If 60 cm³ of a saturated solution of KNO, contains 15.6 g of the salt at 25 °C, calculate the solubility of KNO3 in mol dm-3 at that temperature. [K=39.0, 0=16.0, N=14.0]

Here are the solutions to the questions: b) (ii) To calculate the solubility of KNO_3 in mol dm^-3: Step 1: Calculate the molar mass of KNO_3. Molar mass of KNO_3 = K + N + (3 × O) = 39.0 + 14.0 + (3 × 16.0) = 39.0 + 14.0 + 48.0 = 101.0 g/mol Step 2: Convert the mass of KNO_3 to moles. Moles of KNO_3 = MassMolar mass = 15.6 g101.0 g/mol = 0.154455 mol Step 3: Convert the volume of the solution from cm^3 to dm^3. Volume in dm^3 = 60 cm^31000 cm^3/dm^3 = 0.060 dm^3 Step 4: Calculate the solubility in mol dm^-3. Solubility = Moles of soluteVolume of solution in dm^3 = 0.154455 mol0.060 dm^3 = 2.57 mol dm^-3 The solubility of KNO_3 is 2.57 mol dm^-3. c) (i) To prepare PbCl_2 from Pb(NO_3)_2 and a mineral acid: Dissolve lead(II) nitrate (Pb(NO_3)_2) in water to form an aqueous solution. Add a mineral acid containing chloride ions, such as dilute hydrochloric acid (HCl), to the lead(II) nitrate solution. Lead(II) chloride (PbCl_2) will precipitate out as a white solid. Filter the mixture to separate the solid PbCl_2, then wash the precipitate with distilled water and dry it. (ii) The equation for the reaction is: Pb(NO_3)_2 (aq) + 2HCl (aq) → PbCl_2 (s) + 2HNO_3 (aq) d) (i) The electron configuration of copper is 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^1 and not 1s^2 2s^2 2p^6 3s^2 3p^6 3d^9 4s^2 because a completely filled d-subshell (3d^10) is more stable than a partially filled d-subshell (3d^9). An electron from the 4s orbital is promoted to the 3d orbital to achieve this greater stability. (ii) The two oxidation states of iron in its chlorides are +2 and +3. These correspond to iron(II) chloride (FeCl_2) and iron(III) chloride (FeCl_3). (iii) One chemical process in which iron is used as a catalyst is the Haber process. That's 2 down. 3 left today — send the next one.