Question paper (A-level) : Paper 2 Organic and physical chemistry ...

Please write clearly in block capitals. Centre number

Candidate number

Surname Forename(s) Candidate signature

I declare this is my own work.

A-level CHEMISTRY

Paper 2 Organic and Physical Chemistry

Monday 8 June 2020

Afternoon

Time allowed: 2 hours

Materials For this paper you must have: ? the Periodic Table/Data Booklet, provided as an insert (enclosed) ? a ruler with millimetre measurements ? a scientific calculator, which you are expected to use where appropriate.

Instructions ? Use black ink or black ball-point pen. ? Fill in the boxes at the top of this page. ? Answer all questions. ? You must answer the questions in the spaces provided. Do not write outside

the box around each page or on blank pages. ? If you need extra space for your answer(s), use the lined pages at the end of

this book. Write the question number against your answer(s). ? All working must be shown. ? Do all rough work in this book. Cross through any work you do not want to

be marked.

For Examiner's Use

Question 1 2 3 4 5 6 7 8 9

TOTAL

Mark

Information ? The marks for questions are shown in brackets. ? The maximum mark for this paper is 105.

*JUN207405201*

IB/M/Jun20/E11

7405/2

0 1

2 Answer all questions in the spaces provided.

Do not write outside the

box

This question is about rates of reaction.

Phosphinate ions (H2PO2?) react with hydroxide ions to produce hydrogen gas as shown.

H2PO2? + OH- HPO32? + H2

A student completed an experiment to determine the initial rate of this reaction. The student used a solution containing phosphinate ions and measured the volume of hydrogen gas collected every 20 seconds at a constant temperature. Figure 1 shows a graph of the student's results.

Figure 1

0 1.1

Use the graph in Figure 1 to determine the initial rate of reaction for this experiment. State its units. Show your working on the graph.

[3 marks]

Rate

*02*

Units

IB/M/Jun20/7405/2

3

0 1.2

Another student reacted different initial concentrations of phosphinate ions with an

excess of hydroxide ions. The student measured the time (t) taken to collect 15 cm3 of hydrogen gas. Each experiment was carried out at the same temperature.

Table 1 shows the results.

Table 1

Do not write outside the

box

Initial [H2PO2?] / mol dm?3

t / s

0.25

64

0.35

32

0.50

16

1.00

4

State the relationship between the initial concentration of phosphinate and time (t).

Deduce the order of the reaction with respect to phosphinate.

Relationship Order

[2 marks]

Question 1 continues on the next page

*03*

Turn over

IB/M/Jun20/7405/2

4

0 1.3

Complete the diagram in Figure 2 to show how the hydrogen gas could be collected and measured in the experiments in Questions 01.1 and 01.2.

[1 mark]

Do not write outside the

box

Figure 2

The rate equation for a different reaction is rate = k [L] [M]2

0 1.4

Deduce the overall effect on the rate of reaction when the concentrations of both L and M are halved.

[1 mark]

*04*

IB/M/Jun20/7405/2

5

0 1 . 5 The rate of reaction is 0.0250 mol dm?3 s?1 when the concentration of L is 0.0155 mol dm?3

Do not write outside the

box

Calculate the concentration of M if the rate constant is 21.3 mol?2 dm6 s?1 [3 marks]

Concentration of M 0 1 . 6 Define the term overall order of reaction.

Turn over for the next question

mol dm?3 [1 mark]

11

*05*

Turn over

IB/M/Jun20/7405/2

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download