Some oxides of elements in Period 3 are shown. Na₂O Al₂O₃ P₄O₆ P₄O₁₀ SO₂ SO₃

1. (a)(i)Define reducing agent.[1]
2. (a)(ii)Write an equation for the reaction of Na₂O with water.[1]
3. (b)(i)State what is meant by amphoteric.[1]
4. (b)(ii)Al₂O₃ is purified from bauxite in several steps. The first step involves heating Al₂O₃ with an excess of NaOH(aq). A colourless solution forms. Write an equation for this reaction.[1]
5. (b)(iii)Al₂O₃ is used as a catalyst in the dehydration of alcohols. State the effect of using Al₂O₃ as a catalyst in the dehydration of alcohols. Use the Boltzmann distribution in [Figure 2.1] to help explain your answer.[3]
6. (c)(i)P₄O₆ is a white solid that has a melting point of 24°C. Solid P₄O₆ reacts with water to form H₃PO₃. Deduce the type of structure and bonding shown by P₄O₆. Explain your answer.[2]
7. (c)(ii)Determine the oxidation number of P in H₃PO₃.[1]
8. (c)(iii)When P₄O₆(s) is heated with oxygen it forms P₄O₁₀(s). P₄O₆(s) + 2O₂(g) → P₄O₁₀(s) ∆H₁ = –1372 kJ mol⁻¹ The enthalpy change of formation, ∆H_f, of P₄O₁₀(s) is –3012 kJ mol⁻¹. Calculate the enthalpy change of formation, ∆H_f, of P₄O₆(s). ∆H_f of P₄O₆(s) =[1]
9. (c)(iv)Write an equation for the reaction of P₄O₁₀ with water.[1]
10. (d)(i)SO₂ and SO₃ are found in the atmosphere. The oxidation of SO₂ to SO₃ in the atmosphere is catalysed by NO₂. The first step of the catalytic oxidation is shown in equation 1. equation 1 SO₂(g) + NO₂(g) ⇌ SO₃(g) + NO(g) Construct an equation to show how NO₂ is regenerated in the catalytic oxidation of SO₂.[1]
11. (d)(ii)NO₂ can also react with unburned hydrocarbons to form photochemical smog. State the product of this reaction that contributes to photochemical smog.[1]
12. (d)(iii)[Figure 2.2] shows how the temperature of the atmosphere varies with height from the ground. The equilibrium reaction in equation 1 has ∆H = –168 kJ mol⁻¹. Suggest how the position of this equilibrium differs at a height of 20 km compared with a height of 50 km from the ground. Explain your answer.[2]

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