topic 4 chemistry

Question 1

what is it called when metals react with oxygen?

Answer 1

oxidation

Question 2

what is it called when oxygen is removed from a compound?

Answer 2

reduction

Question 3

What is the order of the reactivity series

Answer 3

Potassium,sodium,calcium,magnesium,aluminium,carbon,zinc,iron,tin,lead,hydrogen,copper,silver gold platinum

Question 4

Describe why one metal can displace another?

Answer 4

In summary, one metal can displace another from a compound if it is more reactive. This is due to the activity series of metals, where a more reactive metal will replace a less reactive one in a single displacement reaction, as it has a stronger tendency to lose electrons and form positive ions.

Question 5

What happens with Potassium in oxygen water and dilute acid? (group 1)

Answer 5

oxygen: When cut becomes tarnished and dull very quickly
Water: fizzed and moved quickly on the water surface in a ball shape and produced a liluc flame (producing hydrogen gas)
Acid: reacts vigorously and produces hydrogen gas

Question 6

What happens with Sodium in oxygen water and dilute acid? (group 1)

Answer 6

oxygen: becomes tarnished quite quickly and goes from shiny to dull
water: fizzed and smoked and moved quite fast around the surface of the water (producing hydrogen gas)
Acid: reacts vigorously and produces hydrogen gas

Question 7

What happens with Lithium in oxygen water and dilute acid? (group 1)

Answer 7

oxygen: became tarnished and dull slowly
water:fizzed and bubbled slowly around the waters surface (producing hydrogen gas)
Acid: reacts producing hydrogen gas

Question 8

What happens with Magnesium in oxygen water and dilute acid? (group 2)

Answer 8

Acid: lots of fizzing and small bubbles

Question 9

What happens with Zinc in oxygen water and dilute acid?

Answer 9

acid:small bubbles around the zinc sample

Question 10

What is an ore?

Answer 10

its a rock containing a metal compound, usually a metal oxide but it only referred an ore if it is economically beneficial.

Question 11

Describe the process of smelting

Answer 11

coal is heated to produce a higher carbon content resulting in coke
The ore (containing ion oxide) is heated at very high temperatures in a blast furnace
coke is blasted through the (iron) ore which is turned into carbon monoxide from reacting with the oxygen in the ore because carbon is more reactive
Impurities in the ore combine with limestone added to the furnace to remove impurities
This forms a separate layer of slag, which is less dense than the molten metal and floats on top.
The molten metal, now separated from the slag is cooled into solid form for further use

Question 12

State what the problems with copper ores are?

Answer 12

Environmental Concerns: Mining copper ores can lead to habitat destruction, soil erosion, and water contamination from toxic by-products.

Question 13

Waste Management: The process generates a significant amount of waste rock and slag, which can pose long-term environmental risks.

Question 14

Energy Demands: Extracting copper from lower-grade ores requires more energy, resulting in higher costs and carbon emissions.

Question 15

what is Phytomining?

Answer 15

Phytomining is an environmentally friendly way to extract metals, such as copper, from low-grade ores or contaminated soils by using plants.

Question 16

Describe the process of phytomining?

Answer 16

As the plants grow, their root systems absorb metal compounds from the soil, storing them

Question 17

The plant containing the metal compound is burned and the metal compound (eg copper) reacts with oxide ions from the air.

Question 18

Ash containing the metal oxide(copper oxide) is reacted with sulfuric acid

Question 19

Once filtered a solution (of copper sulfate) is produced

Question 20

Electrolysis is used to separate the sulfate and the metal compound (copper metal collects at the negative electrode)

Question 21

what is bioleaching?

Answer 21

Bioleaching is an environmentally friendly method of extracting metals, such as copper and gold, from low-grade ores using bacteria.

Question 22

Describe the process of bioleaching?

Answer 22

Bioleaching uses certain bacteria to produce a solution called a leachate

Question 23

when bacteria is left with a low grade metal ore it produces leachates which contain a compound of that metal

Question 24

this solution is used in electrolysis to make a pure metal

Question 25

the process is repeated to make it worthwhile as only small amounts are produced

Question 26

What is oxidation in terms of electrons?

Answer 26

loss of electrons

Question 27

What is reduction in terms of electrons?

Answer 27

gaining of electrons

Question 28

What do bases normally end in?

Answer 28

oxide, hydroxide, carbonate

Question 29

What do salts normally end in?

Answer 29

sulfates, nitrates, chloride

Question 30

Describe how a salt is made?

Answer 30

a salt has two parts, the first part comes from the base and its a metal and the second comes from the acid

Question 31

eg acid + alkali/base > salt + water

Question 32

eg acid + carbonates > salt + water + carbon dioxide

Question 33

examples of acids and what type of salts they make

Answer 33

hydrochloric acid >metal chlorides

Question 34

sulfuric acid >metal sulfates

Question 35

nitric acid >metal nitrates

Question 36

describe the process to make dry copper sulfate crystals

Answer 36

sulfuric acid is heated in a beaker and copper oxide is added while stirring to ensure reaction proceeds quickly

Question 37

until the copper oxide is in excess to ensure all acid has reacted

Question 38

then the mixture is filtered by pouring it through a funnel lined with filter paper to remove the excess copper oxide

Question 39

Then the solution heated in an evaporating basin/dish over a boiling water bath to evaporate the water

Question 40

the solution is allowed to crystallize/cool down to allow crystals to form

Question 41

The crystals are removed, rinsed and allowed to dry to purify the product

Question 42

what does a high and low PH have?

Answer 42

a low PH has lots of H+ (hydrogen)

Question 43

a high PH has lots of OH-(hydroxide)

Question 44

Whats needed for neutralization?

Answer 44

All neutralisation reactions involve the hydrogen ions(H+) from the acid reacting with the hydroxide(OH-) from the alkali to form water

Question 45

Whats produced when a weak alkali is added to a strong acid?

Answer 45

A strong acid will contain lots of H+ and if you add a weak alkali it will contain few )OH-. So when the H+ and OH- ions bond there will be H+ ions left over resulting in a weak acid

Question 46

define solute?

Answer 46

a solute particle is the substance being dissolved, it can be a solid liquid or gas.

Question 47

define solvent?

Answer 47

a solvent particle is the liquid the solute is being dissolved in

Question 48

how much solvent and solute are in a concentrated solution?

Answer 48

lots of solute in a small amount of solvent

Question 49

how much solvent and solute are in a dilute solution?

Answer 49

small amount of solute in a large amount of solvent

Question 50

what do acids ionise in?

Answer 50

in a aqueous solution(aq) this means the acid molecules break down (dissociate) to give positive hydrogen ions and negative ions

Question 51

what is a strong acid? and give examples?

Answer 51

strong acids are fully ionised in a aqueous solution eg hydrochloric acid, sulfuric acid

Question 52

what is a weak acid? and give examples?

Answer 52

weak acids are partially ionised in an aqueous solution eg ethanoic acid, citric acid, carbonic acid

Question 53

whats a reversible reaction?

Answer 53

the reactants become the products but the products can also become the reactants, this happens with weak acids

Question 54

how do you describe a weak and strong acid?

Answer 54

the extent of ionisation

Question 55

how do you describe a concentrated and dilute acid?

Answer 55

substance dissolved in a certain volume

Question 56

what is Titration?

Answer 56

Titration is a laboratory technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration.

Question 57

Describe the process of the Titration practical?

Answer 57

Use a pipette and pipette filler to fill it with exactly 25cm 2 of sodium hydroxide. A pipette is used as its very precise

Question 59

When measuring the the sodium hydroxide make sure your looking at the measurements at eye level to avoid parallax error

Question 61

Transfer the solution of the unknown concentration into a conical flask and place the burette just above the flask to avoid splashing

Question 63

close the burette tap to ensure no acid will fall into our alkali before we need it to

Question 65

use a funnel to fill the burette with the solution of the unkown concentration

Question 67

add a few drops of indicator(phenolphthalein) and swirl the solution

Question 69

add the acid drop by drop into the solution whilst swirling to make sure its fully mixed so we can see the reactions

Question 71

stop as soon as the solution changes colour, to make sure it fully reacts

Question 73

record how much solution it took yo change colour so you can calculate the concentration

Question 74

What does electrolysis do?

Answer 74

uses electric current to break down an ionic substance into its elements

Question 76

the electric current flows into the electrolyte via rods called electrodes

Question 77

what is a electrolyte?

Answer 77

the substance being broken down in electrolysis and is a solution that contains an ionic compound

Question 78

what are negatively charged ions called?

Answer 78

anions

Question 79

what are positively charged ions called?

Answer 79

cations

Question 80

Why does the electrolyte have to be a liquid?

Answer 80

so the ions are free to move to the electrodes

Question 81

why is electrolysis so expensive?

Answer 81

uses a lot of energy

Question 82

why are electrodes normally made from graphite?

Answer 82

Because they are good conductors of electricity as it contains lots of delocalised electrons that can then carry energy

Question 83

what electrode do cations go to?

Answer 83

Cathode (negatively charged)

Question 84

what electrode do anions go to?

Answer 84

Anode (positively charged)

Question 85

What happens at the electrodes?

Answer 85

When the charged ions go to the oppositely charged cathode they are loose or gain electrons to become neutral and are discharged

Question 86

why does electrolysis only work with ionic compounds?

Answer 86

because they contain charge and the negative and positive ions can be separated

Question 87

what is oxidation in electrolysis?

Answer 87

loos of electrons

Question 88

what is reduction in electrolysis?

Answer 88

gain of electrons

Question 89

what is the concentration of H+ measured in?

Answer 89

mol/dm^3

Question 90

what does PH 1 measure in decimal form?

Answer 90

10^-1 = 0.1

Question 91

what does PH 3 measure in decimal form?

Answer 91

10^-3 = 0.001

Question 92

what does PH 5 measure in decimal form?

Answer 92

10^-5 = 0.00001

Question 93

what is aluminium ore called?

Answer 93

bauxite

Question 94

why is extraction of aluminium so expensie?

Answer 94

because aluminum has a very high melting point as it has strong bonds, to break these bonds and turn it into a molten state would require a lot of energy which is expensive

Question 95

what's the half equation of aluminum at the cathode?

Answer 95

Al 3+ +3e- > Al

Question 96

what's the half equation of aluminum at the anode?

Answer 96

20 2- >4e- + 02

Question 97

why is aluminium oxide dissolved in molten cryolite?

Answer 97

because it has a much lower melting point which reduces the energy cost

Question 98

Why do the carbon anodes (when extracting aluminium) have to regularly replaced adding to the cost of the extraction?

Answer 98

Because the carbon anodes are worn away when C02 from the anode reacts with the oxygen from the solution

Question 99

what ions does water form?

Answer 99

H20 >(reversible reaction) H+ + OH-

Question 100

What is the rule for electrolysis for what happens at the cathode(negative electrode)?

Answer 100

hydrogen is produced if the metal is more reactive than hydrogen. Otherwise the metal is produced

Question 101

What is the rule for electrolysis for what happens at the cathode(positive electrode)?

Answer 101

oxygen is produced unless the solution contains a halogen (group 7) ions. Otherwise the halogen is produced