Rates of Reaction

Question 1

Which equations can be used to measure rate of reaction?

Answer 1

• Reactant used/Time
• Product formed/Time

Rate of reaction can be measured in g/s

Question 2

What are the factors that affect rate of reaction?

Answer 2

• Surface area of solid
• Concentration of solution
• Temperature
• Presence of catalyst
• Pressure of a gas

Question 3

How do you measure the effect of surface area on rate of reaction?

Answer 3

• Put chips of calcium carbonate in a solution of hydrochloric acid within a conical flask
• Measure the gas produced by measuring the displacement of water in a connected, sealed meauring cylinder
• Repeat for different surface areas to see the change in rate of gas produced

Question 4

How do you measure the effect of concentration on rate of reaction?

Answer 4

• Add acid to a solution of sodium thiosulfate above a sheet of paper with a cross
• Measure the amount of time it takes for the cross to become invisible due to the solution becoming opaque
• Repeat with different concentrations of sodium thiosulphate to see the change in time taken for the cross to disaappear

Question 5

How do you measure the effect of temperature on rates of reaction?

Answer 5

• Heat a conical flask of hydrochloric acid to a specific temperature using a water bath
• Add a strip of magnesium, and measure the time it takes for it to fully dissolve
• Repeat with different temperatures to see the change in time taken for the magnesium to dissolve

Question 6

How do you measure the effect of a catalyst on rates of reaction?

Answer 6

Do the experiment for measuring rate of reaction on surface area but add a chosen catalyst and repeat without the catalyst

Question 7

What effect does temperature have on rate of reaction and why?

(Using collision theory)

Answer 7

• As temperature increases, the rate of reaction increases
• This is because particles will have more kinetic energy which increases their speed, so increases the number of successful collisions per second
• The increase in kinetic energy also increases the frequency of collisions happening where the particles have sufficient activation energy

Question 8

What effect does surface area of a solid have on rate of reaction and why?

(Using collision theory)

Answer 8

• As surface area of solid increases, the rate of reaction increases
• This is because the particles will be more exposed to other reactant particles, so more successful collisions will happen per second

Question 9

What effect does concentration of a solution/ pressure of gas have on rate of reaction and why?

(Using collision theory)

Answer 9

• As concentration of a solution/pressure of gas increases, the rate of reaction increases
• This is because a higher concentration will mean more particles in a given volume, which means there will be more successful collisions per second between particles

Question 10

What effect does the presence of a catalyst have on rate of reaction and why?

Answer 10

• If a catalyst is present, the rate of reaction is increased
• This is because the catalyst lowers the activation energy of a reaction by providing an alternate reaction pathway which requires less energy, so more collisions where both particles have sufficient activation energy occur

• A catalyst does not get used up or changed
• Activation energy is the initial energy required to break the bonds of the reactants