principles of chemistry

Question 1

what are the properties of solids

Answer 1

fixed shape and volume
cannot be compressed

Question 2

what are the properties of liquids

Answer 2

no fixed shape, but take the shape of their container
fixed volume
can flow
cannot be compressed

Question 3

what are the properties of gas

Answer 3

no fixed shape, but take the shape of their container
do not have a fixed volume, but take up the volume of their container
can flow
can be compressed

Question 4

properties of solids in terms of particles

Answer 4

have a regular arrangement
are tightly packed, particles are touching each other
vibrate about their position
have strong forces of attraction holding them in position

Question 5

properties of liquids in terms of particles

Answer 5

have no regular arrangement
are tightly packed, particles are touching each other
move randomly at different speeds
do not move far as they frequently collide with other particles
have weaker forces of attraction compared to solids

Question 6

properties of gas in terms of particles

Answer 6

have no regular arrangement
move randomly at different speeds, but much faster than liquids
have very weak forces of attraction compared to solids

Question 7

what is melting

Answer 7

Applying thermal energy to a solid substance will result in it eventually becoming a liquid

Question 8

what is evaporation

Answer 8

when liquid turns into gas

Question 9

what is boiling

Answer 9

The process of applying thermal energy to a liquid to obtain a gas is called

Question 10

what is condensation

Answer 10

turning gas into liquid, by cooling a gas

Question 11

what is freezing

Answer 11

turning liquid into solid by further cooling the liquid

Question 12

what is sublimation

Answer 12

from solid to gas

Question 13

state change in state in terms of kinetic theory

Answer 13

the kinetic energy of the particles determines which state of matter a substance exists in. As the temperature of a substance increases, the average kinetic energy of the particles is increased and this can affect the physical state and properties of the material.

Question 14

relationship between temp and gas state

Answer 14

As heat is added to the gas, the temperature of the gas increases. This makes each particle move faster and further, but still in random directions. It increases the distance between the particles, so the volume the gas occupies increases as the temperature increases.

Question 15

relationship between pressure and gas state

Answer 15

In a gas, the particles exert a pressure on the walls (or sides) of any container in which they are held
When you increase the pressure of a gas at a fixed temperature, the volume of the gas decreases

Question 16

describe and explain diffusion

Answer 16

diffusion is the movement of the particles from the area of high concentration to the area of lower concentration. We describe this as moving down the concentration gradient

Question 17

describe and explain dependence of rate of diffusion on molecular mass

Answer 17

The greater the mass of the molecules, the slower the molecules move at any given temperature. At any given temperature, all substances have the same average kinetic energy. Therefore, lighter molecules need to have a greater velocity than heavier molecules.

Question 18

describe difference between elements mixtures and compounds

Answer 18

element- made of only one type of atom, cannot be further broken down

compound-elements within cannot be further seperated, made when two or more elements chemically bond in a reaction

mixtures-made when elements or compounds are mixed with each other, substances within are not chemically bonded together, can be easily seperated

Question 19

describe properties of metals

Answer 19

good conducters of electricity and heat, usually high melting point, malleable, ductile

Question 20

describe properties of non-metals

Answer 20

bad conducters of electricity and heat, usually low melting point, not malleable,brittle

Question 21

what is used to measure time

Answer 21

stopwatch

Question 22

what is used to measure temp

Answer 22

thermometer

Question 23

what is used to measure mass

Answer 23

mass balance

Question 24

what is used to measure volume

Answer 24

burettes, volumetric pipettes, measuring cylinders and gas syringes

Question 25

what are the methods of purification

Answer 25

with a solvent, filtration, crystsllisation, distillation

Question 26

explain method of purification with a solvent

Answer 26

to separate two solids this method can be used, firstly add the solvent to the mixture, one solid must be soluble and the other not, then remove the not soluble solid from solvent, and evaporate solvent from remaining solid.

Question 28

explain method of purification via filtration

Answer 28

used to separate an insoluble solid from a liquid, requires a filter funnel, the solid isnt able to pass through holes in filter paper, and is none as the residue, the liquid that can pass through is known as the filtrate

Question 29

explain method of purification via crystallisation

Answer 29

to separate a soluble solid from a liquid, which have a different solubility. As temp of solution decreases less space available for solid in liquid, particles pushed out and gradually become crystals

Question 30

explain method of purification distillation

Answer 30

separation of two liquids. through temporarily transforming them into gases.
first solution is heated in a distillation flask, then liquid with lowest boiling point evaporates and becomes a gas, it passes along the condenser in which cold water is passing through, which cools gas back into a liquid, which is collected in a beaker

Question 31

explain method of purification fractional distillation

Answer 31

used to separate multiple liquids with different boiling points approximatly 25 c proximity. Apparatus same as simple distillation but has a frwctionating column, which has beads to provide a cool surface in which the vapour of liquid with highest boiling point go through and will condense and drop back into flask.

Question 32

what is a solvent

Answer 32

a substance that dissolves a solute eg water

Question 33

what is a solute

Answer 33

a substance that is dissolved in a solvent eg sugar

Question 34

what is a solution

Answer 34

a mixture of one or more solutes dissolved in a solvent

Question 35

what is a saturated solution

Answer 35

a solution containing max concentration of a solute dissolved in the solvent at a specific temperature

Question 36

what is a residue

Answer 36

substance that remains after evaporation, distillation, filtration or any similiar process

Question 37

what is a filtrate

Answer 37

a liquid or solution that has passed through a filter

Question 38

what is the boiling and freezing point of water

Answer 38

100 degrees and 0

Question 39

in chromotography how do you know substance is pure

Answer 39

only one spot/ colour is seen after process is done

Question 40

in chromotography how can you tell a bit of the solute composition

Answer 40

if you also tested other substances, and the seperation has the same distance travelled in one spot, they contain the same solute

Question 41

how is chromotography used to separate mixtures of soluble coloured substances

Answer 41

the unknown substances (solutes) are carried up a sheet of filter paper by the solvent, solutes move at different rate according to their mass and solubility, therefore they are deposited at differnet places in filter paper, being able to distinguish the solutes that compose the solution. A locating agent may also be used, which is a chemical substance that reacts with the seperated solutes to produce a coloured substance, clearly visible to calculate the rf value

Question 42

what is rf value

Answer 42

distance travelled by the solute/ distance travelled by the solvent