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A2 Chem4 question? how do u do this?

uhhmm i don't get it

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Reply 1
Original post by rakib567
uhhmm i don't get it


Which part?
Reply 2
Original post by TajwarC
Which part?


b and c :confused:

i cut out the other easy bits of the question :tongue:
Reply 3
Original post by rakib567
b and c :confused:

i cut out the other easy bits of the question :tongue:

B) basically, the number of different atoms that form the compound. Each one will produce a peak. Be careful with the chlorine though, account for the fact there's two isotopes.

The m/z value is the sum of the molecular masses of the constituent elements in the compound. Again be careful as to what value you use for chlorine

C) apparently this is a so called "A* question". Essentially you need high temperatures to maximise waste destruction in incinerators, which thus prevents the dioxins from forming
(edited 9 years ago)
Reply 4
Original post by TajwarC
B) basically, the number of different atoms that form the compound. Each one will produce a peak. Be careful with the chlorine though, account for the fact there's two isotopes.

The m/z value is the sum of the molecular masses of the constituent elements in the compound. Again be careful as to what value you use for chlorine

C) apparently this is a so called "A* question". Essentially you need high temperatures to maximise waste destruction in incinerators, which thus prevents the dioxins from forming


ok seems like C is just knowledge but i still don't understand b. in terms of the molecular ion peaks (M+) how many would u expect and why?
Reply 5
GOT IT! thanks for the help you need a rep :biggrin:
Reply 6
Original post by rakib567
ok seems like C is just knowledge but i still don't understand b. in terms of the molecular ion peaks (M+) how many would u expect and why?

So the molecular formula is C12H4O2Cl4

We have carbon, hydrogen, oxygen and chlorine. We could expect a peak from each of those, but as there are two isotopes of chlorine we can expect 1 more, so 5 all together

For the m/z part, this equals the molecular mass of the compound. We use a value of 35 for chlorine as this is the most abundant isotope so essentially it's (12x12)+(4x1)... and so on

The m/z of the ion peak is the same as the mr of the compound because it has the highest m/z ratio, it's a molecule that hasn't fragmented and has a charge of +1 (m/z is a ratio, mass over 1 is the same as the original mass)
Reply 7
Original post by rakib567
GOT IT! thanks for the help you need a rep :biggrin:

Thanks :biggrin:
Reply 8
Original post by TajwarC
Thanks :biggrin:


i expected an answer next morning but u are here at midnight helping the chemistry community :biggrin:

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