3.4 - Atmosphere + Acids

Question 1

four most abundant gases in dry air by percentage

Answer 1

78%​ ​nitrogen
21%​ ​oxygen
​0.9%​ ​argon​
​0.037%​ ​carbon​ ​dioxide

Question 2

how to determine volume of oxygen in air using copper

Answer 2

●​air​ ​passed​ over​ ​copper​ ​being​ ​heated​ ​with​ ​a Bunsen​ ​burner
● All​ ​oxygen​ ​in​ ​air​ ​will​ ​react​ ​with​ ​copper
● As​ ​it​ ​is​ ​passed,​ ​the​ ​volume​ ​of​ ​air​ ​will​ ​decrease
● Continued​ ​until​ ​the​ ​volume​ ​stops​ ​decreasing,​ ​then​ ​record​ ​the​ ​volume​ ​of
remaining​ ​air
● There​ ​would​ ​be​ ​about​ ​79cm3​ ​​ ​left,​ ​showing​ ​that​ ​21cm3​ ​​ ​of​ ​the​ ​original​ ​100cm3​ ​​ ​of air​ ​was​ ​oxygen
● The​ ​reaction​ ​happening​ ​in​ ​this​ ​case​ ​(with​ ​copper)​ ​is:
​ ​copper​ ​+​ ​oxygen​ ​->​ ​copper​ ​(II)​ ​oxide​ ​//​ ​2Cu​ ​(s)​ ​+​ ​O​2​​ ​(g)​ ​->​ ​CuO​ ​(s)
- Would​ ​notice​ ​black​ ​copper​ ​oxide​ ​forming

Question 3

describe combustion of elements in oxygen

Answer 3

combustion is an example of oxidation
oxidation -> gains oxygen

Question 4

combustion of elements in magnesium

Answer 4

2Mg + O2 –> 2MgO

Question 5

combustion of elements in hydrogen

Answer 5

2H2 + O2 –> 2H2O

Question 6

combustion of elements in sulfur

Answer 6

S + O2 –> SO2

Question 7

describe formation of carbon dioxide from thermal decomposition of metal carbonates
-> copper (III) carbonate

Answer 7

metal carbonate —> metal oxide + carbon dioxide
e.g. copper (III) carbonate
CuCO3 –> CuO + CO2

Question 8

carbon dioxide is a

Answer 8

green house gas

Question 9

greenhouse gas effect

Answer 9

o Electromagnetic​ ​radiation​ ​at​ ​most​ ​wavelengths​ ​from​ ​the​ ​sun​ ​passes through​ ​the​ ​Earth’s​ ​atmosphere
o The​ ​Earth​ ​absorbs​ ​some​ ​radiation​ ​and​ ​thus​ ​warms​ ​up​ ​(essential​ ​for​ ​life​ ​on Earth).​ ​But​ ​some​ ​heat​ ​is​ ​radiated​ ​from​ ​the​ ​Earth​ ​as​ ​infrared​ ​radiation.
o Some​ ​of​ ​this​ ​IR​ ​radiation​ ​is​ ​absorbed​ ​by​ ​greenhouse​ ​gases​ ​in​ ​the atmosphere
o Atmosphere​ ​warms​ ​up​ ​leading​ ​to​ ​the​ ​greenhouse​ ​effect​ ​and​ ​global warming

Question 10

phenolphthalein in alkaline

Answer 10

pink

Question 11

phenolphthalein in acid

Answer 11

colourless

Question 12

methyl orange in alkaline

Answer 12

yellow

Question 13

methyl orange in acid

Answer 13

red

Question 14

blue litmus paper in alkaline

Answer 14

stays blue

Question 15

blue litmus paper in acid

Answer 15

red

Question 16

red litmus paper in alkaline

Answer 16

stays red

Question 17

red litmus paper in acid

Answer 17

blue

Question 18

pH 7

Answer 18

neutral

Question 19

< pH 7

Answer 19

acidic

Question 20

> pH 7

Answer 20

alkaline

Question 21

use of universal indicator to measure pH of aq solution

Answer 21

• add solution to universal indicator paper and observe colour based on pH scale

Question 22

acids produce what ions

Answer 22

H+ in aqueous solutions

Question 23

alkalis produces what ions

Answer 23

OH- in aqueous solutions

Question 24

alkalis can neutralise acids with what equation

Answer 24

• between an acid and base
  H+(aq) + OH-(aq) –> H2O(l)

Question 25

acids in terms of proton transfer

Answer 25

donates H+

Question 26

bases in terms of proton transfer

Answer 26

accepts H+

Question 27

acids are proton

Answer 27

donors

Question 28

bases are proton

Answer 28

acceptors

Question 29

acid + base -->

Answer 29

salt + water

Question 30

acid + metal -->

Answer 30

salt + hydrogen

Question 31

acid + metal carbonate -->

Answer 31

salt + water + carbon dioxide

Question 32

how to form formula of the salt

Answer 32

take out the H

Question 33

alkalis are ____ that are ___ in water

Answer 33

bases that are soluble in water

Question 34

metal oxides, metal hydroxides and ammonia can act as

Answer 34

bases

Question 35

experiment to prepare a pure, dry sample of soluble salt from an insoluble reactant - use for copper(II) sulphate crystals starting with copper(II) oxide

Answer 35

- add excess insoluble base to acid - filter to remove unreacted base - heat solution so water evaporates and crystals of salt remain

Question 36

experiment to prepare a pure, dry sample of a soluble salt from an acid and alkali

Answer 36

- use titration to find exact volume of alkali that reacts with acid - mix exact vol of acid and base - warm solution so water evaporates and crystals remain

Question 37

experiment to prepare a pure, dry sample of a insoluble salt starting from two soluble reactants - used for dry lead (II) sulphate

Answer 37

- mix solutions of 2 soluble reactions - filter mixture so insoluble salt remains - wash with distilled water - leave to dry

Question 38

salts that are soluble

Answer 38

sodium potassium ammonium nitrates

Question 39

chlorides are all soluble except

Answer 39

silver lead

Question 40

sulphates are all soluble except

Answer 40

lead barium calcium