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OCR A Level Chemistry

Topic questions Bonding, structure and the properties of matter Electronegativity & bond polarity

Electronegativity & bond polarity

6 questions · 25 marks · about 35 minutes

Electronegativity and bond polarity questions

TopicElectronegativity & bond polarity

OCR H432 Electronegativity and bond polarity 6 questions

Periodic table, elements and physical chemistry June 2024, Question 18 12 marks

This question is about two oxides of sulfur: sulfur dioxide, SO2, and sulfur trioxide, SO3.

(a)

SO3 decomposes to form SO2 and O2, as shown in Equilibrium 18.1.

Question 18, shown as an image
(a)(i)

2.25 moles of SO3 is heated to 550 maths symbolC in the presence of a catalyst and the resulting mixture allowed to reach equilibrium.

The equilibrium mixture contains 0.900 mol of SO2 and the total pressure is 2.80 atm.

Calculate the numerical value for Kp for Equilibrium 18.1 under these conditions and state the units of Kp.

Give your answer to 3 significant figures.

[5]
Reveal mark scheme Mark scheme for question 18(a)(i)
(a)(ii)

The numerical values of Kp for Equilibrium 18.1 at temperatures T1 and T2 are shown below.

TemperatureKp
T13.3 × 10–5
T27.7 × 10–2

Explain why T2 is a higher temperature than T1.

[2]
Reveal mark scheme Mark scheme for question 18(a)(ii)
(a)(iii)

Suggest how the value of Kp would change if the reaction was repeated with no catalyst added and the pressure of the system increased.

Tick (✓) one box in each row.

Figure for question 18
[2]
Reveal mark scheme Mark scheme for question 18(a)(iii)
(b)

SO2 and SO3 both have molecules with sulfur in the centre and bond angles of approximately 120maths symbol.

Reveal mark scheme Mark scheme for question 18(b)
(b)(i)

Explain why the bond angles in SO3 are 120maths symbol.

[1]
Reveal mark scheme Mark scheme for question 18(b)(i)
(b)(ii)

Explain why both SO2 and SO3 have polar bonds, but only SO2 has polar molecules.

[2]
Reveal mark scheme Mark scheme for question 18(b)(ii)

Periodic table, elements and physical chemistry November 2021, Question 1 1 mark

Which statement describes electronegativity?

A A measure of the reactivity of an element.

B The ability of an atom to attract an electron to become a 1– ion.

C The attraction of a bonded atom for the electrons in a covalent bond.

D The attraction of an atom for a lone pair of electrons.

Your answer

[1]
Reveal mark scheme Mark scheme for question 1

Periodic table, elements and physical chemistry November 2021, Question 14 1 mark

Which statement(s) about a molecule of C l –N=O is/are correct?

1: It is a polar molecule.

2: It contains 6 lone pairs of electrons.

3: It has a bond angle of 180°.

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Your answer

[1]
Reveal mark scheme Mark scheme for question 14

Unified chemistry June 2019, Question 1 9 marks

These short questions are from different areas of chemistry.

(a)

Explain why a CF4 molecule has polar bonds but does not have an overall dipole.

[2]
Reveal mark scheme Mark scheme for question 1(a)
(b)

Explain why a small proportion of molecules in water have a relative molecular mass of 20.

[1]
Reveal mark scheme Mark scheme for question 1(b)
(c)

What is the partial pressure of O2 (in Pa) in a gas mixture containing 21% O2 by volume and with a total pressure of 1.0 × 105 Pa?

[1]
Reveal mark scheme Mark scheme for question 1(c)
(d)

What mass of carbon dioxide (in g) is formed by the complete combustion of 42.0 m3 (measured at RTP) of propane?

[2]
Reveal mark scheme Mark scheme for question 1(d)
(e)
Figure for question 1 Figure for question 1
[1]
Reveal mark scheme Mark scheme for question 1(e)
(f)

What is the number of oxygen atoms in 4.26 g of P2O5?

[2]
Reveal mark scheme Mark scheme for question 1(f)

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