1) RATES & REACTIONS Flashcards
State collisions theory
Collisions theory states that for a successful chemical reaction to occur reactant particles must collide in the correct GEOMETRY and have the right ENERGY
How would a higher concentration affect rate
- The higher the concentration the greater the chance of collisions as you have more particles in the same space.
- As more of these particles are moving about you are more likely to have more collisions therefore faster reaction
How would a reacting power instead of lumps affect rate
- Small pieces have more surface area, hence more particles are available to react
- This results in more collisions therefore a faster reaction
How would a higher temperature affect rate
- The higher the temperature, this means more particles have more KINETIC ENERGY
- More particles have energy greater than the activation energy, meaning the particles move faster and perform more collisions. Therefore a faster reaction
How do you calculate average rate
And what are the units
Average rate =
change in quantity/change in time
UNITS:
cm3/s-1
How do you work out relative rate
And time
Rate = 1/time
Time = 1/rate
What effect would changing HCL to H2SO4 have on a rate graph
- More concentration of H ions so steeper graph
* It will make more hydrogen gas because there is twice as many H ions so higher product
What is activation energy
The minimum energy required by colliding molecules for a successful reaction
What effect does a catalyst have on activation energy
Adding a catalysts lowers the activation energy therefore increasing the number of particles with energy greater than the activation energy
What effect does increasing temperature have in activation energy
Increasing temperature will increase the number of particles with kinetic energy greater than the activation.
What sign is delta H for a exothermic reaction
Negative
What sign is delta H for a endothermic reaction
Positive
How do you work out enthalpy change for a forward and reverse reaction
Forward:
Products - reactants
Reverse:
Reactants - products
How do you work out activation energy for a reverse and forward reaction
Forward:
Reactants to tip
Reverse:
Products to tip
What is the activated complex
The state between reactants and products where new bonds are being formed and old bonds broken
The collision must have enough energy to break those bonds in order to react
