Rate of reaction Flashcards
Explain what is meant by the rate of reaction
it is the speed of the reaction.
measured by how fast a reactant is used or how fast a product is made
State the effect of surface area on rate
surface area increases = rate of reaction increases
use the collision theory to explain the effect of surface area on rate
increase in surface area = increase in surface for particle collision = more frequent collisions= more successful collisions = rate of reaction increases
what are the 3 main points of the collision theory
- particles must collide to react
- particles must have the right orientation
- particle collision must have enough energy (they must pass the activation energy)
State the effect of temperature on rate
increase temperature = increase rate
use the collision theory to explain the effect of temperature on rate
as temperature increase, particles gain more energy:
1) move faster so the frequency of collisions increases = more successful collisions
2) so they react with more energy = more likely to reach the activation energy
overall rate of reaction increases
State the effect of pressure on rate
as pressure increase = rate of reaction increases
use the collision theory to explain the effect of pressure on rate
increase pressure = increase particles in a unit of volume = more frequent successful collisions = increase the rate of reaction
what is a catalyst
a substance that speeds up the rate of reaction without being changed/used up in the reaction
explain how a catalyst works
catalyst provides an alternative pathway requiring a lower activation energy = increase the likelihood of molecules to reach the activation energy = more particles can react successfully
Describe an experiment to investigate the effect of surface area on rate
Reaction of marble chips (calcium carbonate) with hydrochloric acid (HCl) to form carbon dioxide gas and calcium chloride solution.
- start with large marble chips, then crush the marble into smaller chips, so as surface area increase, the rate of reaction increases (gas is given off faster)
IV: surface area of the marble chips
DV: mass of the contents inside the conical flask (marble chips + HCl)
CV: temperature, concentration of the HCl, initial mass of the marble
Equipment: conical flask
If with syringe, the DV is collecting the gas in the gas syringe.
Describe an experiment to investigate the effect of temperature on rate
Reaction of magnesium strip with HCl to release hydrogen gas. Measure the time taken for the magnesium to dissolve.
Investigate the different temperatures of HCl on the rate. Put HCl in different temperature water baths (eg. in ice, 30º, 60). As the temperature increase, you see the reaction go faster.
IV: temperature of the HCl
DV: time taken for the Mg to dissolve
CV: size of the Mg strip, concentration of HCl
Equipment: conical flask
Describe an experiment to investigate the effect of concentration on rate
Draw a cross on a white piece of paper. Place conical flask on top of it. Add HCl to sodium thiosulfate in the flask. Record the time taken for the cross to disappear.
Repeat and change the concentration of the HCl and observe the time taken for the cross to disappear. As concentration increase, the rate increase (time is quicker).
IV: concentration of HCl
DV: time taken for the cross to disappear
CV: concentration of sodium thiosulfate
Equipment: conical flask
Describe an experiment to investigate the effect of a catalyst on rate
Add hydrogen peroxide to a conical flask with catalyst manganese(IV) oxide. Observe the decomposition, amount of gas collected in a syringe.
IV: addition of the catalyst -manganese (IV)oxide
DV: amount of gas collected in syringe
CV: temperature, concentration of hydrogen peroxide
Equipment: conical flask, gas syringe
