Rates Of Reactions Flashcards
To measure the effects of changes in surface area, concentration of solutions temperature and the use of a catalyst, you can…
React calcium carbonate marble chips with dilute hydrochloric acid and measure the mass (or volume) of CO2 produced by weighing the difference in mass of the reactants and the difference in mass of the products. Plot the results on a graph with mass against time and you’ll get an upward curve
For a reaction between calcium carbonate marble chips and HCl to occur…
Acid particles must collide with the surface of the marble chips. As the acid particles get used up the collision rate decreases do the reaction slows down.
If you increase the surface area of marble chips in a reaction but keep the mass the same…
The reaction will happen faster (but the amount of CO2 produced is the same) as there is more SA in contact with the gas or liquid and collisions are much more likely to happen
If you use HCl half as dilute as normal in a reaction with calcium carbonate…
The reaction. Happens slower and produces half as much Carbon dioxide gas
In terms of the collision theory, if you increase the concentration of the reactants…
The reaction becomes faster because it increases the frequency of collisions per second
If you do experiments at higher temperatures…
There is more kinetic energy for particles so they move faster and collide more frequently, the the rate of reaction is sped up, although the total products produced are the same
… Collisions break and make new bonds
Not all (some particles just bounce off each other)
In order for a reaction to happen, particles have to…
Collide with the minimum amount of energy called activation energy
Changing the pressure of a reaction where the reactants are only solids or liquids…
Makes practically no difference
Increasing the pressure in a reaction between gases…
Speeds the reaction up as it forces the particles closer to one another
Catalysts…
Speed up the rate of reactions but aren’t used up in the process.
Adding a catalyst gives the reaction…
An alternative route for reactions with a lower activation energy (but does not lower the activation energy)
