C8-Rates and Equilibrium

Question 1

Collision theory

Answer 1

(An explanation)Collisions between reacting particles are required for chemical reactions to take place, these collisions must have sufficient energy (activation energy), we can increase the rate of a reaction by increasing the frequency (number)of collisions and/or the energy of reactant particles this can be achieved by changing lots of different factors

Question 2

Anhydrous

Answer 2

Describes a substance that doesn’t contain water

Question 3

Closed system

Answer 3

A system in which no matter enters or leaves but energy can

Question 4

Equilibrium

Answer 4

The point in a reversible reaction at which the forward and backward rates of reactions are the same. Therefore, the amounts of substances present in the reacting mixture remain constant

Question 5

Hydrated

Answer 5

Describes a substance that contains water in its crystals

Question 6

Le Châtelier’s principle

Answer 6

When a change in conditions is introduced to a system at equilibrium, the position of equilibrium shifts so as to cancel out the change

Question 7

Precise/precision

Answer 7

A precise measurement is one in which there is very little spread about the mean value. Precision depends only on the extent of random errors-it gives no indication of how close results are to the true (accurate) value

Question 8

Reversible reaction

Answer 8

A reaction in which the products can re-form the reactants

Question 9

Reaction rate

Answer 9

Measure how quickly reactants in a reaction change into the products of a reaction

Question 10

How to measure reaction rate

Answer 10

How quickly reactants decrease, how quickly products increase

Question 11

Main factors that affect reaction rate

Answer 11

Concentration, pressure, temperature and surface area

Question 12

Pressure

Answer 12

Only affects reaction rate if it is a gas as pressure increases->volume decreases->increase in concentration and therefore increase rate of reaction

Question 13

Concentration can mean

Answer 13

More particles in the sane volume or the same amount of particles in a lower volume

Question 14

Measure the rate where a gas is produced

Answer 14

The apparatus needed depends on the nature of the product being measured:
The mass of a substance-solid,liquid or gas-is measured with a balance
The volume of a gas is usually measured with a gas syringe, or sometimes an upside-down cylinder or burette

Question 15

Rates from gradients

Answer 15

The rate of reaction can be calculated from the gradient of a graph of amount of product against time of reaction.

1. Draw a tangent to the curve (a straight line that represents the gradient at that point)
2. Draw a vertical line and horizontal line to form a right- angled triangle with the line from step 1
3. Read off the change in amount of product (the vertical line in your triangle)
4. Read off the change in time (the horizontal line in your triangle)
5. Calculate the gradient. This will be the answer from step 3 divided by the answer from step 4.

Question 16

If you change gas pressure

Answer 16

You change the gas concentration

Question 17

Best catalysts are

Answer 17

Transition metals

Question 18

Increasing temperature increases

Answer 18

Rate of reaction because particles get more energy-more energy to overcome barrier. Particles speed also increases and collisions are more frequent with more energy

Question 19

Dynamic equilibrium

Answer 19

Occurs in a reversible reaction when the forward and backward reactions are going at the same rate and can only occur in a closed system

Question 20

Dynamic

Answer 20

Moving

Question 21

Equilibrium

Answer 21

Balance

Question 22

Homogenous reaction

Answer 22

All substances are in the same state

Question 23

Decreasing the activation energy means

Answer 23

That more particles will have sufficient energy to overcome the energy barrier and react

Question 24

Using catalysts means

Answer 24

Less heat is needed so cheaper and safer and avoid amount use of the mass and volume

Question 25

The effect of changing the concentration on the position of equilibrium

Answer 25

Increase concentration of reactant=equilibrium moves to right
Decrease concentration of reactant=equilibrium moves to left
Increase concentration of product=equilibrium moves to left
Decrease concentration of product=equilibrium moves to the right

Question 26

Anhydrous copper sulfate+water->hydrated copper sulfate

(White).

Answer 26

Just this

Question 27

Le chatelier on temperature

Answer 27

If the temperature is decreased, the equilibrium shifts to the exothermic direction(produced some heat)to try to increase the temperature
If the temperature is increased, the equilibrium shifts to the endothermic direction (absorbs added heat) to try to decrease the temperature
The equilibrium has adjusted to the increase in temperature

Question 28

Le chatelier on pressure

Answer 28

If you increase the pressure, the equilibrium will shift to the side with the fewest gas molecules
If you decrease the pressure, the equilibrium will shift to the side with most gas molecules

Question 29

What effect does a catalyst have on equilibrium

Answer 29

Catalyst has no effect on equilibrium
It only increases the rate of the forward and backward reaction equally
Doesn’t shift position of equilibrium
Reaches equilibrium quicker
Green chemistry-reaction can be carried out at lower temperatures and pressures, saving energy and thereby reducing carbon footprint