[StellaRawr11]

(Original post by EffKayy)
Section A:

Spoiler:

Show

Maxwell boltsman
1) Kinetic energy
2) More collisions have energy greater than activation energy
3) Total area remains the same
Solubility of hydroxides increase, sulfates decrease
Magnesium carbonate and sodium (? Potassium) carbonate both decompose on STRONG heating – I got this wrong as I put only magnesium decomposes, however both do on strong heating. (Confirmed)
104.5 bond angle
Which halogenalkane one is incorrect? A
Iodine – hexane – purple
C was the dative covalent bond
D – one pi and one sigma bond
Nucleophiles are electron pair donors – low electron density
CFC – A (flammable)
Butan1ol Peak in C=O ketone
Butan2ol Immediately distlled – peak in C=O aldehyde
Trigonal planar
2methyl propane and butane = the one about surface area
Boiling point of HI > HBR = more electrons
Which one isn’t disproportionation? D. (Copper sulphate)
Flame colour – electrons drop back to lower energy level and EMIT energy/light
Oxidation number of Sulfur in the compound..? -2

Section B:

Spoiler:

Show

1) Darker blue because forward reaction is endothermic, so as the temperature increases more heat is added so moves to the endothermic side to absorb this heat. So moves to the right. (2)
2) Darker(/blue) (1) as moves to the right hand side of the equilibrium as there are fewer gaseous moles (1)
3)
-For the one about when they added a substance and it came up in reactants and products, dynamic equilibrium concentrations stayed constant but the rate of forward reaction and back were equal, the reactions were still continuing. (1) –
Titration
Moles of thiosulphate, (1), divide by 2. (2). Answer to above is same moles for ozone (1), volume is the moles of ozone times by the molar volume given – unit 1 stuff (1), concen was volume of that/100 * 10^6 = concentration.(1) 0.047.

Reliability – can be increased as you can repeat the experiment again. So mean titre etc, reliable
Decreased accuracy as smaller titration reading so greater percentage error..? (3)

Oxidation numbers
I got 0, 0 and -2 in that order.
Ozone is an oxidising agent (3)
Why ozone is better than chlorine?? (1) ?
ozone produces a harmless biproduct of O2..
Equations:

2KNO3  2KN02 + 02 (1)
2Ca(NO3)2  2CaO + O2 + 4NO2 (1)
Observation :Brown gas, white solid, red flame (2)
Why are the products different?
Ca2+ and K+ comparison. Ca2+ has a higher charge density, so is more polarising/distorting on the cation/ nitrate anion. So less stable  decomposes more (3)

Naming them
2 methyl, 2 chloro propane (1)
2 methyl propan-2-ol (1)
Correct skeletal formula of X (1)
Alcohol: Tertiary alcohol (1)
Type and mechanism: nucleophillic substitution (2)
Curly arrow shows the movement of a pair of electrons(lone pair) to the carbocation (1)
Structure – Trigonal planar, 120 degrees, as there electron pairs around central atom, max separation/ min repulsion (3)
Ethanolic ammonia:
Elimination
- 2methyl propene (2)
Isomers of Z –

That forms a ketone:

Butan-2-ol (1)  correct structural formula

Forms carboxylic acid :

Butan-1-ol – correct structural formula
2methyl propan-1-ol – correct structural formula (2)

Section C:

Spoiler:

Show

Green house gas -
Absorbs IR, remits IR towards all directions, including the earth, causing it warm up.
Causes climate change/global warming (2)
Water is a green house gas as it can change its dipole moment/polarity as the bonds stretch/bend/vibrate when it absorbs infrared radiation (2)
CH4 + 1 ½ O2  CO2 +2H20 (2) Balanced.
Or in multiples.
2NH3+ 1 1/2O2--> N2+ 3H2O (2)
Accept multiples.
[/B]
Cost of high pressure
Cost of strong pipes/reaction vessels needed to withstand high pressure (2)
Why is it better for reaction like this rather than combustion of methane directly ? (1)
Ammonia has a higher boiling point than methane: (4)
Ammonia has hydrogen bonding between molecules, Strongest intermolecular force,
More energy required to break hydrogen bonds, also has permanent dipole- dipole interactions.
Methane only has weak London forces
Ammonia also has more electrons, so more/stronger London forces
[B]
Two additional pieces of information required to compare fuels?
Atom economy..?
Availability..?
% Yield,
Products produced - if seperation is required, etc

‘pungent’ smell advantage (1)

Can be easily detected/identified if its there, also if there’s any leak you can identify it..? (1)
Why was petrol mixed with ammonia ? (1)
Makes combustion more smoother/easily ignitable

Hydrogen/Ammonia – not long term replacement as a fossil fuel (1)
Ammonia used as Hydrogen is made from the fossil fuels so would not be a good replacement. Biproduct of ammonia burning is not CO2

Grade boundary for an A ? 61/62

I think decrease in accuracy is because the mean that you obtained from the 5 results can be affected by outliers, therefore less closer to the true value
oh and ozone is better because doesnt contribute to ozone depletion into oxygen

[Future Medics]

(Original post by Arusa01)
HA I suck at French

MDR

[bobbyZ]

but last years test was pretty easy and the grade boundaries were at around 61 so this one should be higher if you think about it

[S1L3NTPR3Y]

Thought it was pretty good, that last bit confused me for ages but then I read the passage and basically got all the answers. It was in some parts hard, and loads of people at my school said they found the calculations hard. From looking at what others I am quite pleased, but hopefully low boundaries so I can get a good UMS score

[Tackla]

It was such a easy paper, but I messed it up.

[UserInvalid]

(Original post by EffKayy)
What 'additional' info did you guys say (2)
Why its mixed with petrol? (1)
Why the reaction is better than combustion of methane itself? (1)

for additional info I wrote :

1 - The cost
2 - How long it would last

Why the reaction is better than combustion of methane itself?

Less energy required, so less fuels used.

For the petrol I write that less non-renewable fuels will be used. I was not sure about this

wbu?

[EffKayy]

(Original post by UserInvalid)
for additional info I wrote :

1 - The cost
2 - How long it would last

Why the reaction is better than combustion of methane itself?

Less energy required, so less fuels used.

For the petrol I write that less non-renewable fuels will be used. I was not sure about this

wbu?

I wrote a lot for the additional info, but included those points too

Why the reaction is better
-Steam is renewable.
Also combustion produces co2 - green house gas.

Not sure about these questions =/
Yours seem pretty right though
loool

[UserInvalid]

(Original post by EffKayy)
I wrote a lot for the additional info, but included those points too

Why the reaction is better
-Steam is renewable.
Also combustion produces co2 - green house gas.

Not sure about these questions =/
Yours seem pretty right though
loool

Well lets hope the grade boundaries are low . Overall it was a good paper, I enjoyed it to be honest, and this was the big burden over me.

Now it got out of my way lol.

[Bord3r]

(Original post by EffKayy)
Section A:

Spoiler:

Show

Maxwell boltsman
1) Kinetic energy
2) More collisions have energy greater than activation energy
3) Total area remains the same
Solubility of hydroxides increase, sulfates decrease
Magnesium carbonate and sodium (? Potassium) carbonate both decompose on STRONG heating – I got this wrong as I put only magnesium decomposes, however both do on strong heating. (Confirmed)
104.5 bond angle
Which halogenalkane one is incorrect? A
Iodine – hexane – purple
C was the dative covalent bond
D – one pi and one sigma bond
Nucleophiles are electron pair donors – low electron density
CFC – A (flammable)
Butan1ol Peak in C=O ketone
Butan2ol Immediately distlled – peak in C=O aldehyde
Trigonal planar
2methyl propane and butane = the one about surface area
Boiling point of HI > HBR = more electrons
Which one isn’t disproportionation? D. (Copper sulphate)
Flame colour – electrons drop back to lower energy level and EMIT energy/light
Oxidation number of Sulfur in the compound..? -2

Section B:

Spoiler:

Show

1) Darker blue because forward reaction is endothermic, so as the temperature increases more heat is added so moves to the endothermic side to absorb this heat. So moves to the right. (2)
2) Darker(/blue) (1) as moves to the right hand side of the equilibrium as there are fewer gaseous moles (1)
3)
-For the one about when they added a substance and it came up in reactants and products, dynamic equilibrium concentrations stayed constant but the rate of forward reaction and back were equal, the reactions were still continuing. (1) –
Titration
Moles of thiosulphate, (1), divide by 2. (2). Answer to above is same moles for ozone (1), volume is the moles of ozone times by the molar volume given – unit 1 stuff (1), concen was volume of that/100 * 10^6 = concentration.(1) 0.047.

Reliability – can be increased as you can repeat the experiment again. So mean titre etc, reliable
Decreased accuracy as smaller titration reading so greater percentage error..? (3)

Oxidation numbers
I got 0, 0 and -2 in that order.
Ozone is an oxidising agent (3)
Why ozone is better than chlorine?? (1) ?
ozone produces a harmless biproduct of O2..
Equations:

2KNO3  2KN02 + 02 (1)
2Ca(NO3)2  2CaO + O2 + 4NO2 (1)
Observation :Brown gas, white solid, red flame (2)
Why are the products different?
Ca2+ and K+ comparison. Ca2+ has a higher charge density, so is more polarising/distorting on the cation/ nitrate anion. So less stable  decomposes more (3)

Naming them
2 methyl, 2 chloro propane (1)
2 methyl propan-2-ol (1)
Correct skeletal formula of X (1)
Alcohol: Tertiary alcohol (1)
Type and mechanism: nucleophillic substitution (2)
Curly arrow shows the movement of a pair of electrons(lone pair) to the carbocation (1)
Structure – Trigonal planar, 120 degrees, as there electron pairs around central atom, max separation/ min repulsion (3)
Ethanolic ammonia:
Elimination
- 2methyl propene (2)
Isomers of Z –

That forms a ketone:

Butan-2-ol (1)  correct structural formula

Forms carboxylic acid :

Butan-1-ol – correct structural formula
2methyl propan-1-ol – correct structural formula (2)

Section C:

Spoiler:

Show

Green house gas -
Absorbs IR, remits IR towards all directions, including the earth, causing it warm up.
Causes climate change/global warming (2)
Water is a green house gas as it can change its dipole moment/polarity as the bonds stretch/bend/vibrate when it absorbs infrared radiation (2)
CH4 + 1 ½ O2  CO2 +2H20 (2) Balanced.
Or in multiples.
2NH3+ 1 1/2O2--> N2+ 3H2O (2)
Accept multiples.
[/B]
Cost of high pressure
Cost of strong pipes/reaction vessels needed to withstand high pressure (2)
Why is it better for reaction like this rather than combustion of methane directly ? (1)
Ammonia has a higher boiling point than methane: (4)
Ammonia has hydrogen bonding between molecules, Strongest intermolecular force,
More energy required to break hydrogen bonds, also has permanent dipole- dipole interactions.
Methane only has weak London forces
Ammonia also has more electrons, so more/stronger London forces
[B]
Two additional pieces of information required to compare fuels?
Atom economy..?
Availability..?
% Yield,
Products produced - if seperation is required, etc

‘pungent’ smell advantage (1)

Can be easily detected/identified if its there, also if there’s any leak you can identify it..? (1)
Why was petrol mixed with ammonia ? (1)
Makes combustion more smoother/easily ignitable

Hydrogen/Ammonia – not long term replacement as a fossil fuel (1)
Ammonia used as Hydrogen is made from the fossil fuels so would not be a good replacement. Biproduct of ammonia burning is not CO2

Grade boundary for an A ? 61/62

Would Ozone not be acting as a reducing agent given how the oxidation number had decreased?

[bambi897064]

what exactly were the questions about methane reacting with water? was that to produce hydrogen to be used as a fuel?

[EffKayy]

(Original post by bambi897064)
what exactly were the questions about methane reacting with water? was that to produce hydrogen to be used as a fuel?

The equation of methane with water..?

[EffKayy]

(Original post by Bord3r)
Would Ozone not be acting as a reducing agent given how the oxidation number had decreased?

It's reduced itself, but it oxidises other substances =).

[UserInvalid]

(Original post by EffKayy)
It's reduced itself, but it oxidises other substances =).

Nice, got that right :P I wrote it is oxidizing agent

[EffKayy]

(Original post by UserInvalid)
Nice, got that right :P I wrote it is oxidizing agent

Was there a question for the equation between methane and steam; I cant remember my answer for that lol

[bambi897064]

(Original post by EffKayy)
The equation of methane with water..?

with steam i mean.

for the question after that one, after you'd written out the equation, did it ask why using methane and steam to produce hydrogen was better than burning methane directly?

[UserInvalid]

(Original post by EffKayy)
Was there a question for the equation between methane and steam; I cant remember my answer for that lol

Yeh there was, in section C. Just the question before asking Why the reaction is better than combustion of methane itself?

[EffKayy]

(Original post by bambi897064)
with steam i mean.

for the question after that one, after you'd written out the equation, did it ask why using methane and steam to produce hydrogen was better than burning methane directly?

Oh yeah, I said steam is renewable or something

[bambi897064]

(Original post by EffKayy)
Was there a question for the equation between methane and steam; I cant remember my answer for that lol

yes and i put that it produced c02 and h2 when apparently it was co and h2

[Bord3r]

(Original post by bambi897064)
with steam i mean.

for the question after that one, after you'd written out the equation, did it ask why using methane and steam to produce hydrogen was better than burning methane directly?

I put that it would produce a higher amount of energy as Hydrogen gives more energy compared to Methane, wasn't sure though.

[EffKayy]

(Original post by bambi897064)
yes and i put that it produced c02 and h2 when apparently it was co and h2

I'm sure it give you the answer in the passage!
I think it said co2 in the passage