key content to memorise

Question 1

what gases can anhydrous calcium chloride dry?

Answer 1

most gases except ammonia gas

Question 2

what gases can calcium oxide dry?

Answer 2

ammonia gas and all neutral gases

Question 3

what gases can concentrated sulfuric acid dry?

Answer 3

most gases except alkaline gases

Question 4

clue: Mr of air is around 29

what gases are less dense than air?

Answer 4

hydrogen and ammonia

Question 5

what cations form white precipitate in NaOH (aq)?

Answer 5

Ca, Zn, Al & Pb

all are soluble in excess NaOH except Ca

Question 6

what cations form white precipitate in NH3?

Answer 6

Zn, Al & Pb

only Zn is soluble in excess

Question 7

how to differentiate Pb and Al?

Answer 7

add KI. Pb will form yellow ppt but Al will not react

Question 8

what is the test for chloride/iodide ions?

Answer 8

add dilute nitric acid. then add silver nitrate solution

I -> yelllow ppt. Cl -> white ppt

Question 9

what is the test for nitrate ions?

Answer 9

add aqueous sodium hydroxide. then add a piece of aluminium foil and warm the mixture. test the gase evolved using damp red litmus paper

red litmus paper should turn blue

Question 10

what is the test for sulfate ions?

Answer 10

add dilute nitric acid, then add barium nitrate solution

white ppt should form

Question 11

what is the bonding for simple molecular structure?

Answer 11

weak intermolecular forces of attraction

to overcome

Question 12

what is the bonding for giant molecular structure?

Answer 12

strong covalent bonds

to break

Question 13

what is the bonding for ionic compound?

Answer 13

strong electrostatic forces of attraction between oppositely charged ions

to overcome

Question 14

what is the bonding for metallic compound?

Answer 14

strong electrostatic forces of attraction between cations and sea of mobile electrons

to overcome

Question 15

what happens at the anode?

Answer 15

oxidation occurs, electrons are lost

Question 16

what happens at the cathode?

Answer 16

reduction occurs, electrons are gained

Question 17

why does exothermic reaction negative enthalpy change?

Answer 17

energy taken in for bond breaking is less then energy given out in bond forming

exothermic reations; combustion, respiration, neutralisation, corrosion, condensation, freezing

Question 18

why does endothermic reaction have positive enthalpy change?

Answer 18

energy taken in for bond breaking is more than energy given out in bond forming

endothermic reactions: evaporation, decomposition, boiling, melting, photosynthesis

Question 19

what is the colour change when KI is oxidised?

Answer 19

colourless to brown

Question 20

what is the colour change when acidified KMnO4 is reduced?

Answer 20

purple to colourless

Question 21

what oxides are neutral?

Answer 21

nitrogen monoxide, carbon monoxide and water

Question 22

what oxides are amphoteric?

Answer 22

zinc, aluminium and lead

Question 23

SLCB

what sulfates are insoluble?

Answer 23

lead (II), calcium and barium

Question 24

SLC

what chlorides are insoluble?

Answer 24

silver and lead (II)

Question 25

what are the conditions required to make ammonia?

Answer 25

250atm, 450C and iron catalyst

Question 25

# SPA what carbonates are soluble?

Answer 25

group I and ammonium carbonates

Question 26

describe the trend in reactivity, density & melting point down group I

Answer 26

down group I, reactivity increases, density increases and melting point decreases

Question 27

describe the trend in reactivity, colour and melting point down group VII

Answer 27

reactivity decreases, colour gets darker, melting point increases

Question 28

why are alloys harder?

Answer 28

atoms of the added element have a different size from those of the pure metal, disrupting orderly regular arrangement of pure metal atoms. layers of metal atoms cannot slide over each other easily, making the iron alloy harder and less malleable.

Question 29

what metals react with cold water?

Answer 29

potassium, sodium, calcium & magnesium

Question 30

what metals react with steam?

Answer 30

potassium, sodium, calcium, magnesium, zinc, iron ## Footnote doesn't react with aluminium as a layer of aluminium oxide coats the metal

Question 31

what metal oxides can be reduced by carbon?

Answer 31

zinc to silver oxide

Question 32

# High Fat what metal oxides can be reduced by hydrogen?

Answer 32

iron to silver oxide

Question 33

what metal carbonates decompose into metal oxide and carbon dioxide upon heating?

Answer 33

calcium to copper (II) carbonate

Question 34

what metals are extracted by electrolysis?

Answer 34

potassium to aluminium | Zn to Cu extracted by heating the metal compounds with carbon ## Footnote silver is extracted by heating, gold & platinum are found chemically uncombined.

Question 35

how does an increasing percentage of carbon in alloy affect physical properties?

Answer 35

less malleable, less ductile, harder, more brittle

Question 36

what percentage of air is oxygen?

Answer 36

21%

Question 37

what gases are removed by catalytic converter?

Answer 37

carbon monoxide, oxides of nitrogen & unburnt hydrocarbons

Question 38

# Please Pee N Poo Dogs Lions Bears name the fractions in fractionating column during the fractional distillation of crude oil and their uses

Answer 38

petroleum petrol - fuel for cars naphtha - feedstock for chemical industry paraffin - fuel for aircraft engines/cooking diesel - fuel for diesel engines lubricating oil - lubricants bitumen - making road surfaces

Question 39

what are the changes in physical properties of hydrocarbons as size increases?

Answer 39

mp & bp increase viscosity increase flammability decrease

Question 40

what conditions are needed for hydration (addition of steam to alkene)?

Answer 40

phosphoric (V) acid as catalyst, 300C, 60atm

Question 41

what conditions are needed for hydrogenation (addition of hydrogen to alkene)?

Answer 41

nickel catalyst, 200C

Question 42

what conditions are needed for fermentation of glucose?

Answer 42

37C, no oxygen, yeast as catalyst

Question 43

is nylon a polyester or a polyamide?

Answer 43

polyamide ## Footnote terylene is a polyester

Question 44

how does melting point change when a substance is impure?

Answer 44

melting point decreases | boiling point increases

Question 45

what substances can sublime?

Answer 45

iodine, ammonium chloride and dry ice (liquid carbon dioxide)

Question 46

what is the arrangement and movement of solids?

Answer 46

arrangement: particles are closely packed in a regular arrangement movement: vibrate & rotate about their fixed positions

Question 47

what is the arrangement and movement of liquids?

Answer 47

arrangement: less closely packed than in solid and in a disorderly arrangement movement: slide over neighbouring particles and move freely throughout the liquid

Question 48

what is the arrangement and movement of gas?

Answer 48

arrrangement: disorderly arranged and very far apart movement: move freely in all directions at high speeds

Question 49

what is the anode and cathode for electroplating?

Answer 49

cathode - object to be plated anode - pure plating metal

Question 50

why are noble gases unreactive?

Answer 50

noble gases have stable duplet or octet electronic configuration with fully filled electron shells, so they do not need to gain, lose or share electrons with other elements

Question 51

describe fractional distillation of crude oil

Answer 51

1. crude oil is heated and completely vaporised in the furnace. the column is cooler at the top than at the bottom. as the vapour rises, it cools and condenses 2. each fraction cools and condenses at a different temperature 3. hydrocarbons with short carbon chains and lower boiling points condense and escape from the top of the fractionating column 4. hydrocarbons with long carbon chains and higher boiling points condense and escape from the bottom of the fractionating column

Question 52

where do oxides of nitrogen come from?

Answer 52

lightning activity and internal combustion engines

Question 53

where does sulfur dioxide come from?

Answer 53

volcanic eruptions and combustion of fossil fuels

Question 54

why are oxides of nitrogen and sulfur dioxide bad?

Answer 54

- irritates lungs & eyes - causes respiratory difficulties - forms acid rain

Question 55

why is carbon monoxide bad?

Answer 55

combines irreversibly with haemoglobin in blood, reduces ability of haemoglobin to transport oxygen to rest of body, may result in death