physical chemistry - rates of reaction

Question 1

5 ways to increase rate of reaction

Answer 1

• using a catalyst
• increase surface area
• increase concentration
• increase pressure
• increase temperature

Question 2

how does increasing surface area increase rate of reaction?

Answer 2

• more particles exposed
• more frequent collisions

Question 3

how does increasing the concentration of a solution or pressure increase rate of reaction

Answer 3

• more particles in the same space
• more frequent collisions

Question 4

how does increasing temperature increase rate of reaction

Answer 4

• particles have more kinetic energy
• more frequent collisions
• more successful collisions as collision energy is greater or equal to activation energy

Question 5

what is a catalyst

Answer 5

a substance that increases the rate of reaction by providing an alternative pathway with lower activation energy, but it itself remains chemically unchanged

Question 6

investigate the effect of changing the surface area of marble chips and of changing the concentration of hydrochloric acid on the rate of reaction between marble chips and dilute hydrochloric acid

Answer 6

• add calcium carbonate marble chips to a beaker containing dilute hydrochloric acid
• use cotton wool on the mouth of the beaker
• measure the mass of all of it using a balance
• record the change in mass as the calcium carbonate reacts with the acid to form carbon dioxide and calcium chloride.
• record results
• repeat experiment but with larger marble chips
• larger chips means less surface area, so notice how the rate of reaction is slowed.
• repeat experiment again but with half the concentration of acid
• the reaction is much slower and produces half the carbon dioxide

Question 7

how to calculate rate of reaction

Answer 7

amount of reactant used or amount of product formed/time