Jan 2005 Question Chem AQA Mod 1

sample of cooper contains 63CU & 65Cu. relative atomic mass less than 64. mass spectrum shows major peaks with m/z values of 63 and 65.

(i) explain why Ar of this sample less than 64

(ii) explain how cu atoms converted into Cu+ ions in mass spec?

in addition to major peaks at m/z 63 and 65, much smaller peaks at m/z 31.5 and 32.5 are present on spectrum. identify the ion responsible for the peak at m/z 31.5, explain why your chosen ion has this m/z value and one reason why peak is small.

(iii) Identify The ion.........?
Explanation of m/z value....?
Reason why peak is small?
(6 marks)

im stuck on this question from jan 2005 paper
can neone help me :biggrin:

thankz

Reply 1

oxymoron

7

Dipz

sample of cooper contains 63CU & 65Cu. relative atomic mass less than 64. mass spectrum shows major peaks with m/z values of 63 and 65.

(i) explain why Ar of this sample less than 64

(ii) explain how cu atoms converted into Cu+ ions in mass spec?

in addition to major peaks at m/z 63 and 65, much smaller peaks at m/z 31.5 and 32.5 are present on spectrum. identify the ion responsible for the peak at m/z 31.5, explain why your chosen ion has this m/z value and one reason why peak is small.

(iii) Identify The ion.........?
Explanation of m/z value....?
Reason why peak is small?
(6 marks)

im stuck on this question from jan 2005 paper
can neone help me :biggrin:

thankz

Ar is less than 64 because there is more of the 63 isotope than the 65 in naturally occurring copper, so the average (relative atomic mass) is closer to 63.

In the mass spec, Cu atoms have an electron knocked off them by a beam of high energy electrons. This leaves one less electron on the Cu so a Cu+ ion is formed.

The ion with a lower peak is the 2+ ion. Since the charge is doubled, the m/z ratio is halved (ie z is doubled). This happens when the electron beam hits the Cu+ ion and knocks another electron off it.
The peak is much smaller as it is rare for the beam to hit the same atom twice, since there are many more Cu atoms than Cu+ ions in the chamber so the probability of hitting a Cu+ ion is reduced.

Reply 2

Dipz

OP

lol thanks oxymoron looks easy wen u get the answers... :biggrin:

btw ne1 got the markscheme for this paper?

Jan 2005 Question Chem AQA Mod 1

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