C5/6

Question 1

what does pure mean?

Answer 1

a substance is made up of one substance
- it can be an elemnt or compound

Question 2

what is a compound

Answer 2

made of more than one type of atom bonded together

Question 3

what is an element

Answer 3

substances with only one type of atom

Question 4

how can we distinguish between pure and impure substances

Answer 4

melting and boiling points

Question 5

how do we know if a substance is impure

Answer 5

if it melts over a range of temperatures

Question 6

what is a formulation

Answer 6

a mixture that has been designed as a useful product

Question 7

examples of formulations

Answer 7

medicines, paints, washing up liquids, fuels, fertilisers

Question 8

what is a mixture?

Answer 8

groups of atoms, elements and compounds that are mixed but not bonded

Question 9

what is a solute?

Answer 9

solid that can dissolve in a solvent

Question 10

what is a solution?

Answer 10

mixture formed when a solvent dissolves a solute

Question 11

what is a solvent?

Answer 11

substance that dissolves a solute

Question 12

what is filtration used to separate?

Answer 12

an insoluble solid from a liquid

Question 13

what is crystallisation used to separate?

Answer 13

a soluble solid from a solution

Question 14

what is simple distillation used to separate?

Answer 14

separates a solvent from a solution

Question 15

what is fractional distillation used for?

Answer 15

used to separate different liquids from a mixture of liquids

Question 16

how does filtration work?

Answer 16

the insoluble solid is left behind on the filter paper as residue and the liquid passes through the filter paper

Question 17

how does crystallisation work?

Answer 17

liquid evaporates as the solution is heated, leaving behind the solid

Question 18

how does simple distillation work?

Answer 18

• liquid evaporates from the solution, it then cools and condenses in a condenser
• liquid is then collected based on boiling points

Question 19

how does fractional distillation work?

Answer 19

1. heat the mixture so it boils at the bottom to form vapours
2. vapour rises at column
3. the column is hot at the top and cool at the bottom
4. vapours condense at different temperatures, depending on their boiling points

Question 20

what is the atomic mass made up of?

Answer 20

protons and neutrons

Question 21

what is relative formula mass?

Answer 21

adding up all of the relative atomic masses in the compound

Question 22

how is relative formula mass presented

Answer 22

Mr

Question 23

what is the conservation of mass?

Answer 23

no atoms are lost or made in a chemical reaction

Question 24

what is avogadro’s number?

Answer 24

6.02 x 10(23)

Question 25

how do you work out mass?

Answer 25

moles x Mr

Question 26

how do you work out moles?

Answer 26

mass/Mr

Question 27

how do you work out Mr?

Answer 27

mass/moles

Question 28

what is a solvent

Answer 28

liquid that the solute dissolves in

Question 29

what is the mobile phase

Answer 29

phase in chromatography that moves, usually a solvent or a mixture of solvents

Question 30

stationary phase

Answer 30

phase in chromatography that does not move, for example the paper

Question 31

why must the start line be in pencil

Answer 31

pen is an ink and could affect the results and pencil is insoluble

Question 32

what is Rf

Answer 32

distance moved by substance/distance moved by solvent

Question 33

what does a larger Rf mean

Answer 33

the solute is more soluble

Question 34

what is a chemical reaction?

Answer 34

change that involves rearranging atoms within reactant molecules and the formation of a new product

Question 35

how can we tell a chemical reaction has taken place

Answer 35

- colour change - temperature change - bubbles - precipitate formation - odours and sounds

Question 36

what is the rate of reaction

Answer 36

the speed at which a reaction occurs

Question 37

examples of reactions

Answer 37

- rusting - baking - explosions

Question 38

how can you measure the rate of reaction

Answer 38

change in mass, volume, colour or time taken to tur cloudy or precipitate formation

Question 39

rate of reaction equation

Answer 39

quantity of reactant used or product formed/time taken

Question 40

for a chemical reaction to happen... (collision theory)

Answer 40

* reactant particles must collide with each other * particles must have enough energy to react

Question 41

whats a successful collision

Answer 41

a collision that produces a reaction

Question 42

what is activation energy

Answer 42

minimum amount of energy needed to start a reaction

Question 43

what happens if a particle doesnt have enough energy

Answer 43

they just bounce off each other

Question 44

what factors affect rate of reaction

Answer 44

concentration, temperature, catalysts, surface area, pressure

Question 45

how does temp affect ror

Answer 45

as temp increases, the particles move faster so collide more frequently

Question 46

how does catalysts affect ror

Answer 46

they lower activation energy by providing alternate reaction pathways so increases successful collisions

Question 47

how does SA affect ror

Answer 47

increased collision frequency as theres more contact points in the surface of particles

Question 48

how does pressure/concentration affect ror

Answer 48

theres more particles/unit volume making collisions more frequent

Question 49

what does concentration measure

Answer 49

solutions

Question 50

what does pressure measure

Answer 50

gases

Question 51

what is a catalyst

Answer 51

* substance that speeds up reaction without being used up in the reaction * they provide alternate pathway for reaction

Question 52

examples of catalysts

Answer 52

nickel, iron, platinum

Question 53

advantages of using catalysts

Answer 53

* products can be made more quickly so save enrgy and money * expensive byt reuseable * reduce the need to increase temperature so save fuel and pollution

Question 54

biological catalysts

Answer 54

* enzymes - work best in a naerrow range of temp and pH * used in everyday products like washing powders, breaking down food stains

Question 55

biological catalysts

Answer 55

* enzymes - work best in a narrow range of temp and pH * used in everyday products like washing powders, breaking down food stains