the rate and extent of chemical changes

Question 1

how to work out rate of reaction

Answer 1

amount of product (reactant) used up/ time
(mol/s, g/s, cm^3/s)

Question 2

factors that affect rate of reaction

Answer 2

• concentration
• surface area
• pressure
• temperature
• catalysts

Question 3

what is collision theory?

Answer 3

chemical reactions only occur when reactant particles collide with sufficient energy to react

Question 4

what is activation energy?

Answer 4

minimun energy particles need to react

Question 5

when concentration increases…
(and why!)

Answer 5

• rate of reaction increases
• PROPORTIONAL
• more particles in smaller vol-> more collisions per second -> more frequent successful collisions

more particles per unit vol

Question 6

when pressure increases…
(and why!)

Answer 6

• rate of reaction increases
• same no particles in smaller vol -> more collsions per second -> more frequent successful collisons

Question 7

when surface area increases…
(and why!)

Answer 7

• rate of reaction increases
• PROPORTIONAL
• greater surface area of particles exposed to other reactants-> more collsions per second-> more frequent successful collisions

Question 8

when temperature increases…
(and why!)

rate of reaction

Answer 8

• rate of reaction increases
• more kinetic energy in particles -> more collsions per second -> more frequent successful collsions

Question 9

what is a catalyst and how?

Answer 9

• speeds up rate of reaction without being changed or used up in the reaction
• lowers activation energy

Question 10

high activation energy in a reaction

Answer 10

lower rate of reaction
^more energy needed

Question 11

describe the system at equillibrium

Answer 11

-closed system
- rate of forward and reverse reactions are equal
- concentration of reactants and products remain unchanged

Question 12

effect of changing concentration on equilibrium

Answer 12

• of reactants- shift to products (increasing their yield)
• of products- shift to reactants (increasing their yield)

Question 13

effect of changing temperature on equilibrium

Answer 13

increase- direction of endothermic
decrease- direction of exothermic

Question 14

effect of changing pressure on equilibrium

Answer 14

increase- shift to side with less moles of gas
decrease- shift to side with more moles of gas

Question 15

le chateliers principle

Answer 15

when change made to conditions of equilibrium system- system with automatcially move to oppose chage

-temp
-pressure
-concentration