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Thinking Task

Thinking Task. How do you know this a reversible reaction? Is this a physical or chemical change? How could you tell? What colour was the product and what colour was the reactant? Sure? Are all reactions reversible? Why/Why not? Can you explain the chemistry of this reaction?.

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Thinking Task

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  1. Thinking Task • How do you know this a reversible reaction? • Is this a physical or chemical change? How could you tell? • What colour was the product and what colour was the reactant? Sure? • Are all reactions reversible? Why/Why not? • Can you explain the chemistry of this reaction?

  2. Dynamic Equilibrium OXIDISED REDUCED Leucomethylene Blue Methylene Blue

  3. Our aim today… • Explain what happens at dynamicequilibrium to (i) the concentrations of reactants and products (ii) the rates of the forward and reverse reactions • Predict what happens to the position of equilibrium when we change (i) concentration (ii) pressure (iii) temperature

  4. NH3 + HCl NH4Cl Reactants Products

  5. time = 0 s Reactants Products

  6. time = 1 s Reactants Products

  7. time = 20 s Reactants Products

  8. time = 40 s Reactants Products

  9. time = 60 s Reactants Products

  10. Equilibrium No change in the concentration of reactants and products products reactants Concentration Time

  11. Dynamic equilibrium Reactants Products forward reverse

  12. Dynamic Reactants Products forward reverse

  13. Dynamic Reactants Products forward reverse

  14. Dynamic Equilibrium forward reaction rate = backward reaction rate forward reverse Rate of reaction Time

  15. Le Chatelier Any system at equilibrium will react to oppose the change

  16. 2NO2 (g) N2O4 (g) ΔH = -ve http://www.chem.arizona.edu/chemt/newconcept.swf

  17. C (s) + H2O(g) CO (g) + H2(g) Concentration Pressure

  18. ΔH = + 130 KJ mol -1 C (s) + H2O(g) CO (g) + H2(g)

  19. ΔH = + 130 KJ mol -1 HEAT + C (s) + H2O(g) CO (g) + H2(g)

  20. [Co(H2O)6] 2+(aq) + 4 Cl-(aq) [CoCl4]2-(aq) + 6H2O(l) ΔH = + 50 KJ mol -1 PINK BLUE

  21. Explain the effect on the position of equilibrium of.. CaCO3 (s) CaO (s) +CO2(g) 2 CrO42- (aq) +2H+(aq) Cr2O72-(aq)+H2O(l) Increasing the concentration of CaCO3 (2) Increasing the concentration of CaO (2) Decreasing the concentration of CaO (2) Decreasing the concentration of water (2) Adding OH -(aq) (3) Adding a catalyst (2) GRADE C/D GRADE B 2HI (g) I2(g)+H2(g) ΔH = +10.4 KJ mol-1 CO (g) +3H2(g) CH4(g)+H2O(g) ΔH = -ve Increasing the pressure (2) Increasing the temperature (2) Decreasing the pressure and decreasing the temperature (4) • Increasing the volume of the container (3) • Increasing the temperature (2) • If we increase the pressure, what effect will this have on: • Time taken to reach equilibrium(2) GRADE C/B GRADE A

  22. Make sure you include.. • What happens to the position of equilibrium? • Why?

  23. A dynamic equilibrium ? products reactants

  24. products reactants

  25. COCl2 (g) CO (g) + Cl2 (g) ΔH = +ve LEFT RIGHT FALSE TRUE

  26. Our aim today… • Explain what happens at dynamicequilibrium to (i) the concentrations of reactants and products (ii) the rates of the forward and reverse reactions • Predict what happens to the position of equilibrium when we change (i) concentration (ii) pressure (iii) temperature Areas I may need to go over or questions I still have:

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