M4S5 – Instrumental Analysis IR & MS

Which is the correct sequence of events that takes place in a modern mass spectrometer in the production of a mass spectrum from a sample of an element or compound?

The number of peaks in the mass spectrum of an element indicates the number of:

Species such as CH₃⁺ and Br⁺ can be detected in a mass spectrum but do not occur in chemical reactions under typical laboratory conditions.

This is because in a mass spectrometer:

The mass spectrum of chlorine includes three peaks at mass-to-charge ratios of 70, 72 and 74.

The order of the heights of these peaks is:

The mass spectrum of copper has two significant peaks. The peak at 63 has a relative abundance of 69 and the peak at 65 has a relative abundance of 31.

This shows that the relative atomic mass of copper is:

The peak with the largest mass to charge ratio in the mass spectrum of an alkane is detected at mass-to-charge ratio = 58.

This shows that the hydrocarbon:

There are two main peaks in the infra-red spectrum of carbon dioxide.

This shows that carbon dioxide molecules:

Which of these organic compounds show a broad absorption peak caused by hydrogen bonding affecting a functional group.

(i) propanol

(ii) propanal

(iii) propanoic acid

(iv) propanone

Infra-red absorption ranges for some bonds are as follows:

C-H, 2850 - 3300 cm^-1

C=C, 1620 - 1680 cm^-1

C=O, 1680 - 1750 cm^-1

C-O, 1000 - 1300 cm^-1

O-H (alcohols), 3230 - 3550 cm^-1

O-H (acids), 2500 - 3000 cm^-1

The IR spectrum of propanal has one particularly strong absorption peak

This can be expected to be at:

A compound X with the molecular formula C₄H₁₀O has a broad peak in its IR spectrum at 3500cm^-1.

Oxidation of X with excess potassium dichromate(VI) gives a product Y which is not an acid and does not reduce Fehling's solution.

Y has a strong peak in its IR spectrum at 1700cm^-1.

Identify X and Y. (See also the data in question 9.)