AS Chemistry- helping each other out!

Fingerprint region is the region on the right hand side of the spectrum with so many complicated peaks and they are completely different for every compound so can be used to distinguish two compounds like butan-1-ol and butan-2-ol. They will have similar pattern on the left but completely different on the right.

So the two compounds in this question will have different fingerprint region.
The answer is A because the C=O peak is different in aldehyde and ketone I guess?

WAIT
don't they have same molecular ion peak in mass spectra? Are you sure it's not D
Posted from TSR Mobile

if they both have an Mr of 58, why is their molecular ion peak different? is it because it is talking about the FRAGMENTS that they produce? in that case, I understand, but the multiple choice option says 'different MOLECULAR ion peaks at different m/e ratios' so surely, if they're talking about FRAGMENTS they wouldnt incude the word MOLECULAR ION PEAK? as this implies its the total Mr of the molecules, the peak furthest to the right on the x-axis...

Reply 2621

C0balt

16

Original post by annie79

if they both have an Mr of 58, why is their molecular ion peak different? is it because it is talking about the FRAGMENTS that they produce? in that case, I understand, but the multiple choice option says 'different MOLECULAR ion peaks at different m/e ratios' so surely, if they're talking about FRAGMENTS they wouldnt incude the word MOLECULAR ION PEAK? as this implies its the total Mr of the molecules, the peak furthest to the right on the x-axis...

Molecular ion peak is the same!!

Reply 2622

Signorina

2

Original post by C0balt

If the molecule is polar.
That is when there's an electronegativity difference and when the centres of positive charge and negative charge do not coincide.

Thank you!
Also, how is boiling pt and melting pt different ???
on a past paper it says graphite has a high melting pt because of the covalent bonds. but iodine has a low boiling point because of vdw forces...
so does boiling pt depend on intermolecular forces and melting pt depend on chemical bonds?

Reply 2623

C0balt

16

Original post by Signorina

Thank you!
Also, how is boiling pt and melting pt different ???
on a past paper it says graphite has a high melting pt because of the covalent bonds. but iodine has a low boiling point because of vdw forces...
so does boiling pt depend on intermolecular forces and melting pt depend on chemical bonds?

They aren't any different. They depend on the forces of attraction between atoms/molecule /ions involved. Take silicon. The atoms are bonded covalently to neighbouring atoms so melting point is very high, and so is the boiling point

(edited 8 years ago)

Reply 2624

C0balt

16

Original post by annie79

is dipole dipole interactions the same as permanent dipole interactions? because I know that ketones have permanent dipole interactions and CH3Cl, but the overall ketone molecule is not polar

Yes it is
Ketone is polar

Reply 2625

annie79

9

Original post by C0balt

Molecular ion peak is the same!!

Oh yeah! It asks for the INCORRECT one, sorry, had a blonde moment x_x

Reply 2626

cheeky 12

2

Can anyone help me with the extraction of tungsten the equation I need to know and the conditions and the risk? Please

Posted from TSR Mobile

Reply 2627

Signorina

2

Original post by c0balt

they aren't any different. They depend on the forces of attraction between atoms/molecule /ions involved. Take silicon. The atoms are bonded covalently to neighbouring atoms so melting point is very high, and so is the boiling point

thank you!

Reply 2628

itsConnor_

11

Hello,

Could someone please show me how to do this question (F321)? Parts ii) and iii) http://gyazo.com/e19a53c6d9c7727fbbf4b1786e71f885
From January 2007 paper ( http://pastpapers.org/AS/chemistry/Foundation/2007_Jan_2811.pdf )

Thanks :smile:

Reply 2629

C0balt

16

Original post by itsConnor_

Hello,

Could someone please show me how to do this question (F321)? Parts ii) and iii) http://gyazo.com/e19a53c6d9c7727fbbf4b1786e71f885
From January 2007 paper ( http://pastpapers.org/AS/chemistry/Foundation/2007_Jan_2811.pdf )

Thanks :smile:

One Ca(OH)2 consists of three ions; Ca2+, OH- and another OH-. So in a mole of Ca(OH)2 there are three moles of ions.
How many electrons are there in one ion of OH-? 8+1 for oxygen and hydrogen, and another for the negative charge so 10. So in a mole of OH- ion there are ten moles of electrons

Reply 2630

samwillettsxxx

3

Original post by cheeky 12

Can anyone help me with the extraction of tungsten the equation I need to know and the conditions and the risk? Please

Posted from TSR Mobile

Hi tungsten is extracted using hydrogen. It can be extracted from its oxides with C however the product will be impure and brittle.
WO + 3H2 ----> W + 3H2O
hydrogen is expensive but you get pure tungsten
Hydrogen is explosive when mixed with air
Occurs at temperatures 700 celcius +

(edited 8 years ago)

Reply 2631

NutE

12

done a few AQA unit 2 past papers and I keep getting mid 80s, I need to get high 80s or above (need 121 ums) to get an overall A!!!!!! Grrrrrr

Reply 2632

samwillettsxxx

3

Original post by NutE

done a few AQA unit 2 past papers and I keep getting mid 80s, I need to get high 80s or above (need 121 ums) to get an overall A!!!!!! Grrrrrr

Me too lol keep getting 83.. Don't the grade boundaries change each year?

Reply 2633

NutE

12

Original post by samwillettsxxx

Me too lol keep getting 83.. Don't the grade boundaries change each year?

83 is an A in the past papers, i'm sure. Well done :smile:

yeah grade boundaries change every year, but if I get at least 88 then I know I've definitely got the 121 UMS i need. I'm actually aiming to get in the 90s but so far, no luck! I got 233 ums last year, so 7 away from an A!

Reply 2634

Frosty_A

When they say a chemical Is insouble, for Example BaSO4, does that mean it is insouble in any solution, say if it was Added to HCL or H2SO4.

If something is insoluble, when added to solution, what happens, does it just not react? Nothing happens visibly or is a precipitate formed?

Also what method could you used to determine a solubility of a Substance?

Reply 2635

FREYA2898

5

NEED HELP WITH THIS:
2.4) What is the maximum mass of iron (III) chloride that can be produced from 50.0 g of Fe and 100gof chlorine gas ?2 Fe + 3 Cl2 → 2 FeCl3

Reply 2636

frozo123

12

Original post by FREYA2898

NEED HELP WITH THIS:
2.4) What is the maximum mass of iron (III) chloride that can be produced from 50.0 g of Fe and 100gof chlorine gas ?2 Fe + 3 Cl2 → 2 FeCl3

Well if you look at the mole ratios
what similarity will you see between Fe and FeCl3

I'll ask you a similar question
So I've got 1/2 a bag of flour 1 carton of milk and 9eggs
To make a cake, I need 1/2 a bag of flour, 1 carton of milk, and 2 eggs
How many cakes can I make with my ingredients? hope that helps :smile:

Reply 2637