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OCR B (Salters) Chemistry F331 (Chemistry for Life) Thursday 23rd May Exam Discussion

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What did everyone say for the question where we were asked to say 2 things we'd observe when calcium mixes with water or whatever the question was?

Precipitate and bubbles formed.

Reply 241

krisshP

Original post by Zuzuzu

Precipitate and bubbles formed.

I just said anything that came to my mind. I threw in effervescence, bubbling, but I don't think I threw in precipitate :frown:

(edited 10 years ago)

Reply 242

SyedaK

Original post by Zuzuzu

Precipitate and bubbles formed.

Well I stupidly said fizzing and dissolving. Would I get any mark at all :frown:

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Reply 243

Kathiye

Original post by Zuzuzu

Precipitate and bubbles formed.

Do you think I'd get a mark for saying it went alkaline? I mentioned universal indicator... does it even go alkaline? Oh no... I thought that this had gone so well. That's another mark gone.

Reply 244

CoolRunner

Original post by Kathiye

Do you think I'd get a mark for saying it went alkaline? I mentioned universal indicator... does it even go alkaline? Oh no... I thought that this had gone so well. That's another mark gone.

I said:

1) Fizzing, hydrogen gas formed
2) Ca reacts vigorously, starts to melt & calcium hydroxide is formed.

Reply 245

username638250

Original post by DomGunstone

Yeah. How did you find the calculations?

I usually find them more difficult, but I got them both correct this time; I don't know what's wrong with me... :smile:

I found them fine, lol.
I put calcium dissolves in water which is incorrect, for one of the observations. Oh well.

Reply 246

TheNote

Original post by krisshP

1 HF-->50%-->6000 years
2HF-->25%-->12,000 years
3HF-->12.5%-->18,000 years

They told you the HF was 6000 years

I know but they said count rate or something for the percentage which is something i've never heard of before xD

Reply 247

TheNote

Original post by CoolRunner

I said:

1) Fizzing, hydrogen gas formed
2) Ca reacts vigorously, starts to melt & calcium hydroxide is formed.

it asks you what you would observe so saying that you "saw hydrogen gas" is actually wrong, you would see a gas and bubbling/fizzing also you observe a precipitate formed
you will probs gets the marks unless they're pedantic about it.

Reply 248

TheNote

Original post by Kathiye

I thought that the question there was about oxygen... did I read it wrong? x.x Oh no! I get it now. Looks like that's another mark that I lost... I assume that it was an ion where the oxygen had an atomic mass of 18.

no it was, the oxygen atom had an isotope of MR 18 plus 2 hydrogens making it an MR of 20

so you could of written:
H₂¹⁸O

Reply 249

krisshP

Original post by TheNote

What about effervescence, I think it means bubbling, no too sure what it means myself,

Reply 250

ashxx

any unofficial mark schemes up yet??

Reply 251

HolliePA

Original post by SyedaK

So you didn't do them?

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The last page was only 3 marks, don't worry too much! :smile:

Reply 252

The_Blade

Can someone so a mark scheme already? The fact that you can only lose 10 marks to get an A sucks. ****

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Reply 253

tasniaa

Original post by The_Blade

Can someone so a mark scheme already? The fact that you can only lose 10 marks to get an A sucks. ****

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agreed

Reply 254

amber109

I felt I did well in that test, until I started reading this thread :frown:

Reply 255

ashxx

Original post by The_Blade

Can someone so a mark scheme already? The fact that you can only lose 10 marks to get an A sucks. ****

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what really?? 50 to get an A? surely not....? sorry if im mistaken :frown:

Reply 256

CoolRunner

Original post by ashxx

what really?? 50 to get an A? surely not....? sorry if im mistaken :frown:

In january it was 48 for an A...

Reply 257

ashxx

Original post by CoolRunner

In january it was 48 for an A...

would be around the same then :/ i guess it wasn't a hard exam really.....just hope it goes well really

Reply 258

_Lydia_

what did people get for the two assumptions questions?
one was for the half life Q and the other for the heating fuel/ enthalpy question

Reply 259

The_Blade

for the carbon neutrual and sustainable one i said its sustainable cos it doesnt cause problems in the future and its carbon neutral cos roughly the same amount of c02 is given out and given in.

i didnt mention the words rewnewable,crops,plants... :frown:

how many marks you think i got

(edited 10 years ago)