Topic 6 (The Rate And Extent Of Chemical Change)

Question 1

What is the rate of a reaction

Answer 1

How fast the products are turned into reactants

Question 2

What graph shows rate of reaction

Answer 2

Amount of product form/Time

Question 3

What is the collision theory

Answer 3

The rate of chemical reactions depends on:
•The collision frequency of reacting particles
•The energy transferred during the collision (Are they successful)

Question 4

What does rate of reaction depend on

Answer 4

•Temperature
•Concentration
•Surface area
•Catalyst

Question 5

To increase the rate of reaction what would you do to the temperature

Answer 5

Increase the temperature, increasing the temperature means particles move faster, the faster they move the more frequent successful collisions they have

Question 6

To increase the rate of reaction what would you do to the concentration

Answer 6

Increase concentration, increasing concentration means more particles over the same volume. This means that there will be more frequent successful collisions

Question 7

To increase the rate of reaction what would you do to the surface area

Answer 7

Increase the surface area,increasing the surface area e.g breaking up one reactant into smaller chunks, means for the same volume the particles will have more area to collide with, therefore more frequent successful collisions

Question 8

To increase the rate of reaction what would you do with a catalyst

Answer 8

Use a catalyst, this decreases the activation energy for the reaction to take place. This means less successful collisions need to take place

Question 9

What is the formula for rate of reaction

Answer 9

Rate=
Reactant used or Product formed/
Time

Question 10

How can you measure a reactions rate

Answer 10

•Precipitation and colour change
•Change in mass
•Volume of gas given off

Question 11

How do you find rate of reaction by measuring volume of gas given off

Answer 11

Reactants in conical flask, attach a gas syringe. Use a timer and then take readings of the volume of gas in the gas syringe at regular intervals.

Question 12

How do you find rate of reaction with colour change and precipitation

Answer 12

Sodium Thiosulfate and HCL form a yellow precipitate. Place a conical flask over a large X. Put the reactants in the conical flask and time how long it takes for the X to disappear as the solution becomes cloudy

Question 13

What is a reversible reaction

Answer 13

A reaction where the products can react to form the reactants again

Question 14

When a reversible reaction reaches equilibrium what does this mean

Answer 14

Products are being produced at the same rate as reactants

Question 15

What is LeChatelier’s Principle

Answer 15

The idea that if you change conditions of a reversible reaction at equilibrium, the system will try to counteract the change

Question 16

In a reversible reaction is the reaction exothermic or endothermic

Answer 16

Both, either the forward reaction or backward reaction will be exothermic and the other will be endothermic

Question 17

What effect does changing temperature have on equilibrium

Answer 17

If you decrease the temperature, the equilibrium will move towards the exothermic direction to produce more heat and counteract the temperature change. If you increase the temperature the opposite effect takes place

Question 18

What effect does changing pressure have on equilibrium

Answer 18

It only changes equilibrium in gases
If you increase the pressure, the equilibrium tries to reduce it, it moves in the direction where there are fewer molecules of gas. If you decrease the pressure the opposite effect takes place

Question 19

What effect does changing concentration have on equilibrium

Answer 19

If you increase concentration of products, it moves towards the reactants and vice versa