Controlling the Rate

Question 1

Equation to Calculate time

Answer 1

1
——
t

Question 2

why do reaction rates must be controlled in industrial processes?

Answer 2

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)

Question 3

Rate of Reaction from graphs of a changing property versus time equation?

Answer 3

🔺Quantity
———————
🔺Time

Question 4

Effects of Concentration on Reaction Rate:

Answer 4

increases the number of reactant particles which increases the chances of collision so the rate increases

Question 5

Effects of Pressure on Reaction Rate:

Answer 5

increases the concentration of reactants within a more compacted space which increases the chances of collision, so the rate increases

Question 6

Effects of Particle Size on Reaction Rate:

Answer 6

smaller reactant particles provide a greater surface area which increases the chances for particle collisions so the reactant increases

Question 7

Effects of Temperature on Reaction Rate:

Answer 7

increases kinetic energy of particles, which increases chances of collisions, so rate increases

Question 8

Collision Geometry:

Answer 8

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

Question 9

What does a potential energy diagram show?

Answer 9

the energy pathway for a reaction

Question 10

what is the enalthpy change?

Answer 10

the energy difference between reactants and products (🔺H)

• the change in energy for a reaction

EQUATION: Products - Reactants

Question 11

Exothermic reaction energy level diagram:

Answer 11

• the products are at a lower energy than the reactants

ENALTHPY CHANGE = -ve

Question 12

Endothermic reaction energy level diagram:

Answer 12

• the products are at a higher energy than the reactants

ENALTHPY CHANGE = +ve

Question 13

Definition of Activation Energy:

Answer 13

the minimum energy required for a reaction to occur

• energy gathered by colliding molecules

Question 14

Definition of Activation Complex:

Answer 14

the unstable arrangement of atoms formed at the max of the potential energy barrier (tip of the curve on the graph)

Question 15

Activation Energy Equation:

Answer 15

PE - PE

Activated Complex) - (Reactants

Question 16

What does a catalyst provide?

Answer 16

an alternative energy pathway with a lower activation energy

• resulting in the activated complex on the graph being at a lower level

Question 17

What is temperature a measure of?

Answer 17

the average kinetic energy of the particles in a substance

Question 18

Effect of changing temp on kinetic energy and reaction rate:

Answer 18

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

Question 19

Effect of adding a catalyst to reaction with increasing temp:

Answer 19

the average kinetic energy of the molecules stay the same but the required Activation Energy decreases due to the presence of a catalyst

Question 20

Solubility of Ionic Compounds:

Answer 20

most soluble in polar solvents eg. water, because ions of the solid are strongly attracted to the polar solvent molecules

Question 21

Solubility of Polar Compounds:

Answer 21

most soluble in polar solvents eg. water, because ions of the solid are strongly attracted to the polar solvent molecules

Question 22

Solubility of Non- Polar Compounds:

Answer 22

not likely to dissolve in polar solvents eg water, more likely to dissolve in non polar solvents eg hexane ( hydrocarbons)

Question 23

Why do polar molecules have high melting/ boiling points?

Answer 23

due to the presence of PD-PD forces (strongest type of bonding force)

more energy required to break bonds between polar molecules

Question 24

What needs or happen for a collision to be successful?

Answer 24

• correct geometry ( atoms to be facing the right way)

- Correct Activation Energy ( energy required for reaction to occur)