C 5.1-5.8 chemical changes

Question 1

what is the reactivity series

Answer 1

a list of metals in order of their reactivity

Question 2

how can you order metals

Answer 2

by comparing how they react with water or whit dilute acid

Question 3

reaction with water of metals + order of reactivity

Answer 3

alkali metals react giving off hydrogen gas and leaving alkaline solutions, most metals don’t react
potassium
sodium
lithium

Question 4

when do you use acids to show reactivity series

Answer 4

when reaction with water is too slow

Question 5

how do we compare the reactivity of metals

Answer 5

by looking at how fast or violent their reaction with water and acids are

Question 6

the speed of reaction with dilute acids is indicated by…,

Answer 6

rate at which bubbles of hydrogen are given off

Question 7

when does a displacement reaction occur

Answer 7

when a more reactive element displaces a less reactive element from a compound

Question 8

eg of displacemnt reaction

Answer 8

Mg + CuSO4=MGSO4+ Cu

Question 9

what is an ionic equation (eg with Mg + CuSO4=MGSO4+ Cu)

Answer 9

shows only atom and ion that change in a reaction
Mg + Cu(2+)= mg (2+) + Cu

Question 10

how can you give positions in the reactivity series to the non-metals hydrogen and carbon

Answer 10

on the basis of displacement reactions.
carbon can displace zinc from its oxide but not alumionium so in the series is placed in between them two.
copper can’t displace H from an acid whereas lead can so H is in between them

Question 11

most of metals need to be

Answer 11

extracted from a compound

Question 12

what do metals often need to be extracted from

Answer 12

oxides are the ores ,

created from reaction with oxygen

Question 13

name of reaction that separates a metal from its oxide

Answer 13

reduction reaction

Question 14

how does reactivity series help you in ores extraction

Answer 14

help you decide best way to extract the metal

Question 15

what will carbon(non-metal) do to extract metals

Answer 15

will displace less reactive metals from their oxides

can only be used when carbon is more reactive

Question 16

process and equation to extract metals with carbon

Answer 16

heat metal oxide with carbon, removing the hydrogen

metal oxide + carbon = metal + carbon dioxide

Question 17

when is electrolysis used

Answer 17

to extract metals more reactive than metals

Question 18

how and from what is aluminum extracted from compound (aluminum oxide)

Answer 18

electrolysis from bauxite

Question 19

process of electrolysis with aluminum

Answer 19

aluminum oxide is mixed with molten cryolite to lower the very high melting point and reducing the energy needed.
molten mixture contains free ions(conducts energy)
positive ions of AL(3+) are attracted to the negative electrode where they each pick up 3 electrons and turn into neutral atoms.
negative O(-2) ions are attracted to positive electrode where they each lose electrons, forming neutral oxygen that combine to form O2 molecules

Question 20

when is salt formed (metal)

equation

Answer 20

reaction takes place between a metal and an acid, when hydrogen in an acid is wholly or partially replaced by metal or ammonium ions
metal + acid =salt+ hydrogen

Question 21

why are alkali metals never added to acid

Answer 21

too reactive, dangerous

Question 22

what kind of metals can react to form salt

Answer 22

metal must be above hydrogen in reactivity series but not too reactive

Question 23

the salt you make depends on

Answer 23

metal you use

zinc metal will always make zinc salts

Question 24

how can a sample of the salt make from reaction be crystalized

Answer 24

by evaporating off the water

Question 25

what are bases

Answer 25

compounds that can neutralize acids (alaklis)

Question 26

WHAT IS NEUTRALISATION

Answer 26

acid + base = salt + water

Question 27

two reactions where you can make salts

Answer 27

solutions of an acid and an alkali acid with carbonate

Question 28

purpose of indicator

Answer 28

indicate if reaction is acid or alkaline

Question 29

acids react with .... to form salts

Answer 29

metals, bases and carbonates

Question 30

A soluble salt can be prepared by reacting an acid with a suitable insoluble reactant including:

Answer 30

a metal a metal oxide a metal hydroxide a carbonate

Question 31

process to get a soluble salt

Answer 31

Add powdered insoluble reactant to acid in a beaker, one spatula at a time, stirring to mix. Continue adding powder until it is in excess (some unreacted powder is left over). All the acid has now reacted. Filter the mixture in the beaker to remove the excess solid. The filtrate now contains only the salt and water. Heat the solution in an evaporating dish over a water bath. Stop heating when small crystals start to appear around the edge of the evaporating basin. The solution is now saturated. Leave the saturated solution at room temperature for a day or two. This gives time for large crystals to form. If necessary, dry the crystals by dabbing gently with filter paper.

Question 32

what is an acid

Answer 32

substance that forms aqueous solutions with pH less than 7

Question 33

what is a base

Answer 33

substance with pH greater than 7 | metal oxides are bases

Question 34

what do alkalis form in water

Answer 34

OH- ions

Question 35

what do acids do in aqueous solution

Answer 35

they ionise, produce hydrogen ions

Question 36

what happen to strong acids in water

Answer 36

ionise completely , all acids particles dissociate to realese H+ ions

Question 37

what happen to weak acids in solution

Answer 37

do not fully ionise, only a small portion of particles dissociate to release H+ IONS

Question 38

WHAT DOES THE IONISATION OF A weak acid set up

Answer 38

equilibrium between undissociated and dissociated acid, as it is a reversible reaction equilibrium lies to the left as only a few H+ released

Question 39

why are the strong aciuds more reactive on the same concentartion

Answer 39

concentration of H+ higher , rate if reaction faster

Question 40

why is pH of strong acid always less than weak acid in same concentration

Answer 40

for every 1 on pH cale , concentration of H+ ions increase by a factor of 10

Question 41

what is the concentration acids

Answer 41

how much acid in a certain volume of water

Question 42

when will pH decrease(concentartion)

Answer 42

with increasing acid concentration

Question 43

reaction with metal and acid produces | and kind of reactio

Answer 43

hydrogen + salt | redox reaction

Question 44

a carbonate reacts with acid to produce

Answer 44

salt+ water+ carbon dioxide gas