3.9: Describe Experiments to Investigate the Effects of Changes in Surface Area of a Solid, Concentration of a Solution, Temperature and the Use of a Catalyst on the Rate of a Reaction

EFFECT OF SURFACE AREA OF A SOLID ON THE RATE OF REACTION:

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EFFECT OF SURFACE AREA ON THE RATE OF REACTION

Diagram showing the Process of Downwards Displacement to Investigate the Effect of Surface Area on the Rate of Reaction

METHOD: Add dilute Hydrochloric acid into a conical flask Use capillary tube to connect flask to a measuring cylinder placed upside down in a bucket of water (downwards displacement) Add Calcium Carbonate chips into conical flask and close the bung Measure the volume of gas produced in measuring cylinder in a fixed period of time Repeat with different sizes of Calcium Carbonate chips (solid, crushed and powder)

RESULT: As the surface area of solid increases, the rate of reaction will increase (positive correlation) This is because as the surface area to volume ratio of a solid increases, more surface area particles are exposed to the other reactant This allows more frequent successful collisions to occur, increasing the rate of reaction

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EFFECT OF CONCENTRATION OF A SOLUTION ON THE RATE OF REACTION:

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EFFECT OF CONCENTRATION ON THE RATE OF REACTION

Diagram Showing the Apparatus Needed to Investigating the Effect of Concentration on the Rate of Reaction

METHOD: Measure 50 cm3 of Sodium Thiosulfate Solution in a Flask Measure 5 cm3 of Dilute Hydrochloric Acid into a Measuring Cylinder Draw a Cross on a Piece of Paper and Put it Underneath the Flask Add the Acid into the Flask and Immediately Start the Stopwatch Look Down at the Cross from Above and Stop the Stopwatch when the Cross can No Longer be Seen Repeat Using Different Concentrations of Sodium Thiosulfate Solution (Mix Different Volumes of Sodium Thiosulfate Solution with Water to Dilute it)

RESULT: Increase in the Concentration of a Solution, the Rate of Reaction will Increase This is because there will be More Reactant Particles in a Given Volume, Allowing More Frequent and Successful Collisions, Increasing the Rate of Reaction

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EFFECT OF TEMPERATURE ON THE RATE OF REACTION:

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EFFECT OF TEMPERATURE ON THE RATE OF REACTION

Diagram Showing the Apparatus Needed to Investigate the Effect of Temperature on the Rate of Reaction

METHOD: Dilute Hydrochloric Acid is Heated to Set Temperature Using a Water Bath Add the Dilute Hydrochloric Acid into a Conical Flask Add a Strip of Magnesium and Start the Stopwatch Stop the Time when the Magnesium Fully Dissolves Repeat at Different Temperatures and Compare Results

RESULT: Increase in the Temperature, the Rate of Reaction will Increase This is because the Particles will have More Kinetic Energy than the Required Activation Energy, therefore More Frequent and Successful Collisions will Occur, Increasing the Rate of Reaction

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EFFECT OF A CATALYST ON THE RATE OF REACTION:

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EFFECT OF CATALYST ON THE RATE OF REACTION

Diagram Showing the Apparatus Needed to Investigate the Effect of a Catalyst on the Rate of Reaction

METHOD: Add Hydrogen Peroxide into a  Conical Flask Use a Capillary Tube to Connect this Flask to a Measuring Cylinder Upside Down in a Bucket of Water (Downwards Displacement) Add the Catalyst Manganese (IV) Oxide into the Conical Flask and Close the Bung Measure the Volume of Gas Produced in a Fixed Time using the Measuring Cylinder Repeat Experiment Without the Catalyst of Manganese (IV) Oxide and Compare Results

RESULT: Using a Catalyst will Increase the Rate of Reaction The Catalyst will Provide an Alternative Pathway Requiring Lower Activation Energy so More Colliding Particles will have the Necessary Activation Energy to React This will Allow More Frequent and Successful Collisions, Increasing the Rate of Reaction

3.10: Describe Effects of Changes in Surface Area of a Solid, Concentration of a Solution, Pressure of a Gas, Temperature and the Use of a Catalyst on the Rate of a Reaction

EFFECT OF FACTORS ON THE RATE OF REACTION

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*SURFACE AREA OF SOLID:

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SURFACE AREA OF SOLID

Graph showing the Effect of Surface Area on the Rate of Reaction

EXPLANATION: Compared to the reaction using lumps of reactant, the graph for the reaction using powdered reactant has a steeper gradient at the start, and plateaus faster This shows that as the surface area of a solid increases, the rate of reaction will increase (positive correlation)

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s*CONCENTRATION OF A SOLUTION:
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CONCENTRATION OF A SOLUTION

Graph showing the Effect of Concentration on Rate of Reaction

EXPLANATION: Compared to the reaction with low concentration of reactant, the graph with high concentration of reactant has a steeper gradient at the start, and plateaus faster This shows that as the concentration of a solution increases, the rate of reaction will increase (positive correlation)

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s*PRESSURE OF A GAS:
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PRESSURE OF A GAS

Graph showing the Effect of Pressure on the Rate of Reaction

EXPLANATION: Compared to the reaction using gas at low pressure, the graph of reaction using gas at high pressure has a steeper gradient at the start, and plateaus faster This shows that as the pressure of gas increases, the rate of reaction will increase

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s*TEMPERATURE:
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TEMPERATURE

Graph showing Effect of Temperature on Rate of Reaction

EXPLANATION: Compared to the reaction at low temperature, the graph for reaction at high temperature has a steeper gradient, and plateaus faster This shows that as temperature increases, the rate of reaction will increase

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s*USE OF A CATALYST:
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CATALYST

Graph showing Effect of Catalyst on Rate of Reaction

EXPLANATION: The diagram shows that when a catalyst is used, the activation energy - certain amount of energy needed for reaction to proceed, is reduced as it creates an alternative pathway requiring lower activation energy (shown by dotted graph with lower maximum energy level), Allowing More Successful and Frequent Collisions This allows more frequent successful collisions to occur, increasing the rate of reaction This shows that when a catalyst is used, the rate of reaction increases

3.11: Explain the Effects of Changes in Surface Area of a Solid, Concentration of a Solution, Pressure of a Gas and Temperature on the Rate of a Reaction in Terms of Particle Collision Theory

PARTICLE COLLISION THEORY: For reaction to occur, reactant particles need to collide with one another

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EFFECT OF FACTORS ON THE RATE OF REACTION:

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*SURFACE AREA OF SOLID:

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SURFACE AREA OF SOLID

Diagram showing the Effect of Surface Area on Rate of Reaction

EXPLANATION: As the surface area of solid Increases, the rate of reaction increases This is because as the surface area of solid increases, more surface area particles will be exposed to the other reactant This causes more frequent successful collisions to occur, increasing the rate of reaction

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s*CONCENTRATION OF A SOLUTION:
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CONCENTRATION OF A SOLUTION

Diagram showing Effect of Concentration on Rate of Reaction

EXPLANATION: As the concentration of solution increases, the rate of reaction increases This is because as the concentration of solution increases, there will be more Reactant Particles in a given volume This allows more frequent successful collisions to occur, increasing the rate of reaction

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s*PRESSURE OF A GAS:
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PRESSURE OF A GAS

Diagram Showing Effect of Pressure on Rate of Reaction

EXPLANATION: As the pressure of gas increases, the rate of reaction increases This is because as the pressure of gas increases, there will be more reactant gas particles in a given volume This allows more frequent successful collisions to occur, increasing the rate of reaction

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*TEMPERATURE:

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TEMPERATURE

Diagram Showing Effect of Temperature on Rate of Reaction

EXPLANATION: As the temperature increases, the react of reaction increases This is because as temperature increases, particles will gain kinetic energy, vibrating and moving faster This allows more frequent successful collisions to occur, increasing the rate of reaction

3.12: Know that a Catalyst is a Substance that Increases the Rate of a Reaction, but is Chemically Unchanged at the End of the Reaction

CATALYST: Substance that increases the rate of a reaction, whilst remaining chemically unchanged at the end of reaction

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• As catalyst will be chemically unchanged, mass of catalyst will stay the same

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ENERGY LEVEL DIAGRAM:

Diagram showing Effect of Catalyst on Rate of a Reaction

3.13: Know that a Catalyst Works by Providing an Alternative pathway with Lower Activation Energy

CATALYST: Substance that increases the rate of a reaction whilst remaining chemically unchanged at the end of reaction

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• Catalyst provides an alternative pathway requiring lower activation energy, therefore more colliding particles will have the necessary activation energy to react
• This allows more frequent successful collisions to occur, increasing the rate of reaction

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ENERGY LEVEL DIAGRAM:

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ACTIVATION ENERGY WITHOUT CATALYST:

Graph showing the Energy Level Diagram without a Catalyst

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ACTIVATION ENERGY WITH CATALYST:

       

Graph showing the Energy Level Diagram with a Catalyst

3.14C: Draw and Explain Reaction Profile Diagrams showing △H and Activation Energy

CATALYST: Substance that increases the rate of reaction white remaining chemically unchanged at the end of reaction

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• Catalyst will provide an alternative pathway requiring lower activation energy, therefore more colliding particles will have necessary activation energy to react
• This allows more frequent successful collisions to occur, increasing the rate of reaction

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ENERGY LEVEL DIAGRAM:

 

Graph showing the Effect of a Catalyst on the Activation Energy and Enthalpy Change