topic 9: kinetics 1

Question 1

describe how an increase in temperature effects the Maxwell-Boltzmann distribution

Answer 1

peak of curve moves right and down with greater area past activation energy mark

Question 2

explain how increasing concentration increases rate of reaction

Answer 2

more particles in a givern volume so the particles will collide more frequently. this means there is more chance for the reaction to occur

Question 3

explain how increasing pressure increases rate of reaction

Answer 3

more particles in a givern volume so the particles will collide more frequently. this means there is more chance for the reaction to occur

Question 4

explain how using a catalyst increses the rate of reaction

Answer 4

the activation energy is decreased due to an alternate reaction pathway. more of the reactant particles have this energy so a greater proportion can react, increasing rate of reaction

Question 5

define reaction rate

Answer 5

the change in amount of reactant or product per unit time

Question 6

what is a heterigeneous catalyst

Answer 6

a catalyst in a different phase to the reactant. the reaction happens on the surface of the catalyst

Question 7

explain how solid heterogeneous catalysts work

Answer 7

reactant molecules bond with the surface of the metal catalyst. (adsorption)
bonds between reactant molecule atoms are weakened and broken forming radicals.
radicals react to form new molecules.
new molecules detach from the catalyst. (desorption)

Question 8

what is a homogeneous catalyst

Answer 8

a catalyst in the same physical state as the reactant. reactants combine with the catalysts to make an intermediate species, which then react to form the products and reform the catalyst

Question 9

describe the reaction profile of a reaction with a homogeneous catalyst

Answer 9

instead of one inistial hump followed by a decrease in energy, there are two smaller humps. the first is the activation energy required for intermediates to form and the second is the activation energy required for the products to form

Question 10

explain how the maxwell-boltzmann distribution shows how catalysts work

Answer 10

activation energy is reduced so a greater area under the graph is positioned beond the line. this means more of the reactant particles have greater than the activation energy and can react. rate of reaction increases

Question 11

give two benifits of a catalyst

Answer 11

temperature can be reduced to save money and preserve benefitial equilibrium
catalysts can change the properties of the products making them more useful