Analytical Techniques

Compound L contains carbon atoms. It is analysed in a mass spectrometer.

The table shows the relative abundance of the only two peaks recorded with $m/e$ greater than 127.

How many carbon atoms are present in one molecule of compound L?

Options

A   5
B   7
C   8
D   10

Hydrocarbon X is saturated. Each molecule contains one ring of carbon atoms.

The mass spectrum of hydrocarbon X is measured.

The peak representing the $\text{M}^+$ ion is $14\text{ mm}$ high.

The peak representing the $[\text{M}+1]^+$ ion is $0.77\text{ mm}$ high.

What is the $m/e$ value for the $\text{M}^+$ ion of X?

Options

A   56
B   58
C   70
D   72

The mass spectrum of $\text{CH}_3\text{Cl}$ shows a molecular ion peak, $\text{M}^+$, at the $m/e$ value of 50 with a relative abundance of $18.0\%$.

Other peaks are present in the mass spectrum.

What is seen in the mass spectrum at the $m/e$ value of 52?

Options

A   a peak with relative abundance of $4.5\%$
B   a peak with relative abundance of $6.0\%$
C   a peak with relative abundance of $18.0\%$
D   a peak with relative abundance of $54.0\%$

The mass spectrum of an organic compound has the following features.

• The molecular ion peak is at $m/e = 60$. This peak has a relative intensity = 100.
• There is a peak at $m/e = 61$, which has a relative intensity = 2.2.
• There is no fragment peak at $m/e = 17$.
• There is a fragment peak at $m/e = 31$.

What could be the identity of the organic compound?

Options

A   methyl methanoate, $\text{HCOOCH}_3$
B   methoxyethane, $\text{CH}_3\text{OC}_2\text{H}_5$
C   ethanoic acid, $\text{CH}_3\text{COOH}$
D   propan-2-ol, $\text{CH}_3\text{CH(OH)CH}_3$

The mass spectrum of element Z is shown.

What is element Z?

Options

A   arsenic
B   chlorine
C   gallium
D   tungsten

The purity of a compound can be determined using infrared spectroscopy.

The table gives the characteristic infrared absorption frequencies for some selected bonds.

Propan-2-ol is made by hydration of propene. A sample of the product is obtained.

Which feature of the infrared spectrum of the product would show that no propene remains in the product?

Options

A   absorption in the $2900\text{ cm}^{-1}$ region
B   strong absorption below $1000\text{ cm}^{-1}$
C   the lack of absorption at or near $1250\text{ cm}^{-1}$
D   the lack of absorption at or near $1550\text{ cm}^{-1}$

The infrared spectrum of a compound is shown.

Which functional group could the compound contain?

Options

A   alcohol
B   carboxylic acid
C   ester
D   nitrile

Compound X reacts with acidified $\text{K}_2\text{Cr}_2\text{O}_7$ to form compound Y.

The infrared spectrum of compound Y is shown.

What is the identity of compound X?

Options

A   propan-1-ol
B   propan-2-ol
C   propanone
D   propanoic acid

A sample of but-2-enoic acid, $\text{CH}_3\text{CH=CHCOOH}$, is analysed using infrared spectroscopy.

The infrared spectrum shows a broad peak in the range $2500\text{--}3000\text{ cm}^{-1}$.

Which bond is responsible for this peak?

Options

A   C=C
B   C=O
C   C–O
D   O–H

The diagram shows the mass spectrum of a sample of chlorine. Peaks V, W, X, Y and Z are labelled.

Which statements about this spectrum are correct?

1   The relative atomic mass of chlorine can be calculated from the abundances and $m/e$ values of 2 of the 5 peaks.
2   $37.0\text{ g}$ of the species responsible for peak Z contains $3.011 \times 10^{23}$ molecules.
3   The relative molecular mass of chlorine can be calculated from the abundances and $m/e$ values of peaks X, Y and Z.

Options

A   1, 2 and 3
B   1 and 2 only
C   1 and 3 only
D   2 and 3 only