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Flashcards in Rates Of Reaction Deck (12):

Surface area

A greater surface area means a larger number of particles can collide with each other so there will be more reactive collisions per same unit of time.



High concentration means that there are more reactant particles in the same space of the same volume causing a faster reaction.



Temperature = average kinetic energy
• The higher the temperature the more energy each of the particles will have therefore....
-there will be more collisions because they are moving faster
-more particles will have enough energy to make the collision successful



Increased pressure reduces the volume in which the reactants are and this brings particles close together resulting in more reactive collisions



They provide an alternative reaction pathway which has a lower activation energy without getting used up


Activation energy + graph

The amount of energy needed for particles to collide successfully.
Reactants (Less stable, more energy) = Products (more stable, less energy)


Collision theory

- all particles are moving
- all particles have Kinetic energy
- particles must collide
- each collision must have a minimum energy to react
• concentration, surface area, temperature, pressure


Experiments on the concentration

- The effects on concentration of sodium thiosulfate
• put 50 cm cubed of sodium thiosulfate in a cronical flask
• measure 5cm of dilute hydrochloric acid and add it to the flask
• Measure the time it takes for the cross to disappear
• repeat with different measurements of water


Experiments on the surface area

- The effect on the volume of gas produced on the surface area of marble chips
• add different sizes of marble chips and see which size produces 100 cm cubed of gas the quickest when you react it with dilute hydrochloric acid


Experiments on temperature

- The effect of temperature on the reaction between hydrochloric acid and calcium carbonate
• heat the solution to 20° C then 30° C and 40° C and record how long it takes for a gas cylinder to fill up to 100 cm cubed of gas.
• use a spatula of calcium carbonate and 50 cm³ of hydrochloric acid


Effect of light

Increasing the intensity of light will increase the rate of someone reactions like photosynthesis and photography where the photographic film is coated with chemicals that react when in contact with the light.


Catalyst examples

- phosphoric acid
- Silica or alumina
- iron
- vanadium