rates of reaction

Question 1

why do reactions slow down towards the end?

Answer 1

fewer molecules are able to react

Question 2

rate of reaction formula

Answer 2

quantity of product formed / time taken

quantity of reactant used / time taken

Question 3

how do you use a tangent to determine the rate of reaction?

Answer 3

• a straight line touching the curve on the point you want to find the rate of reaction at (on the time axis usually)
• then a triangle is drawn using the tangent
• the length of the triangle sides can be measured using the x and y axis
  to calculate the rate of reaction, we can then do y/x

Question 4

what is collision theory?

Answer 4

collision theory = a reaction can only take place when the reacting particles collide with each other with sufficient energy

Question 5

what is the rate of a reaction?

Answer 5

rate = number of successful collisions per second

Question 6

why does concentration increase the rate

Answer 6

concentration increases the rate because there are more particles to collide with each other

Question 7

what is the problem and solution

Question 8

why does surface area affect rate?

Answer 8

smaller blocks of reactant have a greater surface area:volume ratio, meaning there is more surface area available for other particles to collide with

Question 9

why does temperature affect rate ?

Answer 9

Increasing temperature increases the energy of the particles, meaning they collide faster and with more energy.
this increases the number of successful collisions

Question 10

equilibrium

Answer 10

equilibrium = at some point, the forward and backward reactions will take place at exactly the same rate in a sealed container

Question 11

reversible reactions

Answer 11

• direction can be changed by changing the conditions
• if a reversible reaction is exothermic in one direction, it is endothermic in anothe

Question 12

copper sulfate reversible reaction

Answer 12

for example, hydrated copper sulfate (blue) <=> anhydrous copper sulfate (white) + water

you just need to add water to reverse it. energy is released in the reverse reaction, meaning it is exothermic.

Question 13

what is Le Chatelier’s principle?

Answer 13

if a system is at equilibrium and a change is made to the conditions then the system responds to counteract the change.

Question 14

how does changing concentration change the reversible reaction?

Answer 14

if the concentration of reactants is increased, more products will be created until the reaction has reached equilibrium again

Question 15

temperature and reversible reactions

Answer 15

If we increase the temperature of the system, the equilibrium will shift towards the endothermic side to reduce the temperature.

Question 16

pressure and reversible reactions

Answer 16

on a reversible reaction at equilibrium, the position of the equilibrium shifts to the side with less molecules

if the number of molecules is the same on both sides, changing the pressure has no effect