Reaction Rates

Question 1

Catalyst

Answer 1

Provides an alternate mechanism with a lower overall activation energy, is an active participant which is regenerated in later step of the reaction mechanism

Question 2

Activation energy

Answer 2

The minimum energy a particle needs to have a successful collision

Question 3

Rate determining step

Answer 3

The slowest step of the reaction

Question 4

Reaction Mechanisms

Answer 4

The sequence of elementary steps by which a chemical reaction occurs

Question 5

Reaction Intermediate

Answer 5

An ordinary chemical species which is produced during one step of a reaction and used up in a subsequent step of the reaction.

Question 6

Activated complex

Answer 6

A short-lived, unstable species which only exists after the reactants have received an energy equal to the activation energy.

Question 7

Types of reaction rates

Answer 7

1. Colour intensity/time
2. Temp/time
   3, Pressure/time (closed system)
3. Mass/time

Question 8

What increases reaction rates

Answer 8

1. Temperature
2. Concentration
3. Pressure (inversely proportional to volume, proportional to concentration)
4. Nature of reactants (more bonds/stronger bonds = slower reaction time, also depends on how loosely valence e- are held)

Question 9

Homogenous

Answer 9

All reactants are in the same phase, surface area does not affect homogenous reactions
1. two gases
2. two substances both dissolved in water
3. two liquids both dissolved in each other
two solids don’t count

Question 10

Closed system reaction rate

Answer 10

Matter cant leave/enter system (use gas pressure/time)

Question 11

Open system reaction rate

Answer 11

Matter can enter/leave system (use mass/time bc of loss of gas)

Question 12

Inhibitor

Answer 12

A chemical that reduces a reaction rate by combining with a catalyst or one of the reactants to prevent the reaction from occurring, e.g antibiotics

Question 13

Reaction Rate

Answer 13

Amount of product formed/time

Question 14

Heterogenous

Answer 14

A reaction in which reactants are in different phases (e.g two liquids that are immiscible/dont dissolve)

Question 15

Collision Theory

Answer 15

1. Particles must collide for a reaction
2. Not every reaction is successful, it depends on energy requirements and geometry

Question 16

Bond Energies

Answer 16

Potential energy decreases after atoms form a bond bc they give off energy and become more stable. Attractive forces and repulsive forces balance each other out.
As two reactant particles approach eachother, the valence e- repulse each other and slows them down (KE decrease, PE increase)

Question 17

Potential Energy

Answer 17

PE is directly related to the energy of the electrons in the chemical bonds/the number and types of atoms in the molecules

Question 18

Kinetic Energy

Answer 18

The energy which a system possesses bc of movement within the system.

Question 19

Enthalpy

Answer 19

the total kinetic and potential energy which exists in a system when at constant pressure

Question 20

Energy of reaction rate rule of thumb

Answer 20

For a slow reaction, a 10C degree increase doubles the rate

Question 21

Activated complex formula

Answer 21

All the atoms of the product side are grouped together into elements, the charges are combined (e.g ClO3- + Cl- = Cl2O3 2-).

Question 22

Elementary processes

Answer 22

Steps in a reaction

Question 23

Acid Catalyzed

Answer 23

If H ion is a reactant

Question 24

Catalyst effects

Answer 24

Enthalpy of the overall reaction is the same for both catalyzed and uncatalyzed reaction, only intermediate reaction details are affected. Both intermediate species and catalysts cancel out.

Question 25

How phase affects reaction rate

Answer 25

Aqueous > gases/liquids > solids

Question 26

PE vs time graph

Answer 26

slow reaction rates = higher activation energy hill

Question 27

of molecules vs KE graph

Answer 27

funny normal distributions (ew). At a given temp, some molecules react and some don't, so there must be a continuous distribution of energies among the molecules. The cutoff line is the activation energy.