CH3)
6. Correct bonding and bond polarity
7. He2+ particles (A: Gold atoms contain electrons B: Protons C: Neutrons D: Empty space)
8. Conclusion drawn Gold atoms have (A: small nucleus B: electrons in orbital C: ions in sea of e- D: more protons than He2+)
9. Termination step
10. Correct statement (A: HBr eletrophilic B: NaBH4 nucleophili addition-elimination C: KOH elimination D: KCN nucleophilic
11. Correct for 2-methylbutan 1 and 2-ol (A: formed by esters B: oxidised by reaction C: formed by hydration of 2-methylbut-2-ene D: four peaks)
12. Rate equation (A: k[w]2[x] B: k[w]2[y] C: k[x][y] D: k[x][z]
13. Graph with respect to conc of x
14. Atomisation of iodine (A: 1/2I2(s) - I B: I2(s) - 2I C: 1/2I2(g) - I D: I2(g) - 2I)
15. Structure formed by aspartic acid
16. Peaks in 1-4 dimethylbenzene (A: 8 B: 4 C: 3 D: 2)
17. Highest MP (A: Al B: P C: Na D: S)
18. List of products (A: Sodium chloride, chlorate(I) and water B: Chlorate(I) and water C: Chloride, chlorate (V) and water D: Chloride and chlorate(I) )
19. Magnesium and steam (A: hydroxide and hydrogen B: hydroxide and oxygen C: oxide and hydrogen D: oxide and oxygen)
20: Observation (A: litmus paper red when touched B: paper blue when touched C: paper when when held above D: paper blue when held above)
21. Repeating unit of polymer pairs
22. Structure of polyester soften at high temp (A: h bonds and van der waals B: dipole-dipole and van der waals C: carbon-carbon strong D: carbox-oxygen bonds)
23. Correct statement (A: HNO3 base B: catalyst C: electrophile D: reducing agent)
24. correct order of pH (A: am > eth > phe B: amm > phe > eth C: eth > amm > phe D: eth > phe > amm)
25. Ionic oxide strong alkalis (A: Al B: Mg C: Na D: S)
26. Correct statement (A: coordination no. decreases of cobalt B: Enthalpy change large and +ve C: entropy change large D: Shape of complex changes)
27. Which complex optical isomer
28. How many structural isomers react with tollens (A: 3 B: 4 C: 5 D: 6)
29. WHich ion cannot catalyse (A: Co2+ B: Cr2+ C: Fe2+ D@ Fe3+)
30. Shape influenced by presence of lone pairs (A: AlCl3 B: ClF3 C: IF6+ D: PCl6-)
31. Greatest mass of solid Ba(OH)2 and (A: MgCl2 B: MgSO4 C: NaCl D: Na2SO4)
32. Which indicator methylamine (A: Thymol blue B: Bromophenol blue C: Phenol red D: Phenolphthalein)
33. Compound greatest percentage difference (A: CsF B: CsI C: LiF D: LiI)
34. Greatest equilibrium yield (A: high pr and high temp B: High pres and low temp C: low pres and high temp D: low pres and low temp)
Can you help out guys @Bulletzone @Tommy59375 ?
Original post by Vetahanj
I think it was around 21.9 and the change was 2.1 but I kept messing up the scale so i think my value is wrong.
I got 2.1 too
Original post by Lalalozzaland
Was it me or was one of the multiple choice questions wrong. It was the ligand substitution one, it asked for which one was correct but I thought 3 of them seemed correct and one was incorrect?
I thought this as well !!
For multiple choice: the gold atom has lots of empty space and gold has orbitals
1.1 Explain...rate of reaction depends only on H+ Conc (2)
1.2 What's done to each sample before titrated (2)
1.3 Explain...how graph shows order (2)
1.4 Calculate k1 and give units (3)
1.5 Plot results (1)
Unless you can't count you'll probably get a mark.
1.6 Draw line of best fit (1)
The line of best fit shall vary quite a bit as there was a weak correlation.
1.7 Calculate rate of reaction when H+ is 0.35 (2)
0.35 / (Time for your line of best fit)
1.8 Explain...series of experiments (6)
Cba
2.1 Sodium heated in Oxygen: Equation, Obs 1, Obs 2 (2)
4Na + O2 --------> 2Na2O (allow multiples) Yellow Glow and White solid produced
2.2 Phosphorus and Oxygen: Equation, Obs 1 (2)
P4 + 5O2 ------> P4O10 (Allow: 4P + 5O2 -----> P4O10) and White smoke
2.3 Explain....increase in MP from Sodium Oxide to Mg Oxide (2)
Magnesium has a higher charge density
so
Stronger electrostatic forces of attraction between the Mg2+ and O2- Ions.
Therefore more energy required to break the stronger ionic bond hence higher Melting point.
2.4 Explain....MP of oxide silicon higher than oxide of P (3)
Silicon Dioxide is a macromolecule.
It has Many strong covalent bonds (You need "many" for a mark)
Lots of energy needed to break the bonds.
P4O10 only has weaker Intermolecular forces between the molecules (van der waals forces), these are much weaker than the covalent bonds so less energy needed to break.
2.5 Describe....method for MP and how result for purity (3)
Capillary tube.
Small amount inside.
Place inside a melting point machine with a thermometer.
Heat and it shall melt sharply at melting point.
If pure when compared to Data booklet of known Melting point they should be the same. If not the same then impurities are present.
3.1 % yield of cyclohexane (3)
70-something percent
3.2 Describe...test-tube reaction for cyclohexanol dehydrated. Observer what? (2)
Add bromine water.
Bromine water shall go from orange to colourless
3.3 Why Sodium carbonate used to wash (1)
Removes excess acid on surface of cyclohexene.
3.4 Important to open tap periodically (1)
Release the CO2 gas that is produced to prevent explosion.
3.5 Property of annhydrous calcium chloride (1)
Does not react with the product.
3.6 Describe apparatus used to remove drying agent under reduced pressure (2)
Draw a typical filter setup with an opening to Vacuum pump and fluted filter paper.
3.7 Explain....why cyclohexene has shorter retention time than cyclohexanol (2)
Cyclohexanol is more polar therefore it is more attracted/affinity to the silica (stationary phase) therefore takes longer to come out (Unsure about this)
3.8 Explain....infrared spectrum cyclohexene from chromotography did not contain cyclohexanol (1)
Contains C=C bond so shall have a peak at 1620-1680cm-1 (This may be wrong, quoting off memory)
4.1 Temperature at 4th minute (5)
Forgot
4.2 Percentage uncertainty (1)
Forgot
4.3 Suggest change to minimise heat loss (1)
Add a lid
4.4 Suggest another change to decrease uncertainty (2)
Need to increase the temperature change so have more concentrated reagents.
4.5 Equation between ethanedioic acid (25 cm3 0.80 moldm-3) and KOH (75 cm3 0.60 moldm-3) . Temp increase by 3.2. Calculate enthalphy change (5)
4.6 Suggest explanation for difference between -57kJ mol-1 and answer in 4.5 (2)
5. Both empirical and molecular (A: CH2O B: P4O10 C: NH2 D: CH3)
A
6. Correct bonding and bond polarity
7. He2+ particles (A: Gold atoms contain electrons B: Protons C: Neutrons D: Empty space)
D
8. Conclusion drawn Gold atoms have (A: small nucleus B: electrons in orbital C: ions in sea of e- D: more protons than He2+)
A
9. Termination step
10. Correct statement (A: HBr eletrophilic B: NaBH4 nucleophili addition-elimination C: KOH elimination D: KCN nucleophilic
C
11. Correct for 2-methylbutan 1 and 2-ol (A: formed by esters B: oxidised by reaction C: formed by hydration of 2-methylbut-2-ene D: four peaks)
A
12. Rate equation (A: k[w]2[x] B: k[w]2[y] C: k[x][y] D: k[x][z]
Forgot lol
13. Graph with respect to conc of x
D It was curve that slopped upwards
14. Atomisation of iodine (A: 1/2I2(s) - I B: I2(s) - 2I C: 1/2I2(g) - I D: I2(g) - 2I)
A
15. Structure formed by aspartic acid
I think it was C but both COOH lost their Hydrogens
16. Peaks in 1-4 dimethylbenzene (A: 8 B: 4 C: 3 D: 2)
C
17. Highest MP (A: Al B: P C: Na D: S)
A
18. List of products (A: Sodium chloride, chlorate(I) and water B: Chlorate(I) and water C: Chloride, chlorate (V) and water D: Chloride and chlorate(I) )
A
19. Magnesium and steam (A: hydroxide and hydrogen B: hydroxide and oxygen C: oxide and hydrogen D: oxide and oxygen)
C
20: Observation (A: litmus paper red when touched B: paper blue when touched C: paper when when held above D: paper blue when held above)
21. Repeating unit of polymer pairs
It was C or B i think
22. Structure of polyester soften at high temp (A: h bonds and van der waals B: dipole-dipole and van der waals C: carbon-carbon strong D: carbox-oxygen bonds)
B
23. Correct statement (A: HNO3 base B: catalyst C: electrophile D: reducing agent)
A
24. correct order of pH (A: am > eth > phe B: amm > phe > eth C: eth > amm > phe D: eth > phe > amm)
C
25. Ionic oxide strong alkalis (A: Al B: Mg C: Na D: S)
D
26. Correct statement (A: coordination no. decreases of cobalt B: Enthalpy change large and +ve C: entropy change large D: Shape of complex changes)
27. Which complex optical isomer
[Cu(NH3)4(H2O)2]2+
28. How many structural isomers react with tollens (A: 3 B: 4 C: 5 D: 6)
Forgot what I put, I think I put B
29. WHich ion cannot catalyse (A: Co2+ B: Cr2+ C: Fe2+ D@ Fe3+)
B
30. Shape influenced by presence of lone pairs (A: AlCl3 B: ClF3 C: IF6+ D: PCl6-)
B ?
31. Greatest mass of solid Ba(OH)2 and (A: MgCl2 B: MgSO4 C: NaCl D: Na2SO4)
You needed the one with the smallest Mr so NaCl
32. Which indicator methylamine (A: Thymol blue B: Bromophenol blue C: Phenol red D: Phenolphthalein)
Thymol Blue
33. Compound greatest percentage difference (A: CsF B: CsI C: LiF D: LiI)
LiF
34. Greatest equilibrium yield (A: high pr and high temp B: High pres and low temp C: low pres and high temp D: low pres and low temp)
1.2 What's done to each sample before titrated (2)
1.3 Explain...how graph shows order (2)
1.4 Calculate k1 and give units (3)
1.5 Plot results (1)
Unless you can't count you'll probably get a mark.
1.6 Draw line of best fit (1)
The line of best fit shall vary quite a bit as there was a weak correlation.
1.7 Calculate rate of reaction when H+ is 0.35 (2)
0.35 / (Time for your line of best fit)
1.8 Explain...series of experiments (6)
Cba
2.1 Sodium heated in Oxygen: Equation, Obs 1, Obs 2 (2)
4Na + O2 --------> 2Na2O (allow multiples) Yellow Glow and White solid produced
2.2 Phosphorus and Oxygen: Equation, Obs 1 (2)
P4 + 5O2 ------> P4O10 (Allow: 4P + 5O2 -----> P4O10) and White smoke
2.3 Explain....increase in MP from Sodium Oxide to Mg Oxide (2)
Magnesium has a higher charge density
so
Stronger electrostatic forces of attraction between the Mg2+ and O2- Ions.
Therefore more energy required to break the stronger ionic bond hence higher Melting point.
2.4 Explain....MP of oxide silicon higher than oxide of P (3)
Silicon Dioxide is a macromolecule.
It has Many strong covalent bonds (You need "many" for a mark)
Lots of energy needed to break the bonds.
P4O10 only has weaker Intermolecular forces between the molecules (van der waals forces), these are much weaker than the covalent bonds so less energy needed to break.
2.5 Describe....method for MP and how result for purity (3)
Capillary tube.
Small amount inside.
Place inside a melting point machine with a thermometer.
Heat and it shall melt sharply at melting point.
If pure when compared to Data booklet of known Melting point they should be the same. If not the same then impurities are present.
3.1 % yield of cyclohexane (3)
70-something percent
3.2 Describe...test-tube reaction for cyclohexanol dehydrated. Observer what? (2)
Add bromine water.
Bromine water shall go from orange to colourless
3.3 Why Sodium carbonate used to wash (1)
Removes excess acid on surface of cyclohexene.
3.4 Important to open tap periodically (1)
Release the CO2 gas that is produced to prevent explosion.
3.5 Property of annhydrous calcium chloride (1)
Does not react with the product.
3.6 Describe apparatus used to remove drying agent under reduced pressure (2)
Draw a typical filter setup with an opening to Vacuum pump and fluted filter paper.
3.7 Explain....why cyclohexene has shorter retention time than cyclohexanol (2)
Cyclohexanol is more polar therefore it is more attracted/affinity to the silica (stationary phase) therefore takes longer to come out (Unsure about this)
3.8 Explain....infrared spectrum cyclohexene from chromotography did not contain cyclohexanol (1)
Contains C=C bond so shall have a peak at 1620-1680cm-1 (This may be wrong, quoting off memory)
4.1 Temperature at 4th minute (5)
Forgot
4.2 Percentage uncertainty (1)
Forgot
4.3 Suggest change to minimise heat loss (1)
Add a lid
4.4 Suggest another change to decrease uncertainty (2)
Need to increase the temperature change so have more concentrated reagents.
4.5 Equation between ethanedioic acid (25 cm3 0.80 moldm-3) and KOH (75 cm3 0.60 moldm-3) . Temp increase by 3.2. Calculate enthalphy change (5)
4.6 Suggest explanation for difference between -57kJ mol-1 and answer in 4.5 (2)
5. Both empirical and molecular (A: CH2O B: P4O10 C: NH2 D: CH3)
A
6. Correct bonding and bond polarity
7. He2+ particles (A: Gold atoms contain electrons B: Protons C: Neutrons D: Empty space)
D
8. Conclusion drawn Gold atoms have (A: small nucleus B: electrons in orbital C: ions in sea of e- D: more protons than He2+)
A
9. Termination step
10. Correct statement (A: HBr eletrophilic B: NaBH4 nucleophili addition-elimination C: KOH elimination D: KCN nucleophilic
C
11. Correct for 2-methylbutan 1 and 2-ol (A: formed by esters B: oxidised by reaction C: formed by hydration of 2-methylbut-2-ene D: four peaks)
A
12. Rate equation (A: k[w]2[x] B: k[w]2[y] C: k[x][y] D: k[x][z]
Forgot lol
13. Graph with respect to conc of x
D It was curve that slopped upwards
14. Atomisation of iodine (A: 1/2I2(s) - I B: I2(s) - 2I C: 1/2I2(g) - I D: I2(g) - 2I)
A
15. Structure formed by aspartic acid
I think it was C but both COOH lost their Hydrogens
16. Peaks in 1-4 dimethylbenzene (A: 8 B: 4 C: 3 D: 2)
C
17. Highest MP (A: Al B: P C: Na D: S)
A
18. List of products (A: Sodium chloride, chlorate(I) and water B: Chlorate(I) and water C: Chloride, chlorate (V) and water D: Chloride and chlorate(I) )
A
19. Magnesium and steam (A: hydroxide and hydrogen B: hydroxide and oxygen C: oxide and hydrogen D: oxide and oxygen)
C
20: Observation (A: litmus paper red when touched B: paper blue when touched C: paper when when held above D: paper blue when held above)
21. Repeating unit of polymer pairs
It was C or B i think
22. Structure of polyester soften at high temp (A: h bonds and van der waals B: dipole-dipole and van der waals C: carbon-carbon strong D: carbox-oxygen bonds)
B
23. Correct statement (A: HNO3 base B: catalyst C: electrophile D: reducing agent)
A
24. correct order of pH (A: am > eth > phe B: amm > phe > eth C: eth > amm > phe D: eth > phe > amm)
C
25. Ionic oxide strong alkalis (A: Al B: Mg C: Na D: S)
D
26. Correct statement (A: coordination no. decreases of cobalt B: Enthalpy change large and +ve C: entropy change large D: Shape of complex changes)
27. Which complex optical isomer
[Cu(NH3)4(H2O)2]2+
28. How many structural isomers react with tollens (A: 3 B: 4 C: 5 D: 6)
Forgot what I put, I think I put B
29. WHich ion cannot catalyse (A: Co2+ B: Cr2+ C: Fe2+ D@ Fe3+)
B
30. Shape influenced by presence of lone pairs (A: AlCl3 B: ClF3 C: IF6+ D: PCl6-)
B ?
31. Greatest mass of solid Ba(OH)2 and (A: MgCl2 B: MgSO4 C: NaCl D: Na2SO4)
You needed the one with the smallest Mr so NaCl
32. Which indicator methylamine (A: Thymol blue B: Bromophenol blue C: Phenol red D: Phenolphthalein)
Thymol Blue
33. Compound greatest percentage difference (A: CsF B: CsI C: LiF D: LiI)
LiF
34. Greatest equilibrium yield (A: high pr and high temp B: High pres and low temp C: low pres and high temp D: low pres and low temp)
(edited 5 years ago)
dr
draw tangent at t=0 and find gradient
Original post by Lalalozzaland
How did everyone put to find initial rate in the 6 marker!? I put 1/time
draw tangent at t=0 and find gradient
Quick Reply
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