U1- Rates

Question 1

*activation energy

Answer 1

the minimum amount of energy required for a reaction to take place

Question 2

rate of reaction

Answer 2

the change in concentration of a reactant or product per unit time

Question 3

temperature

Answer 3

measure of the kinetic energy of the particles in a substance

Question 4

catalyst

Answer 4

a substance which speeds up a chemical reaction by lowering the activation energy, remaining unchanged by the reaction

Question 5

Maxwell-Boltzmann Distribution Curve

Answer 5

a graph showing the distribution of energy across a sample of particles

Question 6

average rate of reaction

Answer 6

the change in concentration of a reactant or product per unit time as measured over a certain time period. (change in quantity)/(change in time)

Question 7

reversible reaction

Answer 7

a chemical reaction that can occur in either the forward or reverse direction, given appropriate conditions

Question 8

closed system

Answer 8

a system in which no substances can be escape or be added

Question 9

dynamic equilibrium

Answer 9

a situation in which the rate of the forward and reverse reactions are equal resulting in no observable changes over time

Question 10

yield

Answer 10

the amount of product produced

Question 11

position of equilibrium

Answer 11

an evaluation of the relative amount of products compared to reactants, at equilibrium.
on the right if more products are present
on the left if more reactants are present

Question 12

Le Chatelier’s Principle

Answer 12

a system at equilibrium has a tendency to partially oppose a disruption

Question 13

collision theory

Answer 13

for a successful collision to occur, reactant particles must collide with the correct orientation and sufficient energy (= or > Ea)

Question 14

factors affecting rates of reaction

Answer 14

surface area (solids)
temperature
concentration
pressure (gas)
catalyst

Question 15

Boyle’s Law

Answer 15

a decrease in volume will increase the pressure

an increase in volume will decrease the pressure

Question 16

how does the use of catalysts affect the rate of reaction

Answer 16

catalysts lower the activation energy of reactants, increasing the proportion of particles with energy equal to or greater than the activation energy. This increases the frequency of successful collisions therefore increasing rate of reaction.

overall reaction is unchanged hw chemical pathway is altered.

Question 17

homogeneous vs heterogenous catalyst

Answer 17

homogeneous= same state as reactants
heterogenous= different state to reactants

Question 18

how does an increase in surface area affect rate of reaction

Answer 18

(SA is increased)
more particles are exposed to the other reactant(s) and the collision frequency increases.
There is a greater frequency of successful collisions between particles
The rate of reaction increases

Question 19

how does an increase in temperature affect the rate of reaction

Answer 19

the average kinetic energy increases
resulting in a greater proportion of particles having energy equal to or greater than the activation energy
resulting in a higher proportion of successful collisions, and thus a higher frequency of successful collisions
therefore rate of reaction increases

Question 20

how does an increase in concentration/pressure affect the rate of reaction

Answer 20

[as volume decreases (pressure)] there is a higher number of reactant particles per unit volume
increasing the collision frequency
there is a greater frequency of successful collisions between particles
the rate of reaction increases

Question 21

activated complex

Answer 21

unstable arrangement of atoms bw reactants and arrangement of products

Question 22

positive delta H

Answer 22

endothermic reaction

Question 23

negative delta H

Answer 23

exothermic reaction

Question 24

enthalpy

Answer 24

chemical energy

Question 25

haber process

Answer 25

N2 + 3H2 < - > 2NH3
400-450 degrees
200atm
Iron catalyst