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Speed of Reaction :checkered_flag: (Measuring speed of reaction (if…
Speed of Reaction :checkered_flag:
Measuring speed of reaction
if reaction is exothermic or endothermic
temperature vs. time
if product is insoluble and reactant is in aqueous state
precipitate formed vs. time
if reaction products are different in colour to reactants
Change in Colour vs. Time
if reaction involves neutralisation of acid and alkali
change in pH vs. time
if reaction produces gas as product
Change in volume/pressure vs. Time
if gas produced is allowed to escpae
mass of mixture vs. Time
if gas produced is allowed to escpae
mass of mixture vs. Time
Factors that affect speed of a chemical reaction (increase speed--> )
Temperature
increase in temperature
increase rate of reaction
increase in kinetic energy of the particles
particles collide more frequently, more energized
Concentration of a solution
increase of concentration
more particles contained per unit volume
particles are closer together and therefore collide more frequently
increase of frequency of effective collisions
Pressure
increasing the pressure will increase the rate of the reaction
increasing the pressure of a gas forces the particles closer together
Because the particles are closer together, they collide more frequently
increasing the frequency of effective collisions increases the rate of the reaction
Surface area of a solid
increasing the surface area of a solid will increase the rate of reaction
increasing the surface area of a solid reagent increases the area over which collisions between the two reacting chemicals can take place
this increases the frequency of the collisions between the two reagents
increasing the frequency of effective collisions increases the rate of reaction
Catalyst
reduces activation energy of a reaction by allowing the reaction to take place via an alternative pathway
By lowering the activation energy, more collision between particles will have sufficient energy for a reaction to take place
Examples
Iron (Fe) - Haber process
Nickel (Ni) - Catalytic hydrogenation of plant oils during manufacturing of margarine
Vanadium (V) Oxide (V2O5) - Manufacture of sulfuric acid
Biological catalysts (Enzymes)
Increase the speed of reactions that take place inside living organisms
Sensitive to variables such as pH and temperature
Collision Theory
During a chemical reaction...
Reacting Chemicals collide with each other
They must collide with energy ≥ activation energy
They must also collide in the correct orientation