rates of reactions and seperating mixtures

Question 1

What are the characteristics of solids?

Answer 1

Particles in contact, attractions hold them together, have definite shape and volume.

Question 2

What are the characteristics of liquids?

Answer 2

Particles in contact but can move around, have a definite volume, take the shape of a container.

Question 3

What are the characteristics of gases?

Answer 3

Particles widely separated, little or no attraction, move freely until they collide, spread out and mix completely, are compressible.

Question 4

Define sublimation.

Answer 4

The process where a solid changes directly into a gas without becoming a liquid.

Question 5

What is melting?

Answer 5

The change of state from solid to liquid at a fixed temperature (melting point).

Question 6

What is evaporation?

Answer 6

The change of state from liquid to gas at any temperature.

Question 7

What is boiling?

Answer 7

The change of state from liquid to gas at a fixed temperature (boiling point).

Question 8

What is freezing?

Answer 8

The change of state from liquid to solid at a fixed temperature (melting point).

Question 9

What is condensation?

Answer 9

The change of state from gas to liquid at a fixed temperature (condensation point).

Question 10

What happens to energy during the change from solid to liquid?

Answer 10

Heat is taken in to break bonds between the particles.

Question 11

What happens to energy during the change from liquid to gas?

Answer 11

Heat is taken in to break the forces between the particles in the liquid.

Question 12

What happens to energy during the change from liquid to solid?

Answer 12

Heat is given out as particles bond together.

Question 13

What happens to energy during the change from gas to liquid?

Answer 13

Heat is given out as particles bond together.

Question 14

What does kinetic theory state about matter?

Answer 14

Matter is made of tiny particles that move all the time.

Question 15

What are the main points of kinetic theory?

Answer 15

• All matter is made of tiny, invisible, moving particles.
• The particles move all the time. The higher the temperature, the faster they move.
• Heavier particles move more slowly than light ones at a given temperature.

Question 16

What is diffusion?

Answer 16

The mixing of atoms or molecules due to their continuous and random motion.

Question 17

Provide an example of diffusion.

Answer 17

Mixing of bromine vapour and air.

Question 18

What is Brownian motion?

Answer 18

The constant random movement of tiny particles caused by collision with air or water molecules.

Question 19

What causes Brownian motion?

Answer 19

Collision with invisible air or water molecules, which are themselves in continuous and random motion.

Question 20

What is an example of an experiment demonstrating Brownian motion?

Answer 20

Experiments using gases diffusing in a tube.

Question 21

In the Brownian motion experiment, what forms when ammonia and hydrochloric acid particles meet?

Answer 21

White smoke (ammonium chloride) forms.

Question 22

Fill in the blank: The higher the temperature, the _______.

Answer 22

faster the particles move.

Question 23

True or False: Heavier particles move faster than lighter ones at a given temperature.

Answer 23

False.

Question 24

What theory explains changes in state when substances are heated or cooled?

Answer 24

Kinetic theory

Kinetic theory describes the motion of particles in different states of matter.

Question 25

In a solid, how are the particles held in position?

Answer 25

By bonding to their neighbours ## Footnote This bonding restricts the movement of particles in solids.

Question 26

What happens to particles in a solid when it is warmed?

Answer 26

They vibrate but cannot move ## Footnote This vibration increases with temperature but does not lead to a change in state yet.

Question 27

What occurs when a solid is heated enough to melt?

Answer 27

Particles vibrate so much that they can tear themselves free from their positions ## Footnote This transition from solid to liquid is known as melting.

Question 28

What needs to be added at the melting point to melt a solid?

Answer 28

Heat energy ## Footnote This energy breaks the bonds between the particles, resulting in a temperature plateau during melting.

Question 29

What happens to the temperature of a substance during melting?

Answer 29

It does not rise until it is all liquid ## Footnote This is because the added heat energy is used to break bonds, not to increase temperature.

Question 30

As a liquid is heated, what do the particles gain?

Answer 30

Energy ## Footnote This gained energy increases the temperature of the liquid until boiling occurs.

Question 31

What happens at the boiling point?

Answer 31

Heat energy needs to be added to break the forces between the particles in the liquid ## Footnote This process converts the liquid into a gas.

Question 32

Fill in the blank: In a solid, particles are held in position by _______.

Answer 32

bonding to their neighbours ## Footnote This bonding is crucial for maintaining the solid state.

Question 33

Fill in the blank: At the melting point, the temperature does not rise until it is all _______.

Answer 33

liquid ## Footnote This is a key characteristic of phase changes.

Question 34

What is the relationship between raw data and graphs in experiments?

Answer 34

Raw data is used to plot graphs to determine relationships between the investigated variables.

Question 35

How is the rate of a reaction represented in a graph?

Answer 35

The rate of the reaction is shown by the steepness of the curve.

Question 36

What happens to the total amount of product in reactions with the same amounts of reactants?

Answer 36

The total amount of product should be the same in all reactions.

Question 37

What indicates a higher reaction rate in terms of time?

Answer 37

The higher the rate, the shorter the time for a reaction to finish.

Question 38

List the factors that affect the rate of a reaction.

Answer 38

* Temperature * Concentration * Surface area * Pressure of gases * Catalyst

Question 39

What effect does an increase in concentration of a reactant have on the reaction rate?

Answer 39

An increase in concentration leads to an increase in the rate of reaction.

Question 40

How does temperature affect the reaction rate?

Answer 40

An increase in temperature leads to an increase in reaction rate.

Question 41

What is the effect of surface area on the rate of a reaction?

Answer 41

An increase in surface area or smaller particle size speeds up the reaction.

Question 42

What is the effect of pressure on the rate of a reaction involving gases?

Answer 42

An increase in pressure speeds up the reaction.

Question 43

What role does a finely divided catalyst play in a reaction?

Answer 43

It speeds up the reaction by acting as a catalyst and providing greater surface area.

Question 44

What trend is observed in the rate of reaction over time?

Answer 44

The rate of reaction is always highest at the start and decreases as the reaction goes on.

Question 45

Fill in the blank: In any reaction, the concentration of reactants is highest at the start and ______ as the reaction progresses.

Answer 45

decreases

Question 46

True or False: The rate of reaction increases as the amount of reactants decreases.

Answer 46

False

Question 47

What does the particle collision theory state about reactant particles?

Answer 47

Reactant particles must collide successfully to react.

Question 48

What is a successful collision also called?

Answer 48

A reactive collision.

Question 49

What must particles do during a collision for a reaction to occur?

Answer 49

Collide with enough energy to break old bonds and form new bonds.

Question 50

How is the reaction rate defined according to the particle collision theory?

Answer 50

Reaction rate = number of successful/reactive collisions.

Question 51

What effect does an increase in reactant concentration have on the rate of reaction?

Answer 51

It leads to an increase in the rate of reaction.

Question 52

Why does higher concentration increase the rate of reaction?

Answer 52

More reactant particles in the same space increase the likelihood of collisions.

Question 53

How does an increase in surface area affect the reaction rate?

Answer 53

It speeds up the reaction by allowing more particles to collide.

Question 54

What happens to the reaction rate when particle size is smaller?

Answer 54

It increases due to a greater surface area for collisions.

Question 55

What is the effect of increased pressure on the reaction rate?

Answer 55

It speeds up the reaction by bringing particles closer together.

Question 56

Why does increased pressure lead to more reactive collisions?

Answer 56

It reduces the volume of the reactants, resulting in closer particle proximity.

Question 57

What is a compound?