Reaction Rates

Question 1

Rate of reaction

Answer 1

The change in concentration per unit time of any reacted or product

Rate is proportional to the slope of the line.

Question 2

Average rate

Answer 2

The rate over the entire time of the reaction from start to finish

Volume/time= ar cm^3 per (unit time)

Question 3

Instantaneous rate

Answer 3

The rate at a particular point in the reaction

Slope thang

Question 4

Factors that affect rate of reaction

Answer 4

Concentration
/at higher conc. there are more particles. This means there can be more collisions with enough energy

Temperature
/at highe temperatures particles move faster. This means they are more likely to collide with enough energy.

Particle size
/smaller particles react faster as there are more particles free to collide

Catalyst
/a catalyst reduces the amount of avtivation energy needed.

Nature of reactants
/covalent - substances react slowly because chemical bonds need to be broken before new ones can be made.
/ionic - substances react quickly because there are no chemical bonds to be broken before new ones are made.

Question 5

Collision Theory

Answer 5

For a chemical reaction to take place particles must collide with enough energy

Question 6

Activation energy

Answer 6

The amount of energy needed for a reaction to take place

Question 7

Catalyst

Answer 7

A substance that alters the rate of a chemical reaction but is not used up at the end of the reaction

Question 8

Types of catalysts

Answer 8

Homogeneous
/same phase
//potassium iodide -> hydrogen peroxide (both liquid)

Heterogeneous
/reactants and catalysts are different phases
//catalytic oxidation of methanol by hot platinum

Autocatalysis
/when one of the products catalyses the reaction
//permanganate ions -> Fe^+2

Question 9

Exothermic and endothermic

Answer 9

Has initial energy
Has lower energy

At the beginning (reactant)

Question 10

Enzymes: biological catalysts

Answer 10

Catalase
/decomposes H2O2 in living things

Lysozyme
/catalyses the breakdown of cellwalls in bacteria

Hydrolases
/catalyses the breakdown of fats,proteins and carbs.

Question 11

Catalytic converters

Answer 11

Help to reduce pollution from car exhausts

Platinum -> hydrocarbons
Palladium -> CO
Rhodium -> NO

NO2

Question 12

Catalyst poisons

Answer 12

Lead

Pb in petrol is a catalytic poison and rapidly stops the catalyst from working