Rates of reaction

• What is the term for how quickly a reaction happens?

  Rate of reaction
• How is the rate of reaction defined?

  Change in quantity divided by time
• What quantities can be measured to determine the rate of reaction?

  Mass or volume of gas
• What does the mean rate of reaction indicate?

  Average rate over the measurement period
• What is an example of an experiment to measure the rate of reaction?

  Reacting hydrochloric acid and sodium thiosulfate
• What does increased turbidity indicate in the hydrochloric acid and sodium thiosulfate experiment?

  The solution becomes cloudy
• When do you stop the timer in the turbidity experiment?

  When the cross is no longer visible
• How does temperature affect the time taken for a reaction?

  Higher temperature reduces reaction time
• How can the volume of gas produced be measured in a reaction?

  Using a gas syringe
• What does a graph of gas volume against time typically look like?

  Starts steeply then levels out
• How do you find the rate of reaction at a specific time on a graph?

  Draw a tangent at that point
• What is the formula to calculate the rate of reaction using a tangent?

  Change in quantity divided by time
• What factors can increase the rate of a reaction?

  Concentration, pressure, surface area
• Why does increasing concentration affect reaction rate?

  Particles collide more frequently
• How does increasing temperature affect reaction rate?

  Particles move more quickly and collide with energy
• What is the role of a catalyst in a reaction?

  Reduces activation energy needed
• What happens to a catalyst during a reaction?

  It is not used up
• What is a reversible reaction?

  Products can return to reactants
• What is the example given for a reversible reaction?

  The Haber process
• What occurs in a closed system at equilibrium?

  Rates of forward and reverse reactions equal
• What does Le Chatelier's principle state?

  System adjusts to counteract changes
• What happens if pressure is increased in a reaction with more moles on the left?

  Favors the forward reaction
• How does removing molecules from one side of a reaction affect equilibrium?

  Shifts equilibrium towards that side
• What does increasing temperature favor in an endothermic reaction?

  Favors the reverse reaction
• What does decreasing temperature favor in an exothermic reaction?

  Favors the forward reaction
• What is the relationship between forward and reverse reactions in reversible reactions?

  One is exothermic, the other is endothermic
• What is the main product of the Haber process?

  Ammonia
• What happens to the quantities of reactants and products at equilibrium?

  No overall change in quantities
• What occurs when a condition affecting equilibrium is changed?

  Rates of reactions adjust to new conditions