Chemistry 2021 Oct/Nov | Past Paper Questions & Answers

Q1.

Short Answer 1 mark

Hydrogen iodide, HI, is a colourless gas at room temperature.

Q1(a).

Short Answer 1 mark

(i) Explain why HI has a higher boiling point than HCl and HBr.

Q1(ii).

Short Answer 1 mark

The bar chart shows the boiling points of HCl, HBr and HI. The boiling point of HF is not shown. boiling point / K HF HCl HBr HI Hydrogen bonds form between HF molecules. Draw a bar on the bar chart to predict the boiling point of HF. Explain your answer. Define the term standard enthalpy change of formation .

Q1(c).

Short Answer 1 mark

HI

Q1(c)(g).

Short Answer 1 mark

can be formed by reacting H

Q1(g).

Short Answer 1 mark

with I

Q1(g).

Short Answer 1 mark

The reaction is reversible, and an equilibrium forms quickly at high temperatures.

Q1(g).

Short Answer 1 mark

2HI(g)

Q1(i).

Short Answer 1 mark

Construct an expression for the equilibrium constant, K , for the reaction of H

Q1(g).

Short Answer 1 mark

and I

Q1(g).

Short Answer 1 mark

to form HI(g).

Q1(g).

Short Answer 1 mark

HI

Q1(g)(g).

Short Answer 1 mark

Calculate K for this reaction. =

Q1(iii).

Short Answer 1 mark

State how the value of K Explain your answer.

Q1(d).

Short Answer 1 mark

HI reacts with oxygen to form iodine and water.

Q1(i).

Short Answer 1 mark

Construct an equation for the reaction of HI with oxygen.

Q1(ii).

Short Answer 1 mark

Explain, with reference to oxidation numbers, why this reaction is a redox reaction.

Q1(e).

Short Answer 1 mark

HI

Q1(e)(g).

Short Answer 1 mark

can also be formed by the reaction of I

Q1(g).

Short Answer 1 mark

with hydrazine, N

Q1(g).

Short Answer 1 mark

in a sealed container at constant temperature. Explain your answer.

Q1(f).

Short Answer 1 mark

In the laboratory, HI(aq) can be formed in a two-step process. step 1 3I

Q1(s).

Short Answer 1 mark

step 2 PI

Q1(aq).

Short Answer 1 mark

+ 3HI(aq)

Q1(i).

Short Answer 2 marks

Draw a 'dot-and-cross' diagram of a PI molecule.

Q1(ii).

Short Answer 1 mark

Name the type of reaction in step 2.

Q1(aq).

Short Answer 1 mark

and HI(aq) are both strong Brønsted-Lowry acids. Give the meaning of the term strong Brønsted-Lowry acid .

Q1(iv).

Short Answer 1 mark

Give the formula of the conjugate base of H

Q1(g).

Short Answer 1 mark

HI

Q1(g)(g).

Short Answer 1 mark

reacts with propene, CH CH=CH

Q1(g).

Short Answer 1 mark

to form a mixture of 1-iodopropane and 2-iodopropane.

Q1(i).

Short Answer 1 mark

Identify which of 1-iodopropane and 2-iodopropane is the major product of this reaction. Explain your answer.

Q1(ii).

Short Answer 1 mark

Complete the diagram to show the mechanism of the reaction between HI and CH CH=CH that forms the major product identified in (g)(i). Include curly arrows, lone pairs of electrons and charges as necessary. + - [3] [Total: 26]

Q2(a).

Short Answer 1 mark

Table 1 gives physical data for some of the Period 3 elements. Table 1 atomic number, Z 11 12 13 14 15 16 17 bonding present in element M C 494 736 577 786 106010001260 maximum oxidation number +7

Q2(i).

Short Answer 1 mark

Complete the row in the table labelled 'bonding present in element'. Use C = covalent, I = ionic, M = metallic, as appropriate.

Q2(ii).

Short Answer 1 mark

Explain the difference between the first ionisation energies of the elements with atomic numbers 11 and 17.

Q2(iii).

Short Answer 1 mark

Explain the difference between the first ionisation energies of the elements with atomic numbers 15 and 16.

Q2(iv).

Short Answer 1 mark

Complete the row in the table labelled 'maximum oxidation number'.

Q2(v).

Short Answer 1 mark

Explain the variation in anionic radius for the elements with atomic numbers 14 to 17.

Q2(b).

Short Answer 2 marks

Use the axes to sketch a graph that shows the trend in melting points of the elements with atomic numbers 11 to 17. 11121314151617 atomic number, Z melting point of element

Q2(c).

Short Answer 3 marks

Dmitri Mendeleev published the first Periodic Table in 1869. Mendeleev used his knowledge of chemical periodicity to propose the properties of gallium, Ga, a Group 13 element. Table 2 gives some chemical and physical data of elements in Group 13. Table 2 element density boiling point cationic radius B 2.34 3930 0.020 Al 2470 0.050 Ga 5.91 2400 In 7.30 0.081 Tl 11.8 1460 0.095 Complete the table by predicting values for the missing data.

Q2(d).

Short Answer 1 mark

Indium and aluminium are elements in Group 13 of the Periodic Table. Indium has very similar chemical properties to aluminium. solution. , is amphoteric. . This molecule contains coordinate bonds.

Q2(i).

Short Answer 1 mark

Identify the formula of the salt formed when indium reacts with hydrochloric acid.

Q2(ii).

Short Answer 1 mark

Construct an equation for the reaction of In with excess aqueous NaOH.

Q2(iii).

Short Answer 1 mark

Draw a diagram that clearly shows the types of bond present in In

Q2(g).

Short Answer 1 mark

[2] [Total: 17]

Q3.

Short Answer 1 mark

Compound T is an isomer of C

Q3(a).

Short Answer 1 mark

Name T.

Q3(b).

Short Answer 1 mark

Draw the skeletal formula of a structural isomer of T that shows cis-trans (geometrical) isomerism.

Q3(c).

Short Answer 1 mark

Each carbon atom in T forms a sigma (σ) bond to at least one other carbon atom, as shown.

Q3(i).

Short Answer 1 mark

On the diagram, draw the orbitals that represent the pi (π) bond that is also present in T.

Q3(ii).

Short Answer 1 mark

State the hybridisation of the two carbon atoms between which the pi (π) bond forms.

Q3(d).

Short Answer 1 mark

A reaction scheme starting with T is shown. Reaction 2 occurs in the presence of a catalyst; knowledge of the mechanism for this reaction is not required.T U reaction 1 reaction 2 catalyst HO OH

Q3(i).

Short Answer 1 mark

Give the reagent

Q3(i)(s).

Short Answer 1 mark

and conditions for reaction 1.

Q3(ii).

Short Answer 1 mark

State and explain how 2,4-dinitrophenylhydrazine (2,4-DNPH) can be used to detect the presence of V as a product of reaction 2.

Q3(iii).

Short Answer 2 marks

The progress of reaction 2 can be monitored by infrared spectroscopy. The absorption caused by O-H bonds is always present because water is used as a solvent. Identify two absorptions, and the bonds responsible for these absorptions, whose appearance will change significantly during the reaction. 1 2

Q3(e).

Short Answer 1 mark

V is used in a wide range of organic reactions. Some reactions of V are shown. reaction 3 reaction 4NaBH alkaline aqueous I reaction 5 reaction 6 dehydration addition polymerisation

Q3(i).

Short Answer 1 mark

V and W are colourless and soluble in water. State what you would observe in reaction 3. Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every UHDVRQDEOHH?RUWKDVEHHQPDGHE\WKHSXEOLVKHU8&/(6WRWUDFHFRS\ULJKWKROGHUVEXWLIDQ\LWHPVUHTXLULQJFOHDUDQFHKDYHXQZLWWLQJO\EHHQLQFOXGHGWKH publisher will be pleased to make amends at the earliest possible opportunity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

Q3(ii).

Short Answer 1 mark

Reaction 3 is a redox reaction. Identify which of the reactants is reduced in this reaction.

Q3(iii).

Short Answer 1 mark

Construct an equation for reaction 4. Use [H] in the equation to represent an atom of hydrogen from NaBH

Q3(iv).

Short Answer 2 marks

X is a mixture of two optical isomers. Draw the two optical isomers in the boxes provided.

Q3(v).

Short Answer 1 mark

Both optical isomers of X can be dehydrated to form a single product, Y. Give the reagent

Q3(v)(s).

Short Answer 1 mark

and conditions required for reaction 5.

Q3(vi).

Short Answer 1 mark

Y can form an addition polymer Z. Draw one repeat unit of Z.

Q3(vii).

Short Answer 1 mark

Reaction 6 does not proceed quickly at room temperature. Suggest why this is the case. [Total: 17]

CAIE Chemistry (9701)

Questions & Answers

CAIE Chemistry `(9701)`