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OCR Chemistry A Exam Thread (Breadth - May 27 2016 and Depth - June 10 2016)

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Someone may have mentioned this before, but for the electrontic config was it an Mg atom or ion? I was like 99% sure it was atom but loads of people from my college said they changed it to ion at the last minute :s-smilie:

It was deffo atom! I checked :smile:

Reply 1121

asinghj

Guys, did you draw the activation energy?

Reply 1122

Cookiemonster057

Original post by asinghj

Guys, did you draw the activation energy?

No, I think it said you did not have to. Did you put in delta H and the axes labels (or were these given?)

(edited 7 years ago)

Reply 1123

Feisal_2374

****. I got 68.9% for the percentage yield... :angry:

Will I get full marks or lose a mark or two?

(edited 7 years ago)

Reply 1124

11...

for the enthalpy profile diagram. did u put N2 (g) and O2(g) as the reactants and N2O2 (g) as product.
and +82kjmol-1 was the enthalpy change right

Reply 1125

11...

for the difference between sigma and pi bond. I put sigma bond has a higher electron density than the pi bond. do u guys think i got a mark here

Reply 1126

APersonYo

Original post by 11...

it is methylpropanoic acid actually guys. it said that it was a secondary carbocation

The answer is 2-methylpropanoic acid. Reasons being if you google 2-methylpropanoic acid mass spectrum and butanoic acid mass spectrum, you will see that the 2-methylpropanoic acid spectrum matches the one found in the paper

Reply 1127

Feisal_2374

Original post by 11...

for the difference between sigma and pi bond. I put sigma bond has a higher electron density than the pi bond. do u guys think i got a mark here

Nah I think you have to talk about the sigma bond being spherical shaped and the pi bond being dumbbell shaped

Reply 1128

abitpissy

Original post by asinghj

Guys, did you draw the activation energy?

I'm certain it said you do not need to draw activation energy on it.

(edited 7 years ago)

Reply 1129

abitpissy

I said sigma bond is made from overlap of s orbital.
Pi bond is made from sideways overlap of P orbitals.

Reply 1130

11...

Original post by Feisal_2374

Nah I think you have to talk about the sigma bond being spherical shaped and the pi bond being dumbbell shaped

the s orbital is spherical and the p orbital is dumbbell shaped not the bonds

Reply 1131

Feisal_2374

Original post by 11...

the s orbital is spherical and the p orbital is dumbbell shaped not the bonds

Damn lol messed up

Reply 1132

11...

what mark do you guys think you got??? by the way where is the unofficial mark scheme. pls tell me the link for it if there is one :smile:

(edited 7 years ago)

Reply 1133

Feisal_2374

Hoping for 100/140 for a B

Reply 1134

11...

what do you think an A would be out of 140. hope it is 110/140

Reply 1135

Kienzan

For the last question I reached the correct answer and clearly drew out the structure of Compound C and everything. Got fragment ions and everything.
Only thing is, I didn't name it. Will I lose marks?

Reply 1136

11...

nobody did an unofficial mark scheme :frown:

Reply 1137

11...

I think I got 61/70 on that paper.

Reply 1138

11...

Original post by Kienzan

I don't think so. It just said identify compound C not name it. so I think you will get all the marks, unless ocr decides to be so specific

Reply 1139

asinghj

Original post by Questioness

I'm certain it said you do not need to draw activation energy on it.

It said something along the lines of you are not expected to know the activation energy, so I did the curve from reactants to products and labeled Ea but put no value