Structure 1. Models of the particulate nature of matter

1.1 Introduction to the particulate nature of matter

1.2 The nuclear atom

1.3 Electron configurations

1.4 The mole

1.5 Ideal gases

Structure 2. Models of bonding and structure

2.1 The ionic model

2.2 The covalent model

2.3 The metallic model

2.4 From models to materials

Structure 3. Classification of matter

3.1 The periodic table

3.2 Functional groups: Organic compounds

Reactivity 1. What drives chemical reactions?

1.1 Measuring enthalpy changes

1.2 Energy cycles

1.3 Energy from fuels

Reactivity 2. How much, how fast and how far?

2.1 Amount of chemical change

2.2 Rate of chemical change

2.3 Extent of chemical change

Reactivity 3. What are the mechanisms of chemical change?

3.1 Proton transfer reactions

3.2 Electron transfer reactions

3.3 Electron sharing reactions (Radicals)

3.4 Electron-pair sharing reactions

IB Chemistry HL 3.2 Functional groups: Organic compounds Question Bank

[Maximum number: 6]

Urea, $\left(\mathrm{H}_{2} \mathrm{~N}\right)_{2} \mathrm{CO}$ , is excreted by mammals and can be used as a fertilizer.

(a)

The mass spectrum of urea is shown below.

Reference Database Number 69, Eds. P.J. Linstrom and W.G. Mallard, National Institute of Standards and Technology, Gaithersburg MD, 20899, doi:10.18434/T4D303, (retrieved May 31, 2018).]

Identify the species responsible for the peaks at m / z=60 and 44 .

60:

44:

[ 2 ]

(b)

The IR spectrum of urea is shown below.

Identify the bonds causing the absorptions at $3450 \mathrm{~cm}^{-1}$ and $1700 \mathrm{~cm}^{-1}$ using section 26 of the data booklet.

$3450 \mathrm{~cm}^{-1}$ :

$1700 \mathrm{~cm}^{-1}$ :

[ 2 ]

(c)

(i)

Predict the number of signals in the ${ }^{1} \mathrm{H} \mathrm{NMR}$ spectrum of urea.

[ 1 ]

(ii)

Predict the splitting pattern of the ${ }^{1} \mathrm{H}$ NMR spectrum of urea.

[ 1 ]

[Maximum number: 4]

Chlorine undergoes many reactions.

(a)

(i)

Ethoxyethane (diethyl ether) can be used as a solvent for this conversion.

Draw the structural formula of ethoxyethane.

[ 1 ]

(ii)

Deduce the number of signals and chemical shifts with splitting patterns in the ${ }^{1} \mathrm{H}$ NMR spectrum of ethoxyethane. Use section 27 of the data booklet.

[ 3 ]

[Maximum number: 2]

Ethane-1,2-diol, $\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ , has a wide variety of uses including the removal of ice from aircraft and heat transfer in a solar cell.

(a)

Predict the ${ }^{1} \mathrm{HNMR}$ data for ethanedioic acid and ethane-1,2-diol by completing the table.

[ 2 ]

[Maximum number: 6]

A4.406 g sample of a compound containing only C, H and O was burnt in excess oxygen. 8.802 g of $\mathrm{CO}_{2}$ and 3.604 g of $\mathrm{H}_{2} \mathrm{O}$ were produced.

(a)

The following spectrums show the Infrared spectra of propan-1-ol, propanal and propanoic acid.

Identify each compound from the spectra given, use absorptions from the range of $1700 \mathrm{~cm}^{-1}$ to $3500 \mathrm{~cm}^{-1}$ . Explain the reason for your choice, referring to section 26 of the data booklet.

[ 3 ]

(b)

Predict the number of ${ }^{1} \mathrm{H} \mathrm{NMR}$ signals, and splitting pattern of the $-\mathrm{CH}_{3}$ seen for propanone $\left(\mathrm{CH}_{3} \mathrm{COCH}_{3}\right)$ and propanal $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHO}\right)$ .

[ 2 ]

(c)

Predict the fragment that is responsible for a m / z of 31 in the mass spectrum of propan-1-ol. Use section 28 of the data booklet.

[ 1 ]

[Maximum number: 14]

The mass spectrum and infrared (IR) spectrum of a compound are shown below.

(a)

(i)

State the information about this particular compound that can be derived from the mass spectrum and outline how it is found.

[ 2 ]

(ii)

Suggest how the fragment with m / z=43 is formed from the original molecule.

[ 1 ]

(b)

(i)

Use the IR spectrum in the region $1600-1800 \mathrm{~cm}^{-1}$ to deduce one functional group that is present in the compound and one group that is absent.

Present:
Absent:

[ 2 ]

(ii)

The molecular formula of the compound is $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}_{2}$ . Explain, with reference to another region of the IR spectrum, why the compound could not be propanoic acid, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}$ .

[ 2 ]

(iii)

Deduce the structures of two possible isomers of propanoic acid consistent with the IR spectrum.

[ 2 ]

(c)

${ }^{1}$ HNMR spectroscopy is often very useful in distinguishing between closely related compounds such as the ones shown below.

Deduce the ${ }^{1}$ HNMR spectra you would expect for each compound and complete the table below. (The answers for propanoic acid are given as a guide.)

Note that some of the boxes may be blank.

[ 5 ]

[Maximum number: 1]

Methanoic acid (HCOOH) is the first member of the homologous series of carboxylic acids.

(a)

Outline what is meant by the term "homologous series".

[ 1 ]

[Maximum number: 5]

Ethyne, $\mathrm{C}_{2} \mathrm{H}_{2}$ , reacts with oxygen in welding torches.

(a)

Ethyne reacts with steam.

\mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{~g}) \rightarrow \mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}(\mathrm{~g})

Two possible products are:

[ 5 ]

(i)

State the name of product B, applying IUPAC rules.

[ 1 ]

(ii)

The IR spectrum and low resolution ${ }^{1} \mathrm{HNMR}$ spectrum of the actual product formed are shown.

$\({$

\({

Deduce whether the product is A or B, using evidence from these spectra together with sections 26 and 27 of the data booklet.

Identity of product:

One piece of evidence from IR:

One piece of evidence from ${ }^{1} \mathrm{H} \mathrm{NMR}$ :

[ 2 ]

(iii)

Deduce the splitting pattern you would expect for the signals in a high resolution ${ }^{1}$ HNMR spectrum.
2.3 ppm :
9.8 ppm:

[ 2 ]

[Maximum number: 8]

Infrared (IR) spectroscopy is a powerful analytical technique.

(a)

Describe how information from an IR spectrum can be used to identify the bonds in a molecule.

[ 2 ]

(b)

Explain which of the following compounds would produce the IR spectrum below by referring to the wavenumbers of the relevant peaks found in table 17 of the data booklet.
$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH}$ $\mathrm{CH}_{3} \mathrm{COOCH}_{2} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{3}$
Compound B

\begin{gathered} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH} \\ \text { Compound } \mathbf{C} \end{gathered}

$Compound \(\mathbf{A$

Compound \(\mathbf{A

[ 3 ]

(c)

Explain how the low resolution ${ }^{1} \mathrm{H}$ NMR spectra of the three compounds in part (b) can be used to distinguish between them. Ignore chemical shifts.

[ 3 ]

[Maximum number: 8]

Analytical techniques are very useful in determining molecular structures. A compound, X, has the empirical formula $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$ .

(a)

Identify the analytical technique that would most readily provide the additional data required to calculate the molecular formula of X.

[ 1 ]

(b)

The molecular formula of X is $\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}$ . The information in the IR spectrum below can be used to help determine the structure of X.

[ 3 ]

(i)

Deduce the information obtained from absorptions A and B.

A:

B:

[ 2 ]

(ii)

Comment on the absence of any major absorption in the region 1700-1750 cm-1.

[ 1 ]

(c)

The ${ }^{1} \mathrm{HNMR}$ spectrum of X shows three peaks with relative areas of 2: 1: 1.

[ 4 ]

(i)

Deduce what information can be obtained from these data.

[ 2 ]

(ii)

Deduce the structure of X.

[ 2 ]

(a)

Draw the two possible structures of compound P.

[ 1 ]

(b)

Explain why the infrared spectra of the structures in (a) are very similar.

[ 1 ]

(c)

Pentan-2-one has the following mass spectrum.

Deduce the formulas of the species with the m / z values at 71 and 43 .
m / z=71:
m / z=43:

[ 2 ]

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