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Ocr f321 23 may 2013~official discussion thread

Reply 820

MathsNerd1

17

Original post by Geronimo!

what about that ionic lattice question, i put K+ and Cl- in those circles :confused:

Yeah that's correct

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Reply 821

theworld

When dissolved in water it will slowly decompose, releasing chlorine, oxygen and sodium and hydroxide ions.

4 NaClO + 2 H2O → 4 Na+ + 4 OH- + 2 Cl2 + O2

it said sodium hydroxide didn't it?

Reply 822

klapsar

First off, for the question about what reagent to add to the mixture of calcium bromide and iodide, you add concentrated ammonia right?

My friend was wondering if just "ammonia" would be an acceptable answer, i.e. without specifying that it's concentrated.

Reply 823

Happy03

Original post by theworld

me too

, how many marks do we get?

I'm not sure :frown:

was so confident it was right :frown:

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Reply 824

Adalbosco

1

Does anyone remember what they got for the volume question?

Reply 825

anonymousecheese

2

Original post by Geronimo!

what about that ionic lattice question, i put K+ and Cl- in those circles :confused:

Yeah thats right
but you had to make sure that none of thr k+ were connected to the other k+
k+ cl- k+
cl- k+ cl-
k+ cl- k+
but it was 3D.

Reply 826

abudabu

2

Original post by Adalbosco

Does anyone remember what they got for the volume question?

First for me was 360, then 22.5

Reply 827

MathsNerd1

17

Original post by Dr. Django

Hopefully same. I'm just waiting for some sort of mark scheme

Me too, although the stupid errors I made were unreal!!! I forgot the charges for the lattice, put the wrong protons and therefore wrong isotope, wrong equation between water and Cl2 and the wrong ion responsible for bleaching :-/

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Reply 828

theworld

Original post by klapsar

First off, for the question about what reagent to add to the mixture of calcium bromide and iodide, you add concentrated ammonia right?

My friend was wondering if just "ammonia" would be an acceptable answer, i.e. without specifying that it's concentrated.

reagent was aqueous silver nitrate.

the last part of the question was Conc ammonia

Reply 829

Dr. Django

12

Original post by Adalbosco

Does anyone remember what they got for the volume question?

360 and 22.5 (I think there were 2)

Reply 830

Harryshah

Original post by Geronimo!

what about that ionic lattice question, i put K+ and Cl- in those circles :confused:

I didn't put the plus and the minus! damnnnnnnn

Reply 831

MathsNerd1

17

Original post by klapsar

First off, for the question about what reagent to add to the mixture of calcium bromide and iodide, you add concentrated ammonia right?

My friend was wondering if just "ammonia" would be an acceptable answer, i.e. without specifying that it's concentrated.

No it had to be conc.

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Reply 832

MathsNerd1

17

Original post by Adalbosco

Does anyone remember what they got for the volume question?

160?

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Reply 833

jackitsme

JUST TO CLEAR THINGS UP:
NH3 has hydrogen bonds BETWEEN MOLECULES
PH3 Has vaan der waals forces BETWEEN MOLECULES but dipole-dipole interactions

THIS QUESTION IS ABOUT MELTING POINT>that means forces between molecules as they break to form the melted form,so PH3 is van der waals! it has to be cause it has vaan der waals between molecules !

im just saying but i cant be wrong? just saying,so feel free to correct :smile: