States Of Matter And Mixtures

Question 1

What are the 3 states of matter?

Answer 1

Solid
Liquid
Gas

Question 2

What is the kinetic particle theory of matter?

Answer 2

It is a model that describes the arrangement, movement and energy of particles in a substance. The model is used to explain the physical properties of solids, liquids and gases.

Question 3

What are the common changes of state?

Answer 3

Solid to liquid= melting
Liquid to gas= evaporating
Gas to liquid= condensing
Liquid to solid=solidifying/freezing

Question 4

What is sublimation?

Answer 4

Sublimation is where a substance can change directly from solid to gas or gas to solid.

Question 5

What must be transferred for a substance to change state?

Answer 5

Energy

Question 6

Why do the particles have to gain energy?

Answer 6

The particle has to gain energy to break and overcome:

• some of the bonds between particles during melting
• all the remaining bonds between particles during evaporating or boiling

Question 7

Where must energy transfer to from the substance in order for condensation and freezing to happen?

Answer 7

Energy must be transferred from the substance to the environment. During these changes in state, the particles loose energy as bonds from between particles

Question 8

How can you guess the state of a substance at a given temperature?

Answer 8

If it’s melting point and boiling point are known.

Question 9

What is a pure substance?

Answer 9

A pure substance consists only of one element or compound.

Question 10

What is a mixture?

Answer 10

A mixture consists of 2 or more different substances not chemically joined together.

Question 11

What are the different types of chemical substance?

Answer 11

• an element contains just one type of atom
• a compound contains 2 or more types of atom joined together
• a mixture contains 2 or more substances that are not joined together
• the different substances in a mixture can be elements or compounds

Question 12

Do pure substances have a sharp melting point or do they melt over a range of temperatures?

Answer 12

Pure substances have a sharp melting point but mixtures melt over a range of temperatures.

Question 13

What is filtration?

Answer 13

Filtration is used to separate an insoluble solid from a liquid. It is useful for separating sand from a mixture of salt and water, or excess reactant from a solution.

Question 14

What is crystallisation?

Answer 14

Crystallisation is used to produce solid crystals from a solution. When the solution is warmed,some of the solvent evaporates leaving behind a more concentrated solution.

Question 15

What is simple distillation?

Answer 15

Simple distillation is used to separate a solvent from a solution. It is useful for producing water from salt solution.

Question 16

Why does simple distillation work?

Answer 16

It works because the dissolved solute has a much higher boiling point than the solvent. When the water is heated, solvent vapour evaporates from the solution. The gas moves away and is cooled and condensed. The remaining solution becomes more concentrated in the solute as the solvent in it decreases.

Question 17

What is fractional distillation?

Answer 17

Fractional distillation is used to separate different liquids from a mixture of liquids.

Question 18

How does fractional distillation work?

Answer 18

• vapours rise through a column which is hot at the bottom and cold at the top
• vapours condense when they reach a part of the column that is below the temperatures of their boiling point
• the liquid flows out the column
• the substance with the lowest boiling point is collected at the top of the column.

Question 19

What is paper chromatography?

Answer 19

Paper chromatography is used to separate mixtures of soluble substances.

Question 20

What 2 phases does paper chromatography rely on?

Answer 20

• the stationary phase, which in paper chromatography is very uniform, absorbent paper
• the mobile phase is the solvent that moves through the paper,carrying different substances with it

Question 21

How many spots does a pure substance produce in paper chromatography?

Answer 21

A pure substance produces one spot

Question 22

How many spots does an impure substance produce?

Answer 22

An impure substance produces two or more spots

Question 23

How do you know if 2 substances are the same in paper chromatography?

Answer 23

They produce the same number of spots and these match in colour
The spots travel the same distance up the paper (they have the same Rf value)

Question 24

How do you calculate the Rf value?

Answer 24

Distance traveled by substance
Rf=—————————————-
Distance travelled by solvent

Question 25

What is Rf value?

Answer 25

Rf values can be used to identify unknown chemicals if they can be compared to a range of reference substances. The Rf is always the same for a particular substance.

Question 26

What does fresh water contain that has to be removed to make it drinkable?

Answer 26

Large objects such as leaves or branches
Insoluble particles such as grit
Harmful microorganisms

Question 27

How are large objects removed when making fresh water drink able?

Answer 27

Large objects are removed by screening using grids

Question 28

How are insoluble particles removed from fresh water?

Answer 28

A coarse filter bed made from clean sand and gravel removes larger insoluble grit particles. Aluminium sulfate is added to clump smaller insoluble particles together, which settle to the bottom in a sedimentation tank. A fine filter bed removes very small insoluble particles.

Question 29

How do you get rid of harmful microorganisms in fresh water?

Answer 29

Chlorine gas is added to kill harmful microorganisms.