Rates of Reaction

• What is the Haber process an example of?

  Le Chatelier's principle
• In which state is the reaction of the Haber process carried out?

  Gaseous state
• What happens to the equilibrium when the temperature is increased?

  It shifts to the left, increasing the amount of reactants
• What is the effect of decreasing the temperature on the equilibrium?

  It shifts to the right, increasing the amount of product
• What occurs when the concentration of reactants is increased?

  The equilibrium shifts to the right to produce more product
• What happens when the concentration of products is increased?

  The equilibrium shifts to the left to reach equilibrium again
• What is the effect of increasing the pressure in a gas reaction?

  The equilibrium shifts to the right, where there are fewer molecules of gas
• What occurs when the pressure in a gas reaction is decreased?

  The equilibrium shifts to the left, where there are more gas molecules
• What does Le Chatelier's principle state?

  If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change
• What is dynamic equilibrium?

  An equilibrium where the forward and backward reactions are happening at the same rate
• What is activation energy?

  The minimum energy required for a chemical reaction to take place
• What does collision theory state?

  For a chemical reaction to happen, particles must collide with sufficient energy
• What two factors affect the rate of a reaction according to collision theory?

  The frequency of collisions and the energy with which particles collide
• How does increasing the concentration of a solution affect the rate of reaction?

  It increases the frequency of collisions, making the reaction faster
• What is the relationship between concentration and rate of reaction?

  Concentration is directly proportional to the rate of reaction
• What does a steeper gradient on a rate of reaction graph indicate?

  A faster reaction
• What happens to the graph of a reaction as the same amount of reactant is used?

  The graph flattens off (plateaus)
• What factors can change the rate of a chemical reaction?

  • Changing temperature
  • Changing pressure
  • Changing the concentration of a solution
  • Changing the surface area
  • Adding a catalyst

  
• What is a biological catalyst called?

  Enzyme
• What is a reaction profile?


  A graph showing the energies of the reactants and products at different stages of the chemical reaction
• How does increasing the surface area of a solid affect the rate of reaction?

  It increases the frequency of collisions, thus increasing the rate of reaction
• What is the role of a catalyst in a chemical reaction?


  It speeds up a reaction by lowering the activation energy
• Why are catalysts not included in chemical equations?

  Because they are not used up in a chemical reaction
• How does increasing gas pressure affect the rate of reaction?

  It increases the rate of reaction by increasing the frequency of collisions
• What is the optimum temperature for most enzymes?

  Around 37°C
• How does increasing temperature affect particle movement and reaction rate?

  Particles move faster, increasing collision frequency and energy
• How can the rate of reaction be calculated?

  By measuring the quantity of reactant used or product made in a certain time
• What units can be used to measure the quantity in rate of reaction calculations?

  Volume in cm³ or mass in grams (g)
• What is the formula for calculating the rate of reaction using reactant used?

  Rate of Reaction = $\frac{Reactant \, used}{time}$
• What is the formula for calculating the rate of reaction using product made?

  Rate of Reaction = $\frac{Product \, made}{time}$
• How do you find the rate of reaction from a graph?

  The gradient of a volume or mass/time graph gives the rate of reaction
• What should you do to measure the gradient of a curve on a graph?

  Draw a tangent to the curve
• What is the first step to draw a tangent on a graph?

  Line your ruler up across your graph, touching the line at the point of interest
• How do you calculate the mean rate of reaction from a graph?

  Pick two y values and two x values, subtract the largest from the smallest, and divide the y value by the x value
• What are the methods to measure the rate of a chemical reaction?

  1. Measuring the mass lost in a chemical reaction
  2. Measuring the volume of gas produced
  3. Time taken to make an X disappear

  
• What is the definition of rate of reaction?


  The rate at which reactants are being turned into products
• What is a reactant?


  What is used in a chemical reaction
• What is a product?

  What is made in a chemical reaction
• What is a catalyst?

  A substance which speeds up a chemical reaction without being used up
• What is a tangent in the context of a graph?

  A straight line that touches a curve at a point