Year 12s: what will be the first way you research your future options? >>

A-level Chemistry Revision Squad!

Scroll to see replies

I'm guessing you'll have to find the moles of each one and see which is the highest
So from what I've worked out, you both get 1 mole for B and D
And from the molecular formula, I'll go with B because you get CaCl2 and not NaCl which is 2 moles of chlorine
Is that right?
I'm totally guessing lol

Posted from TSR Mobile

Ok. So you have calculated the number of moles. B is calcium chloride and this has 2 chloride ions. So the number of moles has to be divided by 2. So the true concentration of chloride will be half the amount you calculated. As D is sodium chloride there is only one chloride ion so that will be the true concentration.

From all of that the answer you need is d

Reply 601

Pink1998

For the AS AQA new spec, where can I find questions related to the practicals we did?

Reply 602

Enderbat1999

can some one quickly go over...

1) the bond enthalpy diagram with the arrows i don't get how to draw them

2) The new..
Electron Impact Ionisation
Electro spray Ionisation

3) explain why a 2+ ion has a different m/z and how to work it out

pls i dont understand any of this literally all i need to know then ill be ready

Reply 603

n2697

I got this picture from Doc Brown and i understand why there are 5 peaks but my question is:
how do you know how long to draw them (i.e. what their relative intensities are) especially the last three peaks
Thanks in advance :smile:

(edited 7 years ago)

Reply 604

username1898313

Original post by FemaleBo55

I was looking for a Chemistry Revision Thread but there were not any so I decided to make one :wink:

Feel free to ask questions regardless of your exam board (because chemistry is chesmitry), and we'll all be happy to help!

Can this SQUAD please visit this thread and help me..

http://www.thestudentroom.co.uk/showthread.php?t=4107175&p=65057641#post65057641

im in desperate need of help..

(edited 7 years ago)

Reply 605

username1898313

Can YOU PLEASE VISIT THIS THREAD:
http://www.thestudentroom.co.uk/showthread.php?t=4107175&p=65057641#post65057641
IM IN DESPERATE NEED OF HELP..

Reply 606

Enderbat1999

pls help me with this questionthe answer is 0.01/6.26 x100i know how to get 6.26 which is the mass of crucible and ore(g) - mass of crucible pls help me

Reply 607

Glavien

ImageUploadedByStudent Room1463997044.357145.jpg

How would you name this?

Posted from TSR Mobile

(edited 7 years ago)

Reply 608

Glavien

I thought it would be:
1,2-dimethylpropyl 2-methylpropanoate

Posted from TSR Mobile

Reply 609

ajohn123

Could someone help me describe the influence that non-standard conditions have on corrosion in terms of standard electrode potentials. Any help would be great, even a link would be appreciated.

Reply 610

Glavien

Lol, do you know if mines correct though?

Posted from TSR Mobile

Reply 611

ovo_zverit

Photochlorination is killing me

Reply 612

Farmerjj

Hi,
On mass spectrometry how do do you know which one the Molecular ion is? For example on this one the book says the Mr would be 86, but I would of said 85 because that's the large peak? Or is it always the peak that is the most to the right hand side?
Cheers

Reply 613

TeaAndTextbooks

Can someone explain how you do Question 2. Thanks

Posted from TSR Mobile

1464006603029.jpg29.6KB

Reply 614

LorryBalls

QUOTE=Farmerjj;65075469]Hi,On mass spectrometry how do do you know which one the Molecular ion is? For example on this one the book says the Mr would be 86, but I would of said 85 because that's the large peak? Or is it always the peak that is the most to the right hand side?
Cheers

The molecular ion peak would be 100. As it is normally the biggest mass peak and gives relative molecular mass

(edited 7 years ago)

Reply 615

Sandy_Vega30

Original post by TeaAndTextbooks

Can someone explain how you do Question 2. Thanks

Posted from TSR Mobile

The mole ratio between CxHy : CO2
50: 350
1 : 7

Hence there must be 7 carbons to balance both side. Therefore the answer is C7H16

Reply 616

TeaAndTextbooks

Original post by Sandy_Vega30

The mole ratio between CxHy : CO2
50: 350
1 : 7

Hence there must be 7 carbons to balance both side. Therefore the answer is C7H16

The answer is C though but I understand what your saying. Thank you

Posted from TSR Mobile

Reply 617

Marco1000

For ligand exchange, how do I know how many ligands get exchanged. For example, if I had Fe(H^2O)6 reacting with excess OH-, is there a way to find out if only 1 ligand is exchanged, maybe 2 or 3 etc?

Reply 618

Sandy_Vega30

Original post by TeaAndTextbooks

The answer is C though but I understand what your saying. Thank you

Posted from TSR Mobile

This is a June 2012 paper. The answer is B not C. :smile:

Reply 619

dpoojaraa

Original post by Glavien

Lol, do you know if mines correct though?

Posted from TSR Mobile

I would say it's 3-methyl butyl 2-methyl propanoate? Because when naming the alcohol, the longest chain is 4 carbons? So would the alcohol be 3-methyl butan-2-ol? But then I'm not sure how naming works with easters when using secondary/tertiary alcohols since the alcohol part becomes an alkyl group.