DP Chemistry (last assessment 2024)

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Question 17N.2.hl.TZ0.2

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Date November 2017 Marks available [Maximum mark: 13] Reference code 17N.2.hl.TZ0.2
Level hl Paper 2 Time zone TZ0
Command term Calculate, Deduce, Determine, Outline, State Question number 2 Adapted from N/A
2.
[Maximum mark: 13]
17N.2.hl.TZ0.2

Analytical chemistry uses instruments to separate, identify, and quantify matter.

(b)

Outline how this spectrum is related to the energy levels in the hydrogen atom.

[1]

Markscheme

electron transfer/transition between high«er» energy level to low«er» energy level

OR

electron transitions into first energy level causes UV series

OR

transition into second energy level causes visible series

OR

transition into third energy level causes infrared series

Accept any of the points shown on a diagram.

(c)

A sample of magnesium has the following isotopic composition.

Calculate the relative atomic mass of magnesium based on this data, giving your answer to two decimal places.

[2]

Markscheme

24 x 0.786 + 25 x 0.101 + 26 x 0.113

24.33

Award [2] for correct final answer.
Award [0] for 24.31 with no working (data booklet value).

Menthol is an organic compound containing carbon, hydrogen and oxygen.

(d.i)

Complete combustion of 0.1595 g of menthol produces 0.4490 g of carbon dioxide and 0.1840 g of water. Determine the empirical formula of the compound showing your working.

[3]

Markscheme

carbon: « 0.4490 g 44.01 g mo l − 1 =» 0.01020 «mol» / 0.1225 «g»
OR
hydrogen: « 0.1840 × 2 18.02 g m o l − 1 =» 0.02042 «mol» / 0.0206 «g»

oxygen: «0.1595 – (0.1225 + 0.0206)» = 0.0164 «g» / 0.001025 «mol»

empirical formula: C10H20O

Award [3] for correct final answer.

Do not award M3 for a hydrocarbon.

(d.ii)

0.150 g sample of menthol, when vaporized, had a volume of 0.0337 dm3 at 150 °C and 100.2 kPa. Calculate its molar mass showing your working.

[2]

Markscheme

«temperature =» 423 K
OR
M = m R T p V

«M  = 0.150 g × 8.31 J K − 1 mol − 1 × 423 K 100.2 kPa × 0.0337 d m 3 = » 156 «g mol–1»

Award [1] for correct answer with no working shown.

Accept “pV = nRT AND n =  m M ” for M1.

(d.iii)

Determine the molecular formula of menthol using your answers from parts (d)(i) and (ii).

[1]

Markscheme

C10H20O

[1 Mark]

Nitric oxide reacts with chlorine.

2NO (g) + Cl2 (g) → 2NOCl (g)

The following experimental data were obtained at 101.3 kPa and 263 K.

(e.i)

Deduce the order of reaction with respect to Cl2 and NO.

[2]

Markscheme

Cl2: first
NO: second

(e.ii)

State the rate expression for the reaction.

[1]

Markscheme

rate = k [NO]2 [Cl2]

(e.iii)

Calculate the value of the rate constant at 263 K.

[1]

Markscheme

180 / 1.80 x 102 «dm6 mol–2 min–1»

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