Writing Frames

Question 1

Temperature in rate of reactions

Answer 1

Increasing temperature causes particles to absorb heat energy and move faster. This will increase the force at which particles collide, causing more effective and successful collisions per second, because they absorb heat energy which exceeds the required activation energy and the gap is bridged. The faster moving particles will encounter each other and collide more frequently per second. This will increase the number of effective and successful collisions per second, causing the rate of reaction to increase.

Question 2

Concentration in rate of reactions

Answer 2

Increased concentration means there are more reactant particles available per unit volume. This leads to more particles being available to collide, with sufficient energy and in the correct orientation. This increases the frequency of effective and successful collisions per second, causing the rate of reaction to increase.

Question 3

Surface area for rate of reactions

Answer 3

Larger surface areas will cause larger numbers of particles to be exposed. This means that there will be a greater chance of effective and successful collisions taking place per second. This causes the rate of reaction to increase.

Question 4

Catalysts for rate of reactions

Answer 4

Catalysts provide an alternate pathway for a reaction to proceed, by lowering the activation energy needed for the particles to effectively and successfully collide. However, catalysts do not directly affect the products and reactants, nor are used up in the reaction. They only help the reaction occur faster.

Question 5

Large Kc value

Answer 5

If the Kc value is large (>1), then there is a higher [products] compared to [reactants]. This means that the forward reaction is being favoured and equilibrium lies to the right hand side.

Question 6

Small Kc value

Answer 6

If the Kc value is small (<1), then there is a higher [reactants] compares to [products]. This means that the backward reaction is being favoured and equilibrium lies to the left hand side.

Question 7

Concentration increasing in equilibrium

Answer 7

If the [R] is increased, the equilibrium of the system is disturbed. The system will respond by using up the extra R. This will favour the forward reaction and the [P] will increase, to restore equilibrium.

Question 8

Concentration decreasing in equilibrium

Answer 8

If the [R1] is decreased, the equilibrium of the system is disturbed. The system will respond by making more R1. This will favour the backward reaction and the [P’s] will decrease, while the [remaining R’s] increase, to restore equilibrium.

Question 9

Temperature in equilibrium

Answer 9

If the temperature is increased, the equilibrium of the system is disturbed. The system will respond by using up the added heat. This will favour the endothermic (forward/backward) reaction and therefore more [___] will form, while there will be less [___], because they will be used up in the reaction, to restore equilibrium.

Question 10

Pressure in equilibrium

Answer 10

If the pressure is increased, the equilibrium of the system is disturbed. The system will respond by decreasing pressure. This will favour the reaction that produces a less number of moles, which is the (forward/backward) reaction. Therefore, the [___] will increase, to restore equilibrium.

Note: this is only for gases

Question 11

Catalyst in equilibrium

Answer 11

Catalysts can speed up the time it takes for equilibrium to be reached, but does not directly affect equilibrium.