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

1. (Original post by Kathiye)
I'm not too sure of what you mean exactly by 'maths', but I'll try to give you a list:

Working out relative atomic mass from a mass spectrum
Half lives
Reacting masses (eg working out number of moles of a reactant and using it to find the mass of a product)
Concentrations
Empirical Formulas
Gas volumes
Avogadro's Constant (sometimes they ask how many particles/moles there are)
c=λv
E=hv
Enthalpy changes using bond enthalpies (sometimes linked to the above three)
Enthalpy changes using enthalpy changes of reactions
Hess, using the above
Bond angles, if that counts. xD
E=mc(change in)t

I think that's all! In other words, a lot.
I know its a lot, thank heavens I know most of it thankyou so much!
2. (Original post by Mtheodore)
1. Electron density
2. Bond enthalpies
3. Energy transferred (calorimeter)
4. Hess's Law
5. Percentage by mass
6. Empirical formulas
7. Half lifes
8. Relative abundance of isotopes
9. Calculations involving moles, volumes and mass
I think thats pretty much everything
Thank you so much for the help
3. (Original post by TheNote)
i don't think we need to know:
c=λv since that's a speed of light thing which we don't go near
Really? I'm sure I remember it coming up in a past paper... and it is in the book. Maybe I'm just imagining the question! It can't hurt to be aware of it, though.
4. (Original post by Kathiye)
Really? I'm sure I remember it coming up in a past paper... and it is in the book. Maybe I'm just imagining the question! It can't hurt to be aware of it, though.
i've never come accross it, and I don't see it in the revision guide or the spec.
"differences: bright/coloured lines on a black background

or black lines on coloured/bright
background;

understand the relationship between the energy emitted or absorbed

and the frequency of the line produced in the spectra;

∆E=hν"
5. (Original post by TheNote)
i've never come accross it, and I don't see it in the revision guide or the spec
It was probably just that xD But like I said, it's mentioned in the textbook. They could just decide to be weird this year.

... Not trying to worry anyone or anything.
6. (Original post by Kathiye)
It was probably just that xD But like I said, it's mentioned in the textbook. They could just decide to be weird this year.

... Not trying to worry anyone or anything.
hahaha no problem what page is it on?
7. (Original post by TheNote)
hahaha no problem what page is it on?
I can't remember exactly, but it's the one about the wave theory of light, I think?
8. (Original post by Kathiye)
I can't remember exactly, but it's the one about the wave theory of light, I think?
oh i found it page 119 or something, it's giving you a general explanation and background on electromagnetic radiation so you understand what's going on rather than they just throwing E = hv at you and hoping for the best, however it's not in the entire spec so don't expect it to be the exam.
9. hope it all goes well, and they don't put in anything we don't know

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10. Does anyone know what calculations we have to do for mass spec?
11. (Original post by autodidactmedic)
Does anyone know what calculations we have to do for mass spec?
The relative abundance one

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12. (Original post by SyedaK)
The relative abundance one

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(Original post by autodidactmedic)
Does anyone know what calculations we have to do for mass spec?
Say if you got isotopic masses with abundance
16-65%
17-35%

Ar of element=
(16 X 65)+(17 X35)

= 16.35
----------------------
100
13. So apparently trying to help people gets me a neg... oh well. I had to get one somewhere.

Good luck everyone! Hopefully it won't be as weird as my biology exam xD
14. Last minute revision notes! http://getrevising.co.uk/revision-cards/348137#11
15. I hate it when they say why the practical procedure led to a less negative value for enthalpy change of combustion of....
Wat do you say?
Once they didn't allow nonstandard conditions used in the MS and didn't allow even evaporation of fuel from wick

Help
16. What do they mainly accept for above ^?
17. (Original post by Kathiye)
So apparently trying to help people gets me a neg... oh well. I had to get one somewhere.

Good luck everyone! Hopefully it won't be as weird as my biology exam xD
Did you do Edexcel biology
18. Good luck everyone, remember stay calm and read the question carefully, and underline sig figures and key words
19. (Original post by krisshP)
I hate it when they say why the practical procedure led to a less negative value for enthalpy change of combustion of....
Wat do you say?
Once they didn't allow nonstandard conditions used in the MS and didn't allow even evaporation of fuel from wick

Help
You write that endothermic takes in energy from the surrounding and is deltaH+ and is bond breaking
exothermic gives out energy to the surroundings and is deltaH- and is bond forming, therefore more energy is being released than taken in. There is a higher value for exothermic than endothermic

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