Chemistry C6

• When are reactions usually fasted?

  at the beginning
• what is the equation to find the mean rate of a reaction?

  Quantity of react used OR product formed/ time
• What does the gradient of the line represent?

  rate of reaction, steeper the line , faster the rate
• What must happen for a chemical reaction to take place?

  Particles collide with enough energy to react (a successful collision)
• What is the activation energy?

  the minimum energy particles need to react
• The rate of reaction depends on the ________of successful collisions?

  Frequency
• Why do reactions slow overtime?

  less reactant particles, (so successful collisions between reactant particles less frequent)
• Why does an increased concentration increase th rate?

  particles closer together so successful collisions more frequent

  (Rate proportional to concentration)
• Why does increasing pressure increase rate?

  particles closer together so successful collisions more frequent

  (rate proportional to pressure)
• Why does an increased surface area of solids increase the rate?

  more reactant particles on surface (so successful collisions more frequent)

  **rate is proportional to surface area
• Why does increasing temperature increase rate of reaction?

  particles have more energy and so more of the collisions are succesful

  particles move faster and so collisions more frequent

  **rate and temperature are not proportional- doubling temp more than doubles rate as increasing temp increases both success and frequency of collisions
• What is a catalyst?

  substance that speeds up a reaction with being used up itself
• Do catalysts appear in the overall chemical equation?

  No.
• How do catalysts work?

  provide a different reaction pathway that has a lower activation energy
• How is rate found in turbidity practical?

  1000/ time
• What does it mean if a reaction is reversible?

  once products have been made they can turn back into the reactants
• What is a closed system?

  no chemicals can get in or out
• What is happening at equilibrium?

  the forwards and reverse/backwards reactions are taking place simultaneously, at the same rate
• What is Le chatelier’s principle?

  equilibrium strikes back
• What does it mean if the equilibrium lies to the left?

  there are more of the reactants than products present at equilibrium

  REVERSE FOR RIGHT
• What happens in the pressure, temperature and concentration are increased to the equilibrium?

  • temp- move indirection of endothermic reaction to reduce temp
  • pressure- moves to side with fewest gas molecules to reduce pressure
  • concentration- moves to reduce it by doing more of the reaction that uses it up
• What happens to the position of equilibrium is temperature, pressure and concentration are drecreased?

  • temperature- moves in direction of exothermic reaction to increase temp
  • pressure- moves towards side with more gas molecules to increase pressure
  • concentration- moves to increase it by doing more of the reaction that makes it