OCR Chemistry F322~ 4th June 2013~ AS Chemistry

You know where it had the energy profile diagram drawn, and it asked for enthalpy change when 240 dm^3 is formed, did you have to times by 5 or 10?

Posted from TSR Mobile

Oh good! I was doubting myself for a minute !!

Hey you know the equilibrium question? Did you put left and left or left and right or what.

I can't even remember . I think I counted the moles wrong for the pressure. Damn


Posted from TSR Mobile

By 5

Was the colour change orange to green or colourless?

Was I the only one that didnt come out of that feeling confident? I didnt find it difficult as such, but what the questions where trying to get at sometimes was not obvious, did anyone else feel that??

Omg.... I did that and then I thought it says per mole by the number, so it should be by 10... And I changed it....

Posted from TSR Mobile

A SORT OF UNNOFFICIAL MARK-SChEME (MAY BE OUT OF ORDER)

First Question
- C10H22
- (drawn) any branched isomer of c10h22 AND named [ i put 2-methylnonane ]
- (cracking question) C15H31 ----> C10H20 + C5H12 (any suitable equation-
- why does cracking hydrocarbons produce many products? C-C bond can break anywhere in the hydrocarbon chain
- (drawn) cyclo-octane i drew both skeletal and displayed formula of this just in case
- cyclo-alkanes are made because they burn more efficiently/ have a higher octane rating

Other question answers :
- homologous series: molecules that have same functional group but each successive member differs by a CH2
- burns with black smoke due to imcomplete combustion/ black smoke and yellow flame indicates there was a lack of oxygen therefore it did not combust completely.
- [question about why does something have 100% atom economy] because there was only 1 product produced in the reaction/ no waste products were produced in the reaction

Question about weird looking molecule thing showing E/z isomerism:
- functional groups present were an ester and an alkene (c-c double bond and a c-o double bond o)
- structure j is different from structure i because in I both the groups are on the same side of the double bond (Z isomerism) whereas in J each group is on the different sides of the c-c double bond (E isomerism)
Box Drawings for products of Alcohol when
1-oxidised
2-reacted with a carboxylic acid
3-dehydrated/hydrated


For the question about halogenoalkanes:
- most unreactive: i put the first one (N)
- Most reactive one had 2 halogens in it (I and Br)

- P had a lower b/p than Q because P contained Br and Q contained I. The C-I bond is longer than the C-Br bond, thus it is easier to overcome the C-I bond as it experiences less attraction to the nucleus of the C atom/ takes less energy to overcome C-I bond.

Had to choose one of the halogenoalkanes to demonstrate electrophilic addition (1) + diagram

For the Le chatelier question:
increasing temp: favours reverse reaction/position shifts to reduce temp, backward reaction endothermic
Increasing pressure: favors forward reaction, position of equilibrium moves right/less molecules on right hand side
removing catalyst: does not affect position of equilibrium
[not too sure about these^]

Define stereo isomers: have the same structural and molecular formula but different 3D arrangements of atoms in space


graph with percentages : 195.6 (approx) of something to 1 dp

i got 96.9% as the yield of something to do with propene (i cant remember)

got something like 4956 (approx) for the hess cycle question

4.96 X10-3 moles (of something cant remember again lol)

820 kjmol-1 as the enthalpy change when 230dm^3 is produces from N2 and O2

82 kJ as the next answer

on the mass spec

For yeast question:
C6h12o6 ---> c2h50h + h20 (i forgot to balance do i lose a mark?)

CFCs - biodegradable alternatives:
i wrote HCFCs because i had NO idea, anybody know the answer?

Mass spec of Sulphur
M+ was the value of the furthest line to the right
S8
the m/z was the base (tallest) peak
S4+

free radical question:
Initiation: IBr ---> I* + Br* (in presence of UV)
Propagation 1 : Ch4 + Br* ---> Ch3* + HBr
Propagation 2: ch3* + IBr ----> CH3I + Br*


for propaation 2 i wrote Ch3* + I* -----> CH3I (but its wrong because its a termination step ! silly me!!!)


Termination step (any two radicals added)

The bond fission was homolytic (because 1 e- from the covalent bond goes to each atom)

Working out the X and Y substances from the IR spec:
empirical formula gave c4h8O
i got that it could be an aldehyde or a ketone (due to absorbtions stated)
i drew the aldehyde and ketone structure but didnt name them, will i lose a mark?

For the bolztman distribution:
temp: 2 curves, one lower than the other
increasing temp1 increases the mean energy of the particles therefore particles collide more and have more successful collisions

catalyst: 1 curve, 2 activation energy lines shown
adding a catalyst reduces the activation energy meaning more particles have the sufficient energy required to overcome the energy barrier to react. thus a greater rate of reaction.

Oh good! I was doubting myself for a minute !!

Hey you know the equilibrium question? Did you put left and left or left and right or what.

I can't even remember . I think I counted the moles wrong for the pressure. Damn

I got left and left, but I think temperature was right, not to sure.

Increasing pressure favours reverse reaction because there is less pressure on the left (3.5 moles of gas on the left, 4 moles of gas on the right).

Also, would it matter if I spelled equilibrium incorrectly? My hands wanted to spell it "Equilibreum" I don't know

I got left and left, but I think temperature was right, not to sure.

A SORT OF UNNOFFICIAL MARK-SChEME (MAY BE OUT OF ORDER)

First Question
- C10H22
- (drawn) any branched isomer of c10h22 AND named [ i put 2-methylnonane ]
- (cracking question) C15H31 ----> C10H20 + C5H12 (any suitable equation-
- why does cracking hydrocarbons produce many products? C-C bond can break anywhere in the hydrocarbon chain
- (drawn) cyclo-octane i drew both skeletal and displayed formula of this just in case
- cyclo-alkanes are made because they burn more efficiently/ have a higher octane rating

Other question answers :
- homologous series: molecules that have same functional group but each successive member differs by a CH2
- burns with black smoke due to imcomplete combustion/ black smoke and yellow flame indicates there was a lack of oxygen therefore it did not combust completely.
- [question about why does something have 100% atom economy] because there was only 1 product produced in the reaction/ no waste products were produced in the reaction

Question about weird looking molecule thing showing E/z isomerism:
- functional groups present were an ester and an alkene (c-c double bond and a c-o double bond o)
- structure j is different from structure i because in I both the groups are on the same side of the double bond (Z isomerism) whereas in J each group is on the different sides of the c-c double bond (E isomerism)
Box Drawings for products of Alcohol when
1-oxidised
2-reacted with a carboxylic acid
3-dehydrated/hydrated


For the question about halogenoalkanes:
- most unreactive: i put the first one (N)
- Most reactive one had 2 halogens in it (I and Br)

- P had a lower b/p than Q because P contained Br and Q contained I. The C-I bond is longer than the C-Br bond, thus it is easier to overcome the C-I bond as it experiences less attraction to the nucleus of the C atom/ takes less energy to overcome C-I bond.

Had to choose one of the halogenoalkanes to demonstrate electrophilic addition (1) + diagram

For the Le chatelier question:
increasing temp: favours reverse reaction/position shifts to reduce temp, backward reaction endothermic
Increasing pressure: favors forward reaction, position of equilibrium moves right/less molecules on right hand side
removing catalyst: does not affect position of equilibrium
[not too sure about these^]

Define stereo isomers: have the same structural and molecular formula but different 3D arrangements of atoms in space


graph with percentages : 195.6 (approx) of something to 1 dp

i got 96.9% as the yield of something to do with propene (i cant remember)

got something like 4956 (approx) for the hess cycle question

4.96 X10-3 moles (of something cant remember again lol)

820 kjmol-1 as the enthalpy change when 230dm^3 is produces from N2 and O2

82 kJ as the next answer


For yeast question:
C6h12o6 ---> c2h50h + h20 (i forgot to balance do i lose a mark?)

conditions of fermentation reaction: 37 degrees Celsius (not sure if this counts), fermentation is anaerobic therefore NO OXYGEN, yeast as catalyst


CFCs - biodegradable alternatives:
i wrote HCFCs because i had NO idea, anybody know the answer?

Mass spec of Sulphur
M+ was the value of the furthest line to the right
S8
the m/z was the base (tallest) peak
S4+

free radical question:
Initiation: IBr ---> I* + Br* (in presence of UV)
Propagation 1 : Ch4 + Br* ---> Ch3* + HBr
Propagation 2: ch3* + IBr ----> CH3I + Br*


for propaation 2 i wrote Ch3* + I* -----> CH3I (but its wrong because its a termination step ! silly me!!!)


Termination step (any two radicals added)

The bond fission was homolytic (because 1 e- from the covalent bond goes to each atom)

Working out the X and Y substances from the IR spec:
empirical formula gave c4h8O
i got that it could be an aldehyde or a ketone (due to absorbtions stated)
i drew the aldehyde and ketone structure but didnt name them, will i lose a mark?

For the bolztman distribution:
temp: 2 curves, one lower than the other
increasing temp1 increases the mean energy of the particles therefore particles collide more and have more successful collisions

catalyst: 1 curve, 2 activation energy lines shown
adding a catalyst reduces the activation energy meaning more particles have the sufficient energy required to overcome the energy barrier to react. thus a greater rate of reaction.

anyone got link to the paper ?

A SORT OF UNNOFFICIAL MARK-SChEME (MAY BE OUT OF ORDER)

First Question
- C10H22
- (drawn) any branched isomer of c10h22 AND named [ i put 2-methylnonane ]
- (cracking question) C15H31 ----> C10H20 + C5H12 (any suitable equation-
- why does cracking hydrocarbons produce many products? C-C bond can break anywhere in the hydrocarbon chain
- (drawn) cyclo-octane i drew both skeletal and displayed formula of this just in case
- cyclo-alkanes are made because they burn more efficiently/ have a higher octane rating

Other question answers :
- homologous series: molecules that have same functional group but each successive member differs by a CH2
- burns with black smoke due to imcomplete combustion/ black smoke and yellow flame indicates there was a lack of oxygen therefore it did not combust completely.
- [question about why does something have 100% atom economy] because there was only 1 product produced in the reaction/ no waste products were produced in the reaction

Question about weird looking molecule thing showing E/z isomerism:
- functional groups present were an ester and an alkene (c-c double bond and a c-o double bond o)
- structure j is different from structure i because in I both the groups are on the same side of the double bond (Z isomerism) whereas in J each group is on the different sides of the c-c double bond (E isomerism)
Box Drawings for products of Alcohol when
1-oxidised
2-reacted with a carboxylic acid
3-dehydrated/hydrated


For the question about halogenoalkanes:
- most unreactive: i put the first one (N)
- Most reactive one had 2 halogens in it (I and Br)

- P had a lower b/p than Q because P contained Br and Q contained I. The C-I bond is longer than the C-Br bond, thus it is easier to overcome the C-I bond as it experiences less attraction to the nucleus of the C atom/ takes less energy to overcome C-I bond.

Had to choose one of the halogenoalkanes to demonstrate electrophilic addition (1) + diagram

For the Le chatelier question:
increasing temp: favours reverse reaction/position shifts to reduce temp, backward reaction endothermic
Increasing pressure: favors forward reaction, position of equilibrium moves right/less molecules on right hand side
removing catalyst: does not affect position of equilibrium
[not too sure about these^]

Define stereo isomers: have the same structural and molecular formula but different 3D arrangements of atoms in space


graph with percentages : 195.6 (approx) of something to 1 dp

i got 96.9% as the yield of something to do with propene (i cant remember)

got something like 4956 (approx) for the hess cycle question

4.96 X10-3 moles (of something cant remember again lol)

820 kjmol-1 as the enthalpy change when 230dm^3 is produces from N2 and O2

82 kJ as the next answer


For yeast question:
C6h12o6 ---> c2h50h + h20 (i forgot to balance do i lose a mark?)

conditions of fermentation reaction: 37 degrees Celsius (not sure if this counts), fermentation is anaerobic therefore NO OXYGEN, yeast as catalyst


CFCs - biodegradable alternatives:
i wrote HCFCs because i had NO idea, anybody know the answer?

Mass spec of Sulphur
M+ was the value of the furthest line to the right
S8
the m/z was the base (tallest) peak
S4+

free radical question:
Initiation: IBr ---> I* + Br* (in presence of UV)
Propagation 1 : Ch4 + Br* ---> Ch3* + HBr
Propagation 2: ch3* + IBr ----> CH3I + Br*


for propaation 2 i wrote Ch3* + I* -----> CH3I (but its wrong because its a termination step ! silly me!!!)


Termination step (any two radicals added)

The bond fission was homolytic (because 1 e- from the covalent bond goes to each atom)

Working out the X and Y substances from the IR spec:
empirical formula gave c4h8O
i got that it could be an aldehyde or a ketone (due to absorbtions stated)
i drew the aldehyde and ketone structure but didnt name them, will i lose a mark?

For the bolztman distribution:
temp: 2 curves, one lower than the other
increasing temp1 increases the mean energy of the particles therefore particles collide more and have more successful collisions

catalyst: 1 curve, 2 activation energy lines shown
adding a catalyst reduces the activation energy meaning more particles have the sufficient energy required to overcome the energy barrier to react. thus a greater rate of reaction.