Chemical reactions

Question 1

Define rate of reaction

Answer 1

The speed of reaction - tells us how rapidly the products are formed from the reactants

Question 2

Describe a suitable method to investigate the effect of a given variable on the speed of reaction

Answer 2

Catalyst: Repeat experiment twice, once with a catalyst and once without
SA: Use different sized reactants (Magnesium strips, magnesium chips, magnesium powder)

Question 3

Describe and explain the effects of temperature in terms of collisions between reacting particles

Answer 3

Temperature: Increasing the temperature of will give the particles more kinetic energy, so the frequency of collisions between particles will increase and the number of successful collisions will also increase.

Question 4

Describe and explain the effects of concentration in terms of collisions….

Answer 4

Concentration: Increasing concentration increases rate of reaction. The reason for this is increasing the concentration results in there being more particles in each cm3 of space, so there will be more frequent collisions between particles.

Question 5

Describe the application of the above factors to the danger of explosive combustion with fine powders (e.g. flour mills)

Answer 5

Flour Mills: Flour particles have a large surface area. If there is a lot of flour dust in the air, a spark from the machine is enough to cause a reaction between the flour and the spark to form an explosion.

Question 6

Describe the application of the above factors to the danger of explosive combustion with gases (e.g. mines).

Answer 6

Coal Mines: In a coal mine, there are all sorts of flammable gases in the air. At the right concentration, these gases form an explosive mix with the air, and this is enough to set off an explosion.