[Maximum number: 2]

Species such as $\mathrm{NH}_{4}{ }^{+}, \mathrm{CO}_{3}{ }^{2-}$ and $\mathrm{PO}_{4}{ }^{3-}$ are examples of molecular ions.

(a)

$\mathrm{NH}_{4}{ }^{+}$ is a Brønsted-Lowry acid.

[ 2 ]

(i)

The nitrogen atom in $\mathrm{NH}_{4}{ }^{+}$ is $\mathrm{sp}^{3}$ hybridised. $\mathrm{sp}^{3}$ orbitals form from the mixing of one 2 s and three 2 p orbitals.

Sketch the shapes of a 2 s and a $2 p_{x}$ orbital on the axes in Fig. 1.1.

Fig. 1.1

[ 2 ]

[Maximum number: 1]

When considering one molecule of ethene, which row describes both the hybridisation of the atomic orbitals in the carbon atoms and the overall bonding?

hybridisation

bonding

$\mathrm{sp}^{2}$

$4 \sigma$ bonds $1 \pi$ bond

$\mathrm{sp}^{2}$

$5 \sigma$ bonds $1 \pi$ bond

$\mathrm{sp}^{3}$

$4 \sigma$ bonds $1 \pi$ bond

$\mathrm{sp}^{3}$

$5 \sigma$ bonds $1 \pi$ bond

[Maximum number: 1]

Which molecule contains a nitrogen atom with sp hybridised orbitals?

A

$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2}$

B

$\mathrm{HNO}_{3}$

C

HCN

D

$\mathrm{NH}_{3}$

[Maximum number: 1]

The molecular formula $\mathrm{C}_{3} \mathrm{H}_{6}$ represents the compounds propene and cyclopropane.

propene

cyclopropane

(a)

What is the H-C-H bond angle at the terminal $=\mathrm{CH}_{2}$ group in propene?

[ 1 ]

[Maximum number: 1]

The formula $\mathrm{CH}_{3}$ can represent an anion, a cation or a free radical. Species with the molecular formula $\mathrm{CH}_{3}$ can act as an electrophile, a free radical or a nucleophile depending on the number of outer shell electrons on the central carbon atom.

How many outer shell electrons must be present for $\mathrm{CH}_{3}$ to act in these different ways?

$\mathrm{CH}_{3}$ as an

electrophile

$\mathrm{CH}_{3}$ as a

free radical

$\mathrm{CH}_{3}$ as a

nucleophile

6

7

8

6

8

7

6

8

7

6

[Maximum number: 1]

The diagram shows a molecule that has $\sigma$ bonds and $\pi$ bonds.

How many $\sigma$ bonds are present in this molecule?

A

15

B

17

C

18

D

21

[Maximum number: 1]

Poly(propene) is an addition polymer.
What are the C-C-C bond angles along its polymer chain?

A

They are all $109^{\circ}$ .

B

Half of them are $109^{\circ}$ and half are $120^{\circ}$ .

C

Half of them are $90^{\circ}$ and half are $180^{\circ}$ .

D

They are all $120^{\circ}$ .

(a)

Hydrogen cyanide, HCN , is a weak acid in aqueous solution.

\mathrm{HCN}(\mathrm{aq}) \rightleftharpoons \mathrm{H}^{+}(\mathrm{aq})+\mathrm{CN}^{-}(\mathrm{aq}) \quad K_{\mathrm{a}}=6.2 \times 10^{-10} \mathrm{moldm}^{-3}

[ 2 ]

(i)

State the hybridisation of the carbon and nitrogen atoms in hydrogen cyanide, and give the H-C-N bond angle.
hybridisation of C
hybridisation of N
H-C-N bond angle

[ 2 ]

[Maximum number: 1]

High-energy radiation in the stratosphere produces free-radicals from chlorofluoroalkanes, commonly known as CFCs.

Which free-radical is most likely to result from the irradiation of $\mathrm{CHFClCF}_{2} \mathrm{Cl}$ ?

A

CHFClĊFCl

B

$\dot{\mathrm{C}} \mathrm{HClCF}_{2} \mathrm{Cl}$

C

$\dot{\mathrm{C}} \mathrm{HFCF}_{2} \mathrm{Cl}$

D

$\dot{\mathrm{C}} \mathrm{FClCF}_{2} \mathrm{Cl}$

[Maximum number: 1]

The molecular formula $\mathrm{CH}_{3}$ can represent an anion, a cation or a free radical. Species with the molecular formula $\mathrm{CH}_{3}$ can act as an electrophile, a free radical or a nucleophile depending on the number of outer shell electrons on the central carbon atom.

How many outer shell electrons on the central carbon atom must be present for $\mathrm{CH}_{3}$ to act in these different ways?

$\mathrm{CH}_{3}$ as an

electrophile

$\mathrm{CH}_{3}$ as a

free radical

$\mathrm{CH}_{3}$ as a

nucleophile

6

7

8

6

8

7

6

8

7

6

Question 1

Question 1(c)

Question 1(c)(iii)

Question 3

Question 4

Question 2

Question 2(a)

Question 20

Question 21

Question 24

Question 3

Question 3(a)

Question 3(a)(iii)

Question 26

Question 27