Chemistry WCH11 May 2020 Questions & Answers

Questions And Worked Solutions For Chemistry WCH11 May 2020

IAL Chemistry WCH11 May 2020 Questions - Complete Paper (pdf)

1. What is the empirical formula of butane?
2. When zinc is added to copper(II) sulfate solution, copper is formed.
3. How many molecules are there in 44.0g of carbon monoxide?
4. A compound has Mr = 84 and its composition by mass is 71.4% carbon, 9.6% hydrogen and 19.0% oxygen.
   What is the molecular formula of this compound?
5. The formula of barium chloride is BaCl₂.
   Which is correct for barium chloride?
6. The mass spectrum of a sample of an element is shown
7. What is the molecular formula of the compound shown?
8. A sequence of four molecules is shown.
9. Which ion does not have the electronic configuration shown?
10. What is the electronic configuration of the nitride ion, N^3– ?
11. Which of these ions has the smallest ionic radius?
12. What is the percentage atom economy, by mass, for the production of hydrogen in the reaction shown?
13. How many lone pairs of electrons are there in the outer shell of the sulfur atom in a molecule of H₂S?
14. Which equation represents the third ionisation energy for element J?
15. In which sequence are the molecules in order of decreasing bond angle?
16. Which pair of ions will form the compound with the most covalent character?
17. Which diagram best represents the electron density in a molecule of hydrogen chloride?

18. This question is about the structure of atoms.
    (a) State what is meant by the term orbital
    (b) State the shape of an s orbital and the shape of a p orbital
    (c) Describe what can be deduced about the electronic structure of sodium from its successive ionisation energies.
    (d) (i) The log of the fourth ionisation energy for six elements is shown in the table.
    Plot a graph of these data.
    (ii) Use your graph to estimate the fourth ionisation energy for sodium, in kJmol^–1
    (iii) Suggest why the fourth ionisation energies of neon and sodium are similar in magnitude even though the elements are in different periods of the Periodic Table.
19. This question is about the compound ammonium dichromate(VI), (NH₄)₂Cr₂O₇ .
20. This question is about polymers.
    (a) Plastic bags can be made from poly(lactic acid) (PLA), which is biodegradable.
    Lactic acid is obtained from corn.
    An equation for the polymerisation of lactic acid is shown.
    (i) Write a balanced equation for the polymerisation of propene using displayed formulae
    (ii) Give one difference between the polymerisation of propene and that of lactic acid.
    (iii) State the meaning of the term biodegradable.
    (iv) Give three advantages of biodegradable polymers
    (b) Isoprene is used to make synthetic rubber. The skeletal formula for isoprene is shown.
    (i) State why isoprene does not have geometric isomers
    (ii) A related molecule does show geometric isomerism.
    Draw the geometric isomer of this molecule
    (iii) Give a reason why a double bond may result in geometric isomerism.
    
21. This question is about the liquids cyclohexene, C₆H₁₀ , and bromine, Br₂.

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