The reaction scheme shows some reactions of calcium. [Figure: Reaction scheme showing Ca(s) to Ca(NO₃)₂(aq) via HNO₃ (reaction 1), then to Ca(OH)₂(aq) via NaOH(aq). From Ca(OH)₂(aq) to CaO(s) via heat (reaction 2, CO₂(g) byproduct), then from CaO(s) to CaCO₃(s) + H₂O(l) (reaction 3, excess CO₂(g) involved). From CaCO₃(s) + H₂O(l) to Ca(HCO₃)₂(aq) via excess CO₂(g). Also from CaO(s) to CaC₂(s) via C(s) (reaction 4).]

1. (a)(i)Reaction 1 produces Ca(NO₃)₂ and one other product. Identify the other product.[1]
2. (a)(ii)Construct an equation for the thermal decomposition of Ca(NO₃)₂(s).[1]
3. (a)(iii)State the trend in the thermal stability of the Group 2 nitrates down the group.[1]
4. (a)(iv)In reaction 3, excess CO₂ is bubbled through water containing CaCO₃. A solution of Ca(HCO₃)₂(aq) forms. Construct an equation for reaction 3.[1]
5. (b)Describe how Ca(OH)₂ is used in agriculture.[1]
6. (c)(i)In reaction 4, calcium carbide, CaC₂, is formed from CaO. CaC₂ contains the C₂²⁻ anion. Each carbon in C₂²⁻ is sp hybridised. Describe how sp hybridised orbitals are formed.[1]
7. (c)(ii)Sketch a diagram to show how two sp hybrid orbitals can form a sigma (σ) bond.[2]
8. (d)(i)The flowchart shows some reactions of CaC₂. CaC₂ N₂ → CaCN₂ CaCN₂ + H₂O (reaction 5) → CaCO₃ + NH₃ CaC₂ NaCl and C → NaCN Reaction 5 can be used to prepare NH₃. CaCN₂ + 3H₂O → CaCO₃ + 2NH₃ Calculate the minimum mass, in tonnes, of calcium cyanamide, CaCN₂, that is required to produce 1.50 × 10⁶ tonnes of NH₃. Show your working. 1 tonne = 1.00 × 10⁶ g minimum mass of CaCN₂ = ...................................... tonnes[2]
9. (d)(ii)Draw the structure of the organic products formed in the following reactions. CH₃CH₂Br NaCN dissolved in ethanol → [Box 1] CH₃CH₂Br H₂SO₄(aq) heat under reflux → [Box 2] [Propane-2-one structure] NaCN and HCN → [Box 3][3]

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