OCR A Chemistry F322 Chains, Energy and Resources Thu 19 Jan 2012

oh that long question about forming atheromas? i wrote that LDLs (low density lipoproteins) are much unhealthier and increases the risk of atherosclerosis, they cause fatty depositions in the walls of coronary arteries, forming plaques and formation of atheroma, which restricts blood flow to cardiac muscle, and so prevents delivery of oxygen and nutrients. i wrote about phagocytes being attracted to the area as well, causing further deposition and increased risk of clots (thrombosis) (hope i didnt get confused with smoking)!! and that HDLs lower the risk of formation of atheromas, as cholesterol is transported from body tissues to liver. can't remember what else i wrote..i may be wrong!! :/

that is exactly what i wrote

Yayyyyy!!!

and for the water question ! i said acts as a solvent so ions attract to water molecules and said like uptake of ions such as maganesium , high melting point high specific heat capactiy , needs more energy to break bonds, ice is less dense than water so organims do not freeze , insulates under water , organism can swim .

Ok I've decided to produce a mark scheme because I.T revision is so f****ng boring. This is just my take on the answers...pretty certain most are correct but some might not be. If I've missed anything out I'd appreciate if you could add to it and amend any mistakes if you think otherwise. Apologies that questions are not in order. 

- Hydrocarbon as its a compound containing hydrogen and Carbon only, and saturated as no c=c/ carbon to carbon double bonds present.

- Empirical formula for cyclo.... CH2

-Structural isomers .. D and I..... One was straight one was brached

- Combustion of Heptane.... C7h16 + 1102 --> 7co2 +8h20

- The one where you had to state why one compound had a higher b.p than other was due to one having more Carbons in Chain/Longer chain length, hence More surface contact/points of interactions/surface interactions and more VdW forces, hence higher b.p

- Enthalpy change of formation is the enthalpy change that accompanies the formation of one mole of a compound from its constituent elements under standard con (25oc/1 atm/100KPa/298K)

- Functional group is an atom or group of atoms that give a compound its characteristic set of reactions.

- Reforming question.....C7H16 C7h14 +H2

- Cracking question.... C16H34 --> C8H18 + 2 C4H8

- Percentage yield question.. 93% apparently..


-Relative Atomic mass of metal to 1 dp.. 63.6 Metal: Copper

-Enthalpy cycle/Hess Cycle fill in the boxes....I am not sure on this one...I got -732... don’t know how

-Why are there still concerns about CFC’s? .....still being used.....long residency time...

-Show how CFC deplete ozone.... CFCl2 cfcl + cl

Cl +03ClO +02
ClO +002 +cl
Overall: 03 +0 202 hence ozone depleting.

-Why are scientists concern about the ozone? Depletion in ozone increase earths core temp and increase in harmful UV absorbed...which could lead to increase in incidence of skin cancer..

-Cfc’s are not chemically reactive....what else? Putting non-flammable as the answer wouldn’t be viable imo....it might but ideal answer for this one would be you can inhale them hence non toxic.

-Why wont Cfcl2 react in water....Absence of C-H bond/ Polar C-F and C-l cancel out/ No presence of OH/Hydroxyl group to form H-bonds in H20....leave this one up for debate

-Bond enthalpy question where it gave you table and you had to find enthalpy of H-Cl bond was 431.5

-For cyclopentene reacting with Cr207/h+ ,Br, and Nickel catalyst you had to draw ketone for first so cyclopentene with double bonded O coming off, for reaction with Br2 double bond eliminated and H Br replacing each H and for Nickel just cyclopentane fully saturated.

-Colour change that would occur when cyclopentene reacts with Br...Orange/brown to colourless/pale

-For the compound that using the Infared Spectroscopy chart (one with peaks)...Pentanal or Pentanone... either viable I believe

-For Carboxylic Acid it was 4 Carbons attatched to Carboxylic group (Butanoic Acid
)
-Question where you had to compare Process 1 production of Ester with process2....

Process 1 had higher Atom Economy..as only 1 product formed and various in Process 2 ( Dont think saying 99 per cent percentage yield is valid here..might be)

Process 1 used Methanol which I believe is renewable from sugar cane from plants whereas process 2 used ethane or something which was derived from crude oil hence finite and non renewable

Process 1 used lower pressure hence lower operational costs, saves energy and money and workers put under lower health risks.

-Question where you had to predict effect of pressure and temp on equilibrium increased temp bit was to the left because reaction is exothermic so if you increased the temp it would shift to decrease the temp in the endothermic direction pressure was also to the left because decrease in pressure pushed equilibrium to side with more gas molecules. Basically both moved left.

- How would higher pressure affect rate of reaction? ... rate of reaction increases as more particles per unit volume meaning more successfull collisions are likely to take place.

- Question where you had to predict effect of absence of catalyst on equilibrium... first bit was it would have no effect on equilibrium...second line under it was that absence of catalyst would slow down reverse reaction...(as catalyst speeds up both reverse and forward equally)

-Bond angles in CfCl2 ....109.5 Shape....Tetrahedral

-Q=Mc^T ..... first bit was 50x4.18x12.8=2675.2/1000
Second bit was mass over moles of Mg....which was 0.02
Final answer was 133.76....this is definitely wrong!!

-Structural Isomers of C8H17Cl was 4.......(96.3 Per cent confident that this is the answer hahahaha)


- For the structural Isomer question where you had to draw 2 steroisomers and one structural Isomer L and M (Stereoisomers) were Ch2-C2h5 and H H one either side of C=C bond so it was like C2H5---Ch3---C=C---H---H---- both cis and trans for L and M (Apologies if you don’t understand) and for the Strucutral Isomer it was C3H7----H—C=C---H---H



- Mass Spectrometry question.... M/z Peak was at 31+
- structure for peakwas Ch2OH/Ch3O
- Final structure( 46+) was C2H50H

- How cl bond splits by homolytic fission Cl2- Cl* +Cl* or 2Cl*

- Radical substitution question
- Initiation:
Cl2---> 2Cl*
propagation:
Cl* +h2 --> HCl +H*
H* +Cl2 --> HCL + CL*
Termination
CL* +H* --> HCl
Cl + Cl --> Cl2

- Boltzmann distribution...Labelled diagram with both Number of molecules/particles and Energy ....2 lines one T1 other t2....had to state at lower temp, less molecules have sufficient energy to overcome Ea, due to less frequent collisions due to less K.E. ORA I suppose.

- Question where you had to draw tertiary alchohol because it wouldn’t oxidise....basically it OH was attached to 3rd or 4th Carbon with other side of Carbon being attatched to methyl group...hence tertiary alchohol.

- Esters question- just had to draw structures really....Ethanoic Acid +Propanol ..... +H2O
Had to include water and state that OH from C.Acid and H from Alchohol....Also had to state under reflux and conc.H2SO4/H4P04

- For the question where you had to draw 2 repeat units for cyclopentene....basically

- The 2 substitution questions were pretty straight forward...cant demonstrate it on here anyway (sorry)


- Last Question... Heterolytic Fission and Nucleophillic Substitution

mate no need to worry that's perfectly correct! Good luck with all your exams! Take care!

Nice job, but I think the % yield was 94, not 93, as it asked for 2 sig figs.

I remember

As always lol

Ok I've decided to produce a mark scheme because I.T revision is so f****ng boring. This is just my take on the answers...pretty certain most are correct but some might not be. If I've missed anything out I'd appreciate if you could add to it and amend any mistakes if you think otherwise. Apologies that questions are not in order. 

- Hydrocarbon as its a compound containing hydrogen and Carbon only, and saturated as no c=c/ carbon to carbon double bonds present.

- Empirical formula for cyclo.... CH2

-Structural isomers .. D and I..... One was straight one was brached

- Combustion of Heptane.... C7h16 + 1102 --> 7co2 +8h20

- The one where you had to state why one compound had a higher b.p than other was due to one having more Carbons in Chain/Longer chain length, hence More surface contact/points of interactions/surface interactions and more VdW forces, hence higher b.p

- Enthalpy change of formation is the enthalpy change that accompanies the formation of one mole of a compound from its constituent elements under standard con (25oc/1 atm/100KPa/298K)

- Functional group is an atom or group of atoms that give a compound its characteristic set of reactions.

- Reforming question.....C7H16 C7h14 +H2

- Cracking question.... C16H34 --> C8H18 + 2 C4H8

- Percentage yield question.. 93% apparently..


-Relative Atomic mass of metal to 1 dp.. 63.6 Metal: Copper

-Enthalpy cycle/Hess Cycle fill in the boxes....I am not sure on this one...I got -732... don’t know how

-Why are there still concerns about CFC’s? .....still being used.....long residency time...

-Show how CFC deplete ozone.... CFCl2 cfcl + cl

Cl +03ClO +02
ClO +002 +cl
Overall: 03 +0 202 hence ozone depleting.

-Why are scientists concern about the ozone? Depletion in ozone increase earths core temp and increase in harmful UV absorbed...which could lead to increase in incidence of skin cancer..

-Cfc’s are not chemically reactive....what else? Putting non-flammable as the answer wouldn’t be viable imo....it might but ideal answer for this one would be you can inhale them hence non toxic.

-Why wont Cfcl2 react in water....Absence of C-H bond/ Polar C-F and C-l cancel out/ No presence of OH/Hydroxyl group to form H-bonds in H20....leave this one up for debate

-Bond enthalpy question where it gave you table and you had to find enthalpy of H-Cl bond was 431.5

-For cyclopentene reacting with Cr207/h+ ,Br, and Nickel catalyst you had to draw ketone for first so cyclopentene with double bonded O coming off, for reaction with Br2 double bond eliminated and H Br replacing each H and for Nickel just cyclopentane fully saturated.

-Colour change that would occur when cyclopentene reacts with Br...Orange/brown to colourless/pale

-For the compound that using the Infared Spectroscopy chart (one with peaks)...Pentanal or Pentanone... either viable I believe

-For Carboxylic Acid it was 4 Carbons attatched to Carboxylic group (Butanoic Acid
)
-Question where you had to compare Process 1 production of Ester with process2....

Process 1 had higher Atom Economy..as only 1 product formed and various in Process 2 ( Dont think saying 99 per cent percentage yield is valid here..might be)

Process 1 used Methanol which I believe is renewable from sugar cane from plants whereas process 2 used ethane or something which was derived from crude oil hence finite and non renewable

Process 1 used lower pressure hence lower operational costs, saves energy and money and workers put under lower health risks.

-Question where you had to predict effect of pressure and temp on equilibrium increased temp bit was to the left because reaction is exothermic so if you increased the temp it would shift to decrease the temp in the endothermic direction pressure was also to the left because decrease in pressure pushed equilibrium to side with more gas molecules. Basically both moved left.

- How would higher pressure affect rate of reaction? ... rate of reaction increases as more particles per unit volume meaning more successfull collisions are likely to take place.

- Question where you had to predict effect of absence of catalyst on equilibrium... first bit was it would have no effect on equilibrium...second line under it was that absence of catalyst would slow down reverse reaction...(as catalyst speeds up both reverse and forward equally)

-Bond angles in CfCl2 ....109.5 Shape....Tetrahedral

-Q=Mc^T ..... first bit was 50x4.18x12.8=2675.2/1000
Second bit was mass over moles of Mg....which was 0.02
Final answer was 133.76....this is definitely wrong!!

-Structural Isomers of C8H17Cl was 4.......(96.3 Per cent confident that this is the answer hahahaha)


- For the structural Isomer question where you had to draw 2 steroisomers and one structural Isomer L and M (Stereoisomers) were Ch2-C2h5 and H H one either side of C=C bond so it was like C2H5---Ch3---C=C---H---H---- both cis and trans for L and M (Apologies if you don’t understand) and for the Strucutral Isomer it was C3H7----H—C=C---H---H



- Mass Spectrometry question.... M/z Peak was at 31+
- structure for peakwas Ch2OH/Ch3O
- Final structure( 46+) was C2H50H

- How cl bond splits by homolytic fission Cl2- Cl* +Cl* or 2Cl*

- Radical substitution question
- Initiation:
Cl2---> 2Cl*
propagation:
Cl* +h2 --> HCl +H*
H* +Cl2 --> HCL + CL*
Termination
CL* +H* --> HCl
Cl + Cl --> Cl2

- Boltzmann distribution...Labelled diagram with both Number of molecules/particles and Energy ....2 lines one T1 other t2....had to state at lower temp, less molecules have sufficient energy to overcome Ea, due to less frequent collisions due to less K.E. ORA I suppose.

- Question where you had to draw tertiary alchohol because it wouldn’t oxidise....basically it OH was attached to 3rd or 4th Carbon with other side of Carbon being attatched to methyl group...hence tertiary alchohol.

- Esters question- just had to draw structures really....Ethanoic Acid +Propanol ..... +H2O
Had to include water and state that OH from C.Acid and H from Alchohol....Also had to state under reflux and conc.H2SO4/H4P04

- For the question where you had to draw 2 repeat units for cyclopentene....basically

- The 2 substitution questions were pretty straight forward...cant demonstrate it on here anyway (sorry)


- Last Question... Heterolytic Fission and Nucleophillic Substitution

uh for the structural isomer of I with the cl reaction wouldn't there be eight since the structure was something like ch3ch2ch(ch3)ch2ch2ch2ch3 which is not symmetrical? so it could fit on any of the 8 carbons to give a different strucutral isomer? therefore there are potentially 8 diffrent strucutral isomers?

uh for the structural isomer of I with the cl reaction wouldn't there be eight since the structure was something like ch3ch2ch(ch3)ch2ch2ch2ch3 which is not symmetrical? so it could fit on any of the 8 carbons to give a different strucutral isomer? therefore there are potentially 8 diffrent strucutral isomers?

LOL "Superdentist" you're probably correct..my bad.

hi can i ask for the question on three suggest why process 1 i said uses catalyst, higher atom economy and lower atomospheric pressure is it correct? thanks

for jan 2011 it was 72 and for june 2011 it was 76

Wait wait
So you can lose 25 marks and get an A?
Is the paper out of 100?! D:

-Why are scientists concern about the ozone? Depletion in ozone increase earths core temp and increase in harmful UV absorbed...which could lead to increase in incidence of skin cancer..

DAMN IT SKIN CANCER ...

I put global warming ... That correct too?

No sadly

But google says so too