Controlling the Rate Flashcards
(24 cards)
Equation to Calculate time
1
——
t
why do reaction rates must be controlled in industrial processes?
to ensure that processes are:
- economically viable/ worth it (result in a good amount of produce and profits for the company)
- safe (the reaction does not occur too quickly which could result in an explosion)
Rate of Reaction from graphs of a changing property versus time equation?
🔺Quantity
———————
🔺Time
Effects of Concentration on Reaction Rate:
increases the number of reactant particles which increases the chances of collision so the rate increases
Effects of Pressure on Reaction Rate:
increases the concentration of reactants within a more compacted space which increases the chances of collision, so the rate increases
Effects of Particle Size on Reaction Rate:
smaller reactant particles provide a greater surface area which increases the chances for particle collisions so the reactant increases
Effects of Temperature on Reaction Rate:
increases kinetic energy of particles, which increases chances of collisions, so rate increases
Collision Geometry:
for a successful collision to take place, the collision geometry needs to be right so that the atoms are facing the right way; so an activated complex can be formed
🔺 🟢
| ⬅️➡️ | POTENTIAL SUCCESSFUL
🔺 🟢 COLLISION GEOMETRY
🔺-🔺 🟢-🟢 UNSUCCESSFUL COLLISION
GEOMETRY
What does a potential energy diagram show?
the energy pathway for a reaction
what is the enalthpy change?
the energy difference between reactants and products (🔺H)
- the change in energy for a reaction
EQUATION: Products - Reactants
Exothermic reaction energy level diagram:
- the products are at a lower energy than the reactants
ENALTHPY CHANGE = -ve
Endothermic reaction energy level diagram:
- the products are at a higher energy than the reactants
ENALTHPY CHANGE = +ve
Definition of Activation Energy:
the minimum energy required for a reaction to occur
- energy gathered by colliding molecules
Definition of Activation Complex:
the unstable arrangement of atoms formed at the max of the potential energy barrier (tip of the curve on the graph)
Activation Energy Equation:
PE - PE
Activated Complex) - (Reactants
What does a catalyst provide?
an alternative energy pathway with a lower activation energy
- resulting in the activated complex on the graph being at a lower level
What is temperature a measure of?
the average kinetic energy of the particles in a substance
Effect of changing temp on kinetic energy and reaction rate:
the higher the temp the more kinetic energy gained meaning the particles hit off the sides more often at a greater force, increasing the chances of collision, therefore increasing reaction rate
Effect of adding a catalyst to reaction with increasing temp:
the average kinetic energy of the molecules stay the same but the required Activation Energy decreases due to the presence of a catalyst
Solubility of Ionic Compounds:
most soluble in polar solvents eg. water, because ions of the solid are strongly attracted to the polar solvent molecules
Solubility of Polar Compounds:
most soluble in polar solvents eg. water, because ions of the solid are strongly attracted to the polar solvent molecules
Solubility of Non- Polar Compounds:
not likely to dissolve in polar solvents eg water, more likely to dissolve in non polar solvents eg hexane ( hydrocarbons)
Why do polar molecules have high melting/ boiling points?
due to the presence of PD-PD forces (strongest type of bonding force)
more energy required to break bonds between polar molecules
What needs or happen for a collision to be successful?
- correct geometry ( atoms to be facing the right way)
- Correct Activation Energy ( energy required for reaction to occur)
