Practice Examination paper
School of Life and Environmental Sciences
Trimester 1
Unit Code: SLE210
Unit Name: Chemistry the Enabling Science
Paper name: Exam paper 1
Wave and particle properties of electron 10 mark
Q1. Microwave ovens use radiation with wavelength of 12.5 cm. What is the frequency, and energy in kJ/mol, of this radiation? 5 mark
Q2. List all possible quantum sets for an electron in the 4p quantum level. 5 mark
Chemical bonding and molecular structure 10 mark
Q3. Capsaicin is the molecule responsible for the hot spiciness of chillies:
Using your knowledge of valence bond theory please answer the following:
a. How many π bonds does capsaicin have? 1 mark
b. Which orbitals are used for bonding by each of the labelled atoms? 5 mark
c. What are the bond angles around each of the labelled atoms? 1 mark
Q4. Which of N2 or N2+ has the stronger bond? Use molecular orbital configurations (molecular orbital theory) to justify your selection. 3 mark
Transition metals and their complexes 10 mark
Q5. Why is manganese(VII) [in potassium permanganate] intensely coloured while manganese(II) is generally not? 5 mark
Q6. How can complexation be used for gold mining? 5 mark
Electrochemistry 10 mark
Q7. Explain how cathodic protection works using a suitable example? 3 mark
Q8. The following reactions (1) and (2) are part of a lead storage battery (Eº = 2.05 V).
(1) Pb(s) + SO42–(aq) → PbSO4(s) + 2e–
(2) PbO2(s) + 4H+(aq) + SO42–(aq) + 2e– → PbSO4(s) + 2H2O(l)
What is the change in Gibbs free energy of a cell in this battery upon discharging? Please provide the answer in kJ. 7 mark
Spectroscopy 10 mark
Q9. The structure of naproxen (a nonsteroidal anti-inflammatory drug) is shown below
Determine the index of hydrogen deficiency (IHD) of naproxen, C14 H14O3. 1 mark
Q10. A) Determine the number of signals you would expect to see in the 1 H-NMR spectrum of each of the following compounds. 1 mark
B) Determine the number of signals you would expect to see in the 13C-NMR spectrum of each of the compounds in part A, question 10. 1 mark
Q11. Match each of the following compounds with the appropriate spectrum. 1 mark
Q12. The following is a 'H-NMR spectrum for one of the following compounds:
i) Identify the compound responsible for this spectrum. 1 mark
ii) Assign all signals to their corresponding hydrogen atoms. Give brief reasoning(s) for your answer. 3 mark
Q13. The constitutional isomers 1-penten-3-ol and 2-pentanone have the molecular formula C5 H10O. The IR spectra of these isomers are shown below.
a) For the isomers, 1-penten-3-ol and 2-pentanone, list one major feature that appears in the IR spectrum of one compound but not the other compound. 1 mark
b) Assign each compound to its correct infrared spectrum. 1 mark
Reaction kinetics 10 mark
Q14. For the reaction:
2 HCrO4- + 3 HSO3- + 5 H+ → 2 Cr3+ + 3 SO42= + 5 H2O The rate law is:
rate of reaction = k [HCrO4-] [HSO3-]2 [H+]
Give the order with respect to HSO3- 1 mark
Q15. The following data were collected for the decomposition of acetaldehyde, CH3CHO (used in the manufacture of a variety of chemicals including perfumes, dyes and plastics), into methane and carbon monoxide. The data were collected at a temperature of 530°C.
CH3CHO → CH4 + CO
Determine the average rate of reaction between 60s and 80s. 5 mark
Q16. The formation of small amounts of nitric oxide, NO, in car engines is the first step in the formation 3of smog. Nitric oxide is readily oxidised to nitrogen dioxide by the reaction:
2 NO + O2 → 2 NO2.
Determine the rate law for the reaction. 4 mark
Condensed phases and real gases 10 mark
Q17. Sketch the approximate phase diagram for Br2 from the following information: normal melting point is 265.9 K, normal boiling point is 331.9 K, triple point is at p=5.87 x 103 Pa and T=265.7 K. Label the axes and the area where each phase is stable. 3 mark
Q18. A gas mixture contains N2 (X = 0.7422), O2 (X = 0.1992), Ar (X = 5.340 x 10–3), CO2 (X = 1.240 x 10–2), and He (X = 4.086 x 10–2). Calculate the partial pressure of Ar at an atmospheric pressure of 101.3 kPa. 5 mark