C6 Rate of Chemical Change

Question 1

Calculating the rate of reaction (g/s or cm3/s)

Answer 1

Quantity of reactant/product (g or cm3)

Time (s)

Question 2

Why do chemical reactions occur?

Answer 2

Reacting particles collide with each other and with sufficient energy

Question 3

What is the minimum amount of energy required when particles collide called?

Answer 3

Activation energy

Question 4

Why does an increased concentration cause a faster reaction?

Answer 4

There are more particles in the same volume so there are more frequent collisions

Question 5

Why does an increased pressure cause a faster reaction?

Answer 5

The particles are closer together so there are more frequent collisions

Question 6

Why does an increased surface area cause a faster reaction?

Answer 6

There are more particles available to collide so there are more frequent collisions

Question 7

Why does an increased temperature cause a faster reaction?

Answer 7

The particles move faster so there are more frequent collisions and the collisions are harder so more reach the activation energy

Question 8

Why does using a catalyst cause a faster reaction?

Answer 8

A catalyst provides an alternative reaction pathway with a lower activation energy. Catalyst is not used up in the reaction

Question 9

What is equilibrium?

Answer 9

In a closed system equilibrium is reached when the forward and reverse reactions occur at exactly the same rate

Question 10

What is Chatilier’s principle?

Answer 10

If a system is at equilibrium and a change is made to any of the conditions the reaction will respond to counteract the change.

Question 11

What is the affect of increasing the concentration of the reactants on the position of equilibrium?

Answer 11

The position of equilibrium shifts to the right and the yield of products is greater

Question 12

What is the affect of increasing the concentration of the products on the position
of equilibrium

Answer 12

The position of equilibrium shifts to the left and the yield of the reactants is greater

Question 13

What is the rule for increasing pressure?

Answer 13

If pressure is increased equilibrium will shift to the side with

Question 14

What is the rule for increasing temperature?

Answer 14

If temperature is increased equilibrium will shift in the endothermic direction to reduce the temperature

Question 15

What is the rule for decreasing temperature?

Answer 15

If temperature is decrease equilibrium will shift in the exothermic direction to increase the temperature