C5-Chemical Changes

Question 1

what are most metals

Answer 1

Most metals ores (rocks that contain metal)
Most metals in ores are chemically bonded to other elements - mostly oxygen to form metal oxides

Question 2

how would we extract metal from a metal ore

Answer 2

To extract a metal from a metal ore, the ore needs to be reduced (reduced = have the oxygen removed)

Extracting a metal from its ore depends on the metal’s reactivity (as we use displacement reactions)

We use Carbon to displace metals, to produce the metal by itself and carbon dioxide (as the carbon reacts with the oxygen)

Question 3

how do displacement reactions work

Answer 3

Displacement reaction only works when the metal is less reactive than the carbon

Question 4

how would we extract metal more reactive than carbon

Answer 4

For the metals more reactive than carbon, we use electrolysis to extract the metal ore

Question 4

what does oil rig stand for?

Answer 4

OILRIG
Oxidation Is Loss (of electrons)
Reduction is Gain (of electrons)

Oxidation = Gain of oxygen
Reduction = Loss of oxygen

Question 5

what is the pneumonic for the reactivity series

Answer 5

Please Stop Calling Me A Cute Zebra I Like Her Cool Smart Goat

Question 6

how do u check once you have written the half equations

Answer 6

Once you have written a half equation, you need to check that on both sides:
The atoms are balanced
The charges are balanced
Included all state symbols

Question 7

wat does the worth of extracting metals depend on

Answer 7

The worth of extracting a metal depends on:
How easy it is to extract the metal from its ore
How much metal the ore contains
The changing demands for a particular metal

Question 8

what metals are found in their natural state?

Answer 8

A few metals like silver and gold are so unreactive that they are found in their native states

Question 9

what forms when u react carbon with tungsten

Answer 9

Hydrogen is used to reduce Tungsten (W), as if you react Carbon with Tungsten (eventhough carbon is cheaper), it will form Tungsten Carbide

Question 10

how are metals more reactive than carbon extracted

Answer 10

Metals more reactive than carbon are extracted using electrolysis of the molten metal compounds

Question 11

what does Acid+alkali/base produce

Answer 11

acid + alkali/base ⟶ salt + water

Question 11

what does metal oxide + acid make

Answer 11

metal oxide + acid ⟶ salt + water

Question 11

what does metal + acid make

Answer 11

metal + acid ⟶ salt + hydrogen

Question 12

what does metal hydroxide + acid make

Answer 12

metal hydroxide + acid ⟶ salt + water

Question 13

what does metal carbonate+ acid make

Answer 13

metal carbonate + acid ⟶ salt + CO2 + water

Question 14

what does ammonia solution + acid make

Answer 14

ammonia solution + acid ⟶ ammonium salt + water

Question 15

what is a base

Answer 15

A base is anything that neutralises an acid
All alkalis are bases but not all bases are alkalis (as not all bases are soluble)

Question 16

what is an alkali

Answer 16

An alkali is a soluble base
All alkalis are bases but not all bases are alkalis (as not all bases are soluble)

Question 17

Hydrochloric acid formula

Answer 17

Hydrochloric acid = HCl

Question 18

Sulfuric Acid formula

Answer 18

Sulfuric Acid = H2SO4

Question 19

Sulfuric Acid formula

Answer 19

Sulfuric Acid = H2SO4

Question 20

Nitric acid formula

Answer 20

Nitric acid = HNO3

Question 21

Phosphoric Acid formula

Answer 21

Phosphoric Acid = H3PO4

Question 22

Ammonium Ion formula

Answer 22

Ammonium Ion = NH4 1+

Question 23

what does hydroxide mean

Answer 23

it means it is an alkali

Question 24

MAKE SURE TO DO DROP AND SWAP METHOD FOR FINDING FORMULA

Answer 24

MAKE SURE TO DO DROP AND SWAP METHOD FOR FINDING FORMULA

Question 25

what are examples of indicators

Answer 25

Some examples of indicators are: Litmus paper - a strip of paper that turns red for acids and blue for alkalis. This paper turns white/bleaches if you put it in chlorine gas 2. Universal indicator - add drops to your substance and it will change colour ⟶ compare the colour to a pH scale to deduce the exact pH 3. Red Cabbage Indicator - obtained by boiling red cabbage

Question 26

what do acids release when in solution

Answer 26

Acids release protons (which are H+ ions) when in solution

Question 27

what do alkalis release when in solution

Answer 27

Alkalis release hydroxide ions (OH-) when in solution

Question 28

how can we see acids properties

Answer 28

Acids must be dissolved in water to show their acidic properties ⟶ in water, acids ionise/dissociate (meaning split up) into H+ ions on one side, and their negative ions on the other

Question 29

what are strong acids

Answer 29

Strong acids ionise/dissociate completely

Question 30

what are weak acids

Answer 30

Weak acids do not ionise/dissociate completely

Question 31

what are examples of strong acids

Answer 31

Examples of strong acids: 1. HCl 2. H2SO4 3. HNO3 4. H3PO4

Question 32

what are examples of weak acids

Answer 32

ethanoic acid (vinegar) citric acids (citrus fruits) carbonoic acids (rainwater, fizzy drinks)

Question 33

what happens when you decrease concentration by x10

Answer 33

When you reduce the concentration by x10, the pH increases by one unit

Question 34

what happens when you increase concentration by x10

Answer 34

As the concentration of H+ ions increases by a factor of 10, the pH value decreases by one unit

Question 35

what does electrolysis mean

Answer 35

Electro = electricity Lysis = splitting

Question 36

Why does the ionic compound HAVE to be in liquid form for electrolysis

Answer 36

An ionic compound’s natural solid form is a giant ionic lattice - strong ionic bonds keep the ions locked in their place, so they can’t move, so they cannot flow and go to the electrodes

Question 37

what are the 2 states of our electrolyte

Answer 37

As our electrolyte HAS to be liquid, it can be two states ⟶ molten (l) or aqueous (aq)

Question 38

what does molten mean

Answer 38

Molten = the compound is MELTED down into its LIQUID form

Question 39

what does aqueous mean

Answer 39

Aqueous means the ionic compound has been DISSOLVED in WATER (aqua--> water)

Question 40

why is electrodes made out of graphite

Answer 40

there are electrodes which are made out of graphite It needs to be made out of graphite as it a) it can conduct electricity and b) It is inert (unreactive)

Question 41

why does the electrode need to be unreactive

Answer 41

Our electrodes need to be unreactive so that they don’t react with the electrolyte or the products of electrolysis

Question 42

what are cations

Answer 42

Positively charged ions = cations (see the t as a plus sign)

Question 43

what are anions

Answer 43

Negatively charged ions = anions (A Negatively charged ION)

Question 44

what are cations attracted to

Answer 44

CAThodes attract CATions ⟶ so cathodes are negatively charged electrodes

Question 45

what are anions attracted to

Answer 45

ANodes attract Anions ⟶ so anodes are positively charged electrodes

Question 46

what happens to ions at the electrode

Answer 46

At the electrodes, the ions becomes discharged At the electrodes, ions lose their charge and become elements (so this means that at the electrodes, gases are given off, or metals are deposited)