C6 - The Rate and Extent of Chemical Change

Define activation energy

The minimum amount of energy that particles must have to react

mean rate of reaction =

quantity of product formed / time taken OR quantity of reactant used / time taken

What are the four factors affecting rate of reaction?

Temperature,

Concentration/pressure,

Surface area,

Catalyst

Do transition metals make good catalysts?

Yes

What two things can we measure to find the rate of reaction?

How fast the reactants are used up

How fast the products are formed

What two equations can be used to calculate the rate of reaction?

quantity of reactant used/time taken

quantity of products formed/time taken

What would the graph have on its y axis if it started from the bottom?

Products produced

What is collision theory?

In order for particles to react, they have to collide with sufficient energy known as the activation energy

What happens if particles collide with less energy than the activation energy?

Nothing

What two things affect the rate of reaction?

Frequency of collisions,

Amount of energy the particles have

What does concentration usually refer to?

Solutions or liquids

What does pressure usually refer to?

Gases

What does a catalyst do to increase the rate of reaction?

Finds a reaction pathway with a lower activation energy

What are the four methods to measure rate of reaction?

Gas Syringe,

Loss of mass,

Water displacement,

Disappearing cross

What is the relationship between the amount of gas produced and the amount of limiting reactant?

directly proportional

At equilibrium, if the concentration of reactants is higher than the concentration of products, we say that the position of equilibrium lies to the:

left

If the position of equilibrium lies to the right, it means there are more:

products

In a reversible reaction, if the forward reaction is endothermic, what would be the effect of increasing the temperature?

Equilibrium shifts to the right

Define dynamic equilibrium

When the rate of the forward reaction is equal to the rate of the backward reaction so the concentrations remain constant

What is the key condition for a reaction to reach dynamic equilibrium?

Takes place in a closed system

What is the catalyst used in the process that makes ammonia?

iron

What is le Chatelier's principle?

If a condition in a reversible reaction is changed, the position of equilibrium will shift to try and counteract that change

At equilibrium, if there are more products than reactants, we say that the position of equilibrium lies:

to the right

In a reversible reaction, changes in pressure will only affect substances that are in the:

gaseous state

Name some possible units for rate of reaction

g/s

g/min

cm^3s^-1

What is a reproducible measurement?

A measurement that can be repeated by a different person or with different techniques or equipment that still gets the same result.

How can you test for carbon dioxide?

Limewater goes milky

What effect on the equilibrium position is produced by adding a catalyst to a system in equilibrium?

It has no effect

Why does the use of catalysts in industry benefit the environment?

Reduces the burning of fossil fuels

Define reversible reactions

The products of the reaction can react to produce the original reactants under certain conditions