kinetics exam qs

Question 1

Explain why it is important to clean the surface of this magnesium ribbon when
investigating the rate of its reaction with hydrochloric acid

Answer 1

The magnesium is coated with an oxide / MgO

Question 2

Magnesium ribbon reacts with hot water. Heated magnesium ribbon reacts with steam.
State two differences between these reactions.

Answer 2

faster with steam
bright white light

Question 3

Pure magnesium reacts completely with an excess of dilute sulfuric acid.
The reaction of pure calcium with an excess of dilute sulfuric acid is very rapid initially.
This reaction slows down and stops before all of the calcium has reacted.
Use your knowledge of the solubilities of Group 2 sulfates to explain why these reactions of
magnesium and calcium with dilute sulfuric acid are so different.

Answer 3

Magnesium sulfate is soluble and calcium sulfate is insoluble. Calcium sulfate coats the surface of the calcium. prevents further contact with the acid

Question 4

Give the meaning of the term catalyst

Answer 4

speeds up a reaction but is chemically unchanged at the end