A2 Chem4 question? how do u do this? Watch

rakib567
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uhhmm i don't get it

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TajwarC
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(Original post by rakib567)
uhhmm i don't get it

Which part?
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rakib567
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(Original post by TajwarC)
Which part?
b and c :confused:

i cut out the other easy bits of the question
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TajwarC
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(Original post by rakib567)
b and c :confused:

i cut out the other easy bits of the question
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
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rakib567
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(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?
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rakib567
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GOT IT! thanks for the help you need a rep
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TajwarC
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(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)
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TajwarC
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(Original post by rakib567)
GOT IT! thanks for the help you need a rep
Thanks
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rakib567
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(Original post by TajwarC)
Thanks
i expected an answer next morning but u are here at midnight helping the chemistry community
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