3 3
(i) Write the expression for the acid dissociation constant, K , for carbonic acid.
a
State symbols are not required.
(1)
(ii) A blood sample taken from an individual was analysed.
Calculate the pH of the blood sample.
Use your expression for K and the values shown.
a
K for carbonic acid = 4.50 × 10−7 mol dm−3
a
[HCO–] = 0.0240 mol dm−3 [H CO ] = 0.00200 mol dm−3
Question
Mathematics
Edexcel2024
Explain the differences in these values.
(4)
Experimental lattice energy Theoretical lattice energy
Compound
/ kJ mol−1 / kJ mol−1
MgF −2957 −2913 2
MgI −2327 −1944 2
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(Total for Question 8 = 12 marks)
Question
Mathematics
Edexcel2024
Use your Data Booklet.
2VO+(aq) + 4H+(aq) + Zn(s) → 2VO2+(aq) + 2H O(l) + Zn2+(aq)
Question
Mathematics
Edexcel2024
D VO2+ blue +5
(d) What is the value of the cell potential for the reaction of Zn and VO+ ?
Question
Mathematics
Edexcel2024
Question
Mathematics
Edexcel2024
2 2 3
Equilibrium 2 H CO (aq) H+(aq) + HCO−(aq)
Question
Mathematics
Edexcel2024
4
propanoic acid CH CH COOH 2.94
Question
Mathematics
Edexcel2024
2 3
The mean titre was 14.40 cm3 .
2S O2–(aq) + I (aq) → 2I–(aq) + S O2−(aq)
Question
Mathematics
Edexcel2024
2
(1)
A +1.76 V
B +0.24 V
C −0.24 V
D −1.76 V
(Total for Question 7 = 6 marks)
*P76895A01828*
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(cid:44)(cid:1)(cid:1)(cid:1)(cid:1)(cid:9)(cid:1)(cid:1)(cid:1)(cid:1)(cid:1)(cid:1)(cid:3)(cid:2)(cid:44)
(b) Many zoos around the world operate captive breeding programmes for the red ruffed lemur.
Fig. 9.2 shows the numbers of captive‑born red ruffed lemurs in North American zoos from
1970 to 2020.
200
150
number of
captive-born 100
red ruffed lemurs
Question
Mathematics
Edexcel2024
This question is about the formation of ions.
(a) Explain the trend in the values of the first electron affinities of the
elements shown.
(4)
Element First electron affinity / kJ mol−1
chlorine −349
bromine −325
iodine −295
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(b) Which of these isoelectronic ions has the smallest ionic radius?
(1)
A S2−
B Cl−
C K+
D Ca2+
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(c) Some series of successive ionisation energies in kJ mol−1 are shown.
The letters do not refer to the symbols of the elements.
Element Successive ionisation energies / kJ mol−1
A 578 1817 2745 11 578 14 831
B 653 1592 2987 4740 6686
C 738 1451 7733 10 541 13 629
D 1086 2353 4621 6223 37 832
(i) Which element in the table could be in Group 4?
(1)
A
B
C
D
(ii) Which element in the table could be described as an s-block element?
(1)
A
B
C
D
(Total for Question 2 = 7 marks)
Question
Mathematics
Edexcel2024
4
solution of concentration 0.0450 mol dm−3?
The molar mass of K SO is 174.3 g mol−1.
Question
Mathematics
Edexcel2024
4
(1)
A 1.96 g
B 7.84 g
C 19.6 g
D 31.4 g
(Total for Question 3 = 10 marks)
Question
Mathematics
Edexcel2024
2
Question
Mathematics
Edexcel2024
2
Question
Mathematics
Edexcel2024
3 2 4 6
(i) State the indicator used in this titration, giving the colour change that would
be observed at the end-point.
(2)
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Question
Mathematics
Edexcel2024
2
(ii) Calculate the value of Δ H [MgF (s)].
f 2
(1)
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(iii) The experimental and theoretical values of the lattice energy for MgF and
Question
Mathematics
Edexcel2024
C
A
Mg(s) + F (g) MgF (s)
Question
Mathematics
Edexcel2024
3 3
(i) When a person exercises vigorously the concentration of carbon dioxide (aq)
in the blood increases.
Explain how this increase in the concentration of carbon dioxide affects the
pH of the blood.
Refer to the equilibria in your answer. No calculation is required.
(2)
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(ii) Explain how the carbonic acid–hydrogencarbonate buffer system in
Equilibrium 2 acts to restore the pH of the blood after a person has exercised.
(2)
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(Total for Question 4 = 14 marks)
Question
Mathematics
Edexcel2024
5 2 2 2
(a) Calculate the enthalpy change for the reaction using the
mean bond enthalpy data.
(3)
Bond Mean bond enthalpy / kJ mol−1
C C 347
C H 413
C O 358
O H 464
O O 498
C O 805
Enthalpy change = kJ mol−1
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(b) (i) Complete the enthalpy cycle for the overall reaction in the Direct Ethanol
Fuel Cell. Include labels.
(2)
Substance Δ H / kJ mol−1
f
C H OH(l) −277
Question
Mathematics
Edexcel2024
5
CO (g) −394
Question
Mathematics
Edexcel2024
H O(l) −286
Question
Mathematics
Edexcel2024
Δ H
r
C H OH(l) + 3O (g) 3H O(l) + 2CO (g)
Question
Mathematics
Edexcel2024
5 2 2 2
(ii) Calculate a value for the enthalpy change of the Direct Ethanol Fuel Cell
reaction, using your cycle.
(1)
Enthalpy change = kJ mol−1
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Question
Mathematics
Edexcel2024
5
The equation for the second stage is shown.
SO (g) + ½O (g) SO (g) ΔH = −196 kJ mol−1
Question
Mathematics
Edexcel2024
2 3
(a) (i) What are the expression and the units for the equilibrium constant (K ) for
p
this reaction?
(1)
Expression Units
p(cid:31)SO (cid:30)
A 3 atm2
p(cid:31)SO (cid:30)p(cid:31)O (cid:30)½
Question
Mathematics
Edexcel2024
2
p(cid:31)SO (cid:30)p(cid:31)O (cid:30)½
B 2 2 atm½
p(cid:31)SO (cid:30)
Question
Mathematics
Edexcel2024
2
(ii) Which variable affects the value of K ?
p
(1)
A pressure
B temperature
C surface area of the catalyst
D concentration of O (g)
Question
Mathematics
Edexcel2024
5
State symbols are not required.
(2)
(c) Which row of the table shows the correct colour of the solution and oxidation
number of vanadium in the aqueous ions shown?
(1)
Oxidation number
Aqueous ion Colour of solution
of vanadium
A VO+ yellow +3
Question
Mathematics
Edexcel2023
6
I Cl ICl+ + ICl–
Question
Mathematics
Edexcel2023
6
When molten, it is suggested that it breaks down as shown.
I Cl ICl+ + ICl–
Question
Mathematics
Edexcel2023
3
Ionisation
energy
Question
Mathematics
Edexcel2023
2
Question
Chemistry
CAIE2023
The table shows some information about three particles, A, B and C.
Particle | protons | neutrons | electrons
A | 8 | 8 | 10
B | 17 | 18 | 18
C | 11 | 12 | 11
(a) Identify particle A, giving its full symbol including charge.
(b) State the relationship between particles A and B.
(c) Which particle is a neutral atom? Give a reason for your answer.
[4 marks]
Mathematics
Edexcel2023
6 2 4
What is the most likely numerical value of K for this equilibrium?
c
(1)
A 1.0 × 106
B 5.0 × 103
C 1.0
D 5.0 × 10–3
(Total for Question 3 = 9 marks)
Question
Mathematics
Edexcel2023
*P71912A0228*
PMT
Answer ALL questions.
Some questions must be answered with a cross in a box . If you change your mind about an
answer, put a line through the box and then mark your new answer with a cross .
Question
Mathematics
Edexcel2023
(ii) Using oxidation numbers, deduce the molar ratio of MnO – to Cl– that would
Question
Mathematics
Edexcel2023
2 3 2
Using oxidation numbers, explain why the chlorine in ClO has undergone
Question
Chemistry
Edexcel2023
Magnesium has three naturally occurring isotopes: ²⁴Mg, ²⁵Mg and ²⁶Mg.
(a) Explain what is meant by the term isotopes.
(b) The percentage abundances of ²⁴Mg and ²⁵Mg are 79.0% and 10.0% respectively. Calculate the relative atomic mass of magnesium, giving your answer to 3 significant figures.
[4 marks]
Mathematics
Edexcel2023
Chlorine and bromine are elements in Group 7 of the Periodic Table.
Both elements exist in a number of different oxidation numbers and therefore are
involved in many redox reactions.
(a) Write an equation for the reaction between chlorine and cold, dilute aqueous
sodium hydroxide. State symbols are not required.
(1)
(b) Chlorine dioxide reacts with cold, dilute aqueous sodium hydroxide.
The ionic equation for the reaction is:
2ClO (aq) + 2OH−(aq) → ClO –(aq) + ClO –(aq) + H O(l)
Question
Mathematics
Edexcel2023
2
Question
Mathematics
Edexcel2023
Chemists often use the term ‘orbital’ when considering atomic structure.
(a) State what is meant by the term orbital.
(2)
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(b) Draw diagrams to show the shape of an s and a p orbital.
(2)
s orbital p orbital
(c) What is the electronic configuration of a copper atom?
(1)
A [Ar]4s13d10
B [Ar]4s23d9
C [Ar]4s24p13d8
D [Ar]4s24p23d7
(Total for Question 2 = 5 marks)
Question
Mathematics
Edexcel2023
6 2 4
(i) Draw a labelled diagram of a simple experiment to confirm this dissociation
has occurred, stating the positive result.
(2)
Result
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(ii) What is the shape of the ICl– ion?
Question
Mathematics
Edexcel2023
4 2
colourless brown
(a) The table shows values of ΔG at different temperatures for this reaction.
Temperature / K ΔG / kJ mol–1
350 –4.0
400 –13
450 –22
500 –31
550 –40
(i) Plot a graph of ΔG against temperature.
(2)
ΔG / kJ mol–1
Temperature / K