CAPE Chemistry Unit 1 · 2016 · Paper 2

36 questions and parts from this paper. Open one to see it in full, then practise it on Quelpr and get it marked against the mark scheme.

1. 1(a)(i)2 marksState THREE postulates of Dalton's atomic theory.
2. 1(a)(ii)2 marksLater developments in science led to the modification of the atomic theory. Explain the modification of ONE of the postulates.
3. 1(b)(i)1 markIdentify the ion responsible for the green colour.
4. 1(b)(ii)4 marksGiven that the sulfate(IV) ion, SO₃²⁻, is converted to the sulfate(VI) ion, SO₄²⁻, in the presence of water, deduce the balanced equation for the redox reaction between Cr₂O₇²⁻(aq) and SO₃²⁻.
5. 1(b)(iii)1 markIdentify the oxidizing agent in (b) (ii).
6. 1(c)5 marksComplete the table by inserting the missing observations or inferences.
7. 2(a)(i)1 markDefine EACH of the following terms: Weak acid
8. 2(a)(ii)2 marksDefine EACH of the following terms: Kₐ
9. 2(b)(i)2 marksWrite an equation to represent the dissociation of carbonic acid in aqueous solution.
10. 2(b)(ii)1 markWrite the Kₐ expression for the reaction in (b) (i).
11. 2(b)(iii)4 marksCalculate the pH of a 0.100 mol dm⁻³ aqueous solution of carbonic acid. (Kₐ = 4.5 × 10⁻⁷ mol dm⁻³ at 25 °C.)
12. 2(c)5 marksA student was given a particular brand of club soda (carbonated beverage) to determine the carbonic acid content. Outline the experimental steps required for the investigation if the student is given 200 cm³ of 0.100…
13. 3(a)(i)2 marksExplain, in terms of structure and bonding, why aluminium has a higher melting point than sodium
14. 3(a)(ii)2 marksExplain, in terms of structure and bonding, why silicon has the highest melting point in the period
15. 3(a)(iii)3 marksExplain, in terms of structure and bonding, why sulfur melts at a higher temperature than phosphorous.
16. 3(b)(i)2 marksComplete Table 2 by describing the reaction of EACH oxide with water and suggesting a pH value for the resulting liquid.
17. 3(b)(ii)2 marksWrite the equation which represents the reaction of water with P₄O₁₀.
18. 3(c)(i)2 marksWrite equations to show what happens when EACH of the following chlorides reacts with water: SiCl₄
19. 3(c)(ii)2 marksWrite equations to show what happens when EACH of the following chlorides reacts with water: AlCl₃
20. 4(a)(i)4 marksDescribe how the bonds are formed in EACH of the solids, potassium chloride and iodine.
21. 4(a)(ii)2 marksComplete Table 3 by comparing the physical properties of potassium chloride (KCl) and iodine (I₂).
22. 4(b)(i)3 marksAccount for EACH of the following statements: The boiling point of H₂O is higher than that of H₂S.
23. 4(b)(ii)3 marksAccount for EACH of the following statements: The molecules of aluminium fluoride in the presence of ammonia forms a white solid of formula NH₄AlF₄. (Include an appropriate equation in your account.)
24. 4(c)3 marksExplain the difference between the shapes of NH₃ and NH₄⁺.
25. 5(a)(i)4 marksState FOUR characteristics of a reaction in 'dynamic equilibrium'.
26. 5(a)(ii)2 marksWrite the expression for the equilibrium constant in terms of partial pressures, Kₚ, for the reaction shown by the equation above.
27. 5(a)(iii)2 marksState TWO factors which would NOT affect the equilibrium of the reaction shown by the equation above.
28. 5(b)(i)2 marksDescribe the effect of decreasing the temperature on the equilibrium of the reaction
29. 5(b)(ii)2 marksDescribe the effect of decreasing the temperature on the value of Kₚ.
30. 5(c)3 marksWhen 0.5 mol of hydrogen and 0.5 mol of iodine are allowed to reach equilibrium in a 1.00 dm³ flask at 500 °C and 1.01 × 10⁵ N m⁻², the amount of hydrogen iodide at equilibrium is 0.78 mol. Calculate Kₚ at 500 °C if the…
31. 6(a)4 marksList FOUR properties of transition metals.
32. 6(b)(i)1 markWrite the electronic configuration using the s, p and d orbitals of the titanium ion.
33. 6(b)(ii)4 marksExplain the colour of the aqueous solution.
34. 6(c)(i)1 markDescribe what would be observed when concentrated hydrochloric acid is slowly added to an aqueous solution of Co²⁺.
35. 6(c)(ii)2 marksWrite an ionic equation to represent the observation in (c) (i).
36. 6(c)(iii)3 marksUsing the concept of stability constant, explain the changes observed in (c) (ii).