Kinetics and Equilibria

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Kinetics and Equilibria
2010-05-31 10:46:48

Chemistry AS
Show Answers:

  1. Particles in liquids and gases are always ____ and ____ with each other.
    • Moving
    • Colliding
  2. A reaction won't take place between two particles unless:
    They collide in the right direction. They need to be facing each other the right way

    They collide at least a certain minimum amount of kinetic energy
  3. What is this called?
    Collision Theory
  4. The minimum amount of kinetic energy particles need to react is called the _____ _____. The particles need this much energy to ___ the bonds to start the reaction.
    • Activation energy
    • Break
  5. Reaction with ___ activation energies happen pretty easily. But reaction with ___ activation energies don't. You need to give the particles extra ___ by _____ them.
    • Low
    • High
    • Energy
    • Heating
  6. What is this diagram called and state what happens at each number of the diagram
    1 - Here the bonds within each particle are being stretched

    2 - If the particles have enough energy, the bonds will break

    3 - This is the energy barrier that the particles have to overcome

    4 - The separate bits from each particle can't exist by themselves - so they form new bonds and release energy
  7. Molecules in a gas don't all have the ___ amount of energy.
  8. Name the diagram and what each letter represents.
    1 - The curve starts at (0,0) because no molecules have 0 energy

    2 - A few molecules are moving slowly

    3 - Most molecules are moving at moderate speed so their energies are at this range

    4 - Activation Energy

    5 - Some molecules have more than the activation energy. These are the only ones that can react
  9. Increasing the ______ or ______ makes reactions faster.
    • Temperature
    • Concentration
  10. If you increase the temperature, the molecules will on average have more _____ _____ and will move _____.
    • Kinetic energy
    • Faster
  11. So the greater proportion of molecules have energies greater than the ______ ______ and be able to _____. This changes the _____ of the Maxwell-Boltzmann distribution curve - pushing it to the ____.
    • Activation energy
    • React
    • Shape
    • Right
  12. And because molecules are moving faster, they'll ____ more often - another reason why ____ temperatures make a reaction faster... and why ___ temperature increases can lead to ____ increases in reaction rates.
    • Collide
    • Higher
    • Small
    • Large
  13. What other 3 things can affect the reaction rate?
    • Conc.
    • Surface area
    • Catalysts
  14. Increasing the conc. of reactants in a _____ or the pressure of a ___ means the particles are ____ together on average. If they are ____ together, they'll _____ more often. More ____ mean more chances to react.
    • Solution
    • Gas
    • Closer
    • Closer
    • Collide
    • Collisions
  15. If one reactant is in a big lump, then most the particles won't collide with other reactants. You need to crush these lumps so that more of the particles can come in ____ with the other reactants. A ____particle size means a ____ surface area. This leads to a _____ reaction.
    • Contact
    • Smaller
    • Larger
    • Speedier
  16. Catalysts are really useful. They _____ the activation energy by providing a ______ ____ for the bonds to be broken and remade. If the activation energy is ____, more particles will have enough _____ to react.
    • Lower
    • Different way
    • Lower
    • Energy
  17. Catalysts increases the ____ of a reaction by providing an ______ reaction pathway with a _____ activation energy. The catalyst is ______ unchanged at the end of the reaction.
    • Rate
    • Alternative
    • Lower
    • Chemically
  18. Catalysts are great. They don't get ____ up in reactions, so you only need a _____ ___ of catalyst. catalyse a ____ amount of stuff. they do take part in reactions, but they are ___ at the end.
    • Used
    • Tiny bit
    • Huge
    • Remade
  19. Homogeneous Catalysts work by forming _____
  20. A homogeneous catalyst is in the _____ state as the reactants. So if the reactants are gases, the catalyst must be a ___ too. And if the reactants are aqueous (dissolved in water), the catalyst has to be ____ as well.
    • Same
    • Gas
    • Aqueous
  21. A homogenous catalyst ____ up reactions by forming one or more _____ compounds with the reactants. The products are then formed from the _____ compounds.
    • Speeds
    • Intermediate
    • Intermediate
  22. The activation energy needed to form the intermediates (and to form the products from the intermediates) is ____ than that needed to make the products directly from the reactants.
  23. If a reaction is speeded up by a homogeneous catalyst, it's enthalpy profile will have ____ ____ on it.
    Two humps
  24. The catalyst is ____ again and caries of catalysing the reaction
  25. Another way to monitor the rate of reaction when a gas is produced is to stand the reactant vessel on a ____ - the mass will _____ as gas is evolved.
    • Balance
    • Decrease
  26. Not every reaction produces a gas, though. Some produce a _____ that clouds a solution. You can monitor this type of reaction....

    What is the problem with this?

    By measuring how quickly a marker becomes invisible through the cloudiness

    That with this method the result's subjective - different people might not agree over the exact point when the mark 'disappears'. And it only works if the reactants you started with were transparent.
  27. Reversible reactions can reach _____ equilibria.
  28. In a reversible reaction, as the reactions get used up, the forward reaction _____ _____ - and as more product is formed, the reverse reaction ____ ___.
    • Slows down
    • Speeds up
  29. After a while, the forward reaction will be going at exactly the ____ rate as the backward reaction. This is called dynamic equilibrium.
  30. A dynamic equilibrium can only happen in a ____ system. This means that...

    Nothing gets in or out.
  31. If you change the ____, ____ or _____ of a reversible reaction, you tend to alter the position of ______. This just means that you'll end up with different amounts of reactants and products at equilibrium.
    • Temperature
    • Conc.
    • Pressure
    • Equilibrium
  32. If the position of equilibria moves to the left, you get more _____. If it moves more to the right, you get more _____.
    • Reactants
    • Products
  33. Catalysts have _____ effect on the position of equilibrium. They can't increase ____ - but they do mean that equilibrium is reached ____.
    • No
    • Yield
    • Faster
  34. If you increase the concentration of a reactant, the equilibrium tires to get rid of the extra reactant. It does this by making _____ _____. So the equilibrium shifted to the ____.
    • More product
    • Right
  35. If you increase the conc. of the product, the equilibrium tries to remove the extra ____. This makes the reverse reaction go _____. So the equilibrium shifts to the ___.
    • Products
    • Faster
    • Left.
  36. Increasing the pressure shifts the equilibrium to the side with ___ gas molecules. This _____ the pressure.
    • Fewer
    • Reduces
  37. Decreasing the pressure shifts the equilibrium to the side with ____ gas molecules. This ___ the pressure.
    • More
    • Raises
  38. Increasing the temperature means adding ____.
    The equilibrium shifts in the ______ direction to absorb this heat.
    • Heat
    • Endothermic (Positive Delta H)
  39. Decreasing the temperature ____ heat.
    The equilibrium shifts in the ______ direction to try and replace the heat.

    Exothermic (Negative Delta H)
  40. If the forward reaction's endothermic, the reverse reaction will be ______, and vice versa.
  41. Predicting the effect of changing conditions is really important for _____ that use _____ ______. This is because they want to make as much _____ products as possible as cheaply as possible.
    • Industries
    • Reversible reactions
    • Useful