2- rates of reaction

• Why is it important for manufacturers to know the rate of a chemical reaction?

  To maximize product in the shortest time
• What is the definition of the rate of reaction?

  Change in concentration per unit time
• What is the equation for calculating the rate of reaction?

  Rate = change in concentration/time
• What happens to the rate of reaction at the beginning?

  It is fastest due to high reactant concentration
• Why does the rate of reaction slow down as it proceeds?

  Concentration of reactants decreases over time
• When does the rate of reaction become zero?

  When one reactant has been used up
• How are rates of reaction measured?

  By measuring concentration over time
• What is used to find the initial rate of reaction from a graph?

  The initial slope or gradient of the line
• How do you calculate the rate from a graph at point B?

  Rate = change in concentration/time
• What does doubling the concentration of propanone do to the initial rate?

  It doubles the initial rate of reaction
• What happens when the concentration of iodine is doubled?

  It has no effect on the initial rate
• What are the factors that can affect the rate of a reaction?

  • Surface area of a solid
  • Concentration of a solution
  • Temperature of the reaction
  • A catalyst
  • Pressure of gaseous reactions
  • Light
• What is required for a chemical reaction to occur according to collision theory?

  Molecules must collide with correct force and direction
• What is the minimum energy required for a reaction called?

  Activation energy
• What happens in an exothermic reaction regarding energy?

  Reactants lose energy and heat is released
• What does a negative ΔH indicate in an exothermic reaction?

  Products have less energy than reactants
• What happens to the rate of reaction if concentration increases?

  The rate of reaction increases
• How does increasing pressure affect gaseous reactions?

  It increases the concentration of gas molecules
• Why do smaller particles react more quickly than larger ones?

  They have a greater surface area for collisions
• How does temperature affect the rate of reaction?

  Higher temperature increases molecular kinetic energy
• What does the Boltzmann energy distribution curve illustrate?

  More molecules have energy greater than activation energy at higher temperatures
• What is a catalyst?

  A substance that increases reaction rate without being used
• How does a catalyst affect activation energy?

  It provides an alternative route of lower activation energy
• What are the two types of catalysts?

  • Homogeneous
  • Heterogeneous
• What is a homogeneous catalyst?

  A catalyst in the same phase as reactants
• What is a heterogeneous catalyst?

  A catalyst in a different phase from reactants
• Why are heterogeneous catalysts commonly used in industry?

  They are easy to separate from products
• What role does palladium play in catalytic converters?

  It catalyzes the oxidation of carbon monoxide
• How do catalysts affect the equilibrium of a reaction?

  They do not affect the position of equilibrium
• What type of metals are commonly used as industrial catalysts?

  Transition metals
• How do gases interact with metal catalysts during a reaction?

  Gases are adsorbed onto the metal surface
• What happens to the products after a reaction on a catalyst surface?

  They are desorbed from the surface
• What reaction does palladium catalyze in a catalytic converter?

  Oxidation of carbon monoxide to carbon dioxide
• What is the role of iron in the Haber process?

  Production of ammonia
• What is vanadium(V) oxide used for in industry?

  Manufacture of sulfuric acid
• What is nickel used for in the food industry?

  Hydrogenation of unsaturated oils
• Why are heterogeneous catalysts preferred in industrial reactions?

  They are easy to separate from products
• How do catalysts affect the activation energy of a reaction?

  They lower the activation energy
• What environmental benefit comes from using catalysts in reactions?

  Less fossil fuels are burned
• What are enzymes in the context of industrial processes?

  Biological catalysts