Making Reactions go Faster 3

Question 1

how does a catalyst work in the first place

Answer 1

• by providing an alternate route for a reaction
• this route has a lower activation energy for the reaction to occur
• thereby making it ‘easier’

Question 2

if you have a maxwell-botlzmann distribution graph , where would the activation energy mark with a catalyst be compared to the normal activation energy mark and why

Answer 2

• to the left of the normal one
• because a higher proportion of the molecules will be able to react without their energy levels changing
• due to an alternative reaction pathway allowing for lower activation energies

Question 3

what would the reaction profile for an exothermic reaction reaction simply look like

Answer 3

• there would be a horizontal line showing the energy level of the reactants
• a curve would then go from this line to a level below the horizontal line
• where a new horizontal line showing the energy level of the products would be drawn

Question 4

what is a reaction profile showing, using its axis

Answer 4

the enthalpy of a reaction over the progression of the reaction

Question 5

what would the reaction profile for an exothermic reaction therefore be telling us

Answer 5

that the energy level of the products is less than the energy level of the reactants

Question 6

what arrow would be drawn on an exothermic and endothermic reaction profile to show the activation energy

Answer 6

• for exo it would be an arrow from the reactant line to the peak of the curve
• for endo it would be an arrow from the product line to the peak of the curve

Question 7

what would the vertical distance between the reactants and the products be called and labeled

Answer 7

the enthalpy change of the reaction , delta H

Question 8

what would be the difference between the reaction profile for a catalysed and uncatalysed reaction

Answer 8

• the catalysed reaction would have a shorter curve than the uncatalysed one
• indicating less activation energy being required for the reaction to take place

Question 9

what are the two main economic advantages of using catalysts

Answer 9

• they increase the rate of a chemical reaction so more product can be made in a given time
• the reaction can take place at lower temps so the energy costs are lower

Question 10

what type of catalyst is commonly used in industry

Answer 10

heterogenous catalysts

Question 11

what is a heterogenous catalyst

Answer 11

one that is in a different phase to that of the reactants

Question 12

what do solid catalysts do

Answer 12

• they provide a surface which the gas molecule can adsorb then react
• the product molecules then desorb from the surface and more reactant particles take their place

Question 13

what is a catalyst

Answer 13

• a substance that increases the rate of a reaction

- without chemically changing throughout the process