Part B (i) Give the pH of water at the start of the experiment. It should be less than 7. Explain why distilled water has a pH in the acidic range. (ii) State the pH when CO2 was added to the water. Write out the balanced chemical equations that occurred when the carbon dioxide reacts with water. Explain why the pH drops upon adding CO2 to the water. (iii) State the pH when NaOH was then added to the reaction mixture. Write out the balanced chemical equation for the reaction that occurs when NaOH is added to the solution. Explain why the pH rises. Part C Note down your observations when dry ice was added over burning candles. 102 (i) Write out the formula for CO2 and assign oxidation states to the atoms. State the maximum oxidation state for a Group 14 element. Burning of a candle involves an exothermic reaction of the candle wax with oxygen. Explain why CO2 cannot react with oxygen. Explain why the CO2 extinguishes the flame. Part D (i) Using the following average bond dissociation energies determine the total dissociation energy of 1 mole of CO2 units if they were joined together by bridging oxygen atoms. (ii) Using the following average bond dissociation energies determine the total dissociation of 1 mole of individual CO2 molecules. Bond average bond enthalpy (kJ/mol) C-O 360 C=O 743 (iii) State which form of CO2 takes more energy to break down into its constituent atoms and therefore which is the thermodynamically more stable form. (iv) Relate the answer you gave in (iii) to the structural form and physical state that CO2 exhibits under normal conditions