C6: RATE OF REACTION

Question 1

What is the formula for rate of reaction?

Answer 1

rate of reaction (g/s or cm^3/s) = amount of reactant used (g or cm^3) / time (s)

or

rate of reaction (g/s or cm^3/s) = amount of product formed (g or cm^3) / time (s)

Question 2

Collision theory

Answer 2

-in order for a reaction to happen particles must collide with sufficient energy
-the minimum amount of energy is called the activation energy
-if the frequency of collisions is increased the rate of reaction will increaee

Question 3

How does increasing conc affect rate of reaction?

Answer 3

-more particles in a certain volume
-more frequent collisions
-rate increases

Question 4

How does increasing temp affect rate of reaction?

Answer 4

-particles have more kinetic energy
-more frequent collisions
-more successful collisions

Question 5

How does increasing surface area (s) affect rate of reaction?

Answer 5

-more of the surface is exposed to react
-more frequent collisions

Question 6

How does adding a catalyst affect rate of reaction?

Answer 6

-lowers activation energy
-increases rate of reaction by providing an alternate pathway for the reaction that has a lower activation energy

Question 7

RP- Investigate rate of reaction with different concs (by measuring volume of gas produced) : method

Answer 7

-measure 50cm^3 of 1.0 mol/dm^3 of HCl with a measuring cylinder
-pour acid into conical flask
-connect tube and bung to gas syringe
-add a 3cm strip of magnesium ribbon to the conical flask, put the bung back into the flask as quickly as possible and start the timer
-record volume of gas produced every 10s
-repeat with 1.5 mol/dm^3 conc of HCL

Question 8

RP- Investigate rate of reaction with different temps (by measuring colour change) : method

Answer 8

-measure 50cm^3 of sodium thiosulfate solution into a conical flask using a measuring cylinder
-place conical flask on top of a printed black cross
-measure 20cm^3 of HCl into a test tube and heat to 40°C using a water bath
-add the sodium thiosulfate into the conical flask and start the timer
-time how long it takes for the cross to disappear
-repeat for other temps of HCl (30°C, 20°C, 10°C)
=> calculate ROR for each and put on graph

Question 9

RP- Investigate rate of reaction

What are some Safety Precautions?

Answer 9

• Wear safety glasses.
• Take care when using glassware.