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Need help fast with chem questions! please

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1) Which of the following statements is false?

a) A gas chromatograph can be coupled to a mass spectrometer

b) Gas chromatography cannot produce a specific identification of a chemical substance

c) In mass spectrometry, a chemical substance enters a chamber where it is fragmented by high-energy electrons

d) Many chemical susbstances have similar mass spectra fragmentation patterns

e) A fragmentation pattern provides a fingerprint of the chemical substance being analysed

I thought this was c but i got it wrong; would like to know the correct answer thanks

 

 

2) A compound can be tentatively identified by gas chromatography from its:

a) Peak shape

b) Rf value

c) Partition coefficient

d) Retention time

e) Peak height

 

Thought this was a but got that wrong too, i think it could be d?

 

asked Mar 4, 2015 in CHEMISTRY by zoe Apprentice

2 Answers

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Best answer

Step 1 :

1).

The fragmentation of molecular ions into an assortment of fragment ions is a mixed blessing.

The nature of the fragments often provides a clue to the molecular structure, but if the molecular ion has a lifetime of less than a few microseconds it will not survive long enough to be observed.

Without a molecular ion peak as a reference, the difficulty of interpreting a mass spectrum increases markedly.

Step 2 :

" Many chemical substances have similar mass spectra fragmentation patterns " is the false statement.

Option (d) is the correct choice.

Solution :

Option (d) is the correct choice.

answered Mar 4, 2015 by lilly Expert
selected Mar 4, 2015 by zoe
THANK YOU!! :D
0 votes

Step 1 :

2).

Definition :

The interval between the instant of injection and the detection of the component is known as the retention time.

Step 2 :

A compound can be tentatively identified by gas chromatography from its retention time.

Option (d) is the correct choice.

Solution :

Option (d) is the correct choice.

answered Mar 4, 2015 by lilly Expert

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