Edexcel Chemistry IGCSE 1C Unofficial Mark Scheme 19th May 2016

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sorry to ask another, but how many marks overall do you think we can afford to lose in order to still get a comfortable a*?

Reply 261

conradliebers

Original post by exams2

sorry to ask another, but how many marks overall do you think we can afford to lose in order to still get a comfortable a*?

*tired sighs* around 130-135 out of 180 is roughly the boundary, so comfortable would be 145.

Reply 262

username2613945

Original post by conradliebers

*tired sighs* around 130-135 out of 180 is roughly the boundary, so comfortable would be 145.

thank you and sorry ahah in a bit of a panic

Reply 263

amyseymour

Was there a substitution question or did I make that up?

Reply 264

kcajgreening

Original post by exams2

sorry to ask another, but how many marks overall do you think we can afford to lose in order to still get a comfortable a*?

Depending on the grade boundaries, A* is around 76% so perhaps around 41 marks?

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(edited 7 years ago)

Reply 265

Carlos Santana

Original post by MMay2000

I thought if at 25cm3 was in excess, all the magnesium has reacted, adding more acid doesn't change that, all the magnesium will react at the same rate the same way. increasing heat given out can only be affected by the mass of magnesium used.

someone explain i am probs wrong

No you're right, it has no effect on rate. This unofficial mark scheme is very flawed

Reply 266

bbk717

I know that i am incorrect, but for the working out the mass of max water produced question I got 1.4g. Would anyone who got 0.9g let me know if they came across that number in their working. Thanks

Reply 267

Shahzeb_m

Original post by exams2

sorry to ask another, but how many marks overall do you think we can afford to lose in order to still get a comfortable a*?

for triple science students, I would say 150/180 is a comfortable A* so you could afford to lose 30 marks across both papers. If just double then I would say 100/120 so you could afford to lose 20 marks in the double award paper. Both these scores give 83% which is almost always an A*

Reply 268

Carlos Santana

Original post by conradliebers

*tired sighs* around 130-135 out of 180 is roughly the boundary, so comfortable would be 145.

It hasn't dipped below 140 in a few years

Reply 269

conradliebers

Original post by Carlos Santana

It hasn't dipped below 140 in a few years

If so, I'd actually expect it to rise if paper 2 is like paper 1.

Reply 270

Castro300

Original post by conradliebers

Yes

Wait, i only showed formula for the bromopropane not hbr cuzz it said one of the products?????

Reply 271

Carlos Santana

Original post by conradliebers

If so, I'd actually expect it to rise if paper 2 is like paper 1.

Yeah probably will be about 144 doubt it will be much higher

Reply 272

conradliebers

Original post by Castro300

Wait, i only showed formula for the bromopropane not hbr cuzz it said one of the products?????

Yes thats what you are supposed to do, but someone else put both in and I said that would be okay because the additional H-Br they put in would be ignored.

Reply 273

Castro300

Original post by conradliebers

Yes thats what you are supposed to do, but someone else put both in and I said that would be okay because the additional H-Br they put in would be ignored.

With the calcium and water, could i say bubbles and that calcium moves around

Reply 274

Screme

Original post by MattB_

It depends on the difficulty of paper 2. If paper 2 is of a similar difficulty I would imagine the grade boundary to between 137-140 (out of 180)?

I think the calcium carbonate one was:
Calcium oxide
Calcium chloride
Calcium hydrogen carbonate (a question later in the paper basically gave this answer away)