C12 Rate Of Reaction

Question 1

How do you calculate the rate of reaction at a certain point in a graph

Answer 1

Draw a tangent and calculate its gradient

Question 2

Equation for mean rate of reaction

Answer 2

Mean rate of reaction = Quantity of reactant used/product formed / time taken

Question 3

Equation for rate of reaction in gasses

Answer 3

Rate = volume of gas produced / time taken

Question 4

How do you measure the rate of reaction on a mass balance equation when one product is a gas

Answer 4

Rate = Change in mass / time taken

Question 5

Define activation energy

Answer 5

The energy level required for a successful collision (therefore reaction) to occur

Question 6

Name 2 things that will increase rate of reaction in a single directional reaction

Answer 6

• Increase frequency of collision (Concentration, Pressure, Density or surface area)
• Increasing the energy of the particles when they collide (increase in temperature)

Question 7

What will happen to reactants over the course of a reaction

Answer 7

• Overall system mass of both will decrease
• Reactant(s) not in excess will be fully used up
• Reactant(s) in excess will be used up but not completely

Question 8

Why does increasing temperature effect reaction rates (2 ways)

Answer 8

• Particles move faster, therefore more frequent collisions
• Particles have more energy so more collisions are successful in causing a reaction

Question 9

How does increasing the concentration of an acid increase its rate of reaction with an alkali metal?

Answer 9

• More reactant particles (of acid) in the reaction mixture, therefore collisions occur more frequently

Question 10

How does increasing the pressure in a single direction reaction effect the rate of reaction

Answer 10

• Less space between particles (more tightly packed) means there will be more frequent collisions
  (ONLY IN GASSES)

Question 11

Why would increasing the surface area of a reactant increase the rate of reaction

Answer 11

• Only reactant particles on the surface of a solid are able to collide and react with other reactants
• This means that the greater surface area, the more reactant particles are exposed and able to react with the other reactant at one time.
• This leads to more frequent collisions so a faster rate of reaction