atmosphere and acids 3.4

Question 1

what’s the composition of the air?

Answer 1

nitrogen - 78 %
oxygen - 21 %
argon - 0.96 %
carbon dioxide - 0.04 %

Question 2

how can we measure the percentage of oxygen?

Answer 2

by reacting it with another element, and the air gradually decreases until all of the oxygen has been added to the element

to work out the percentage:
decrease in volume / initial volume of air x 100 = %

Question 3

why do some experiments fail?

Answer 3

leak in apparatus
wasn’t heated long enough for all the oxygen to be reacted

Question 4

what affect mass?

Answer 4

heating on yellow flame as the door adds to mass
not heating for long enough
something has escaped

Question 5

what is the equation for element combustion?

Answer 5

element + oxygen > element oxide

Question 6

what affects the name and state of the oxide?

Answer 6

whether it is a metal or non-metal
metal - oxide, solid
non-metal - dioxide, gas

Question 7

what’s important about the element combustion of magnesium?

Answer 7

produces a bright white light and white power

Question 8

what’s important about the element combustion of sulphur?

Answer 8

blue flame

Question 9

what’s important about the element combustion of hydrogen ?

Answer 9

squeaky pop

Question 10

what’s the charge of iron (||)?

Answer 10

Fe 2+

Question 11

what’s the charge of iron (|||)?

Answer 11

Fe 3+

Question 12

what’s the charge of copper?

Answer 12

Cu 2+

Question 13

what’s the charge of silver?

Answer 13

Ag +

Question 14

what’s the charge of zinc?

Answer 14

Zn 2+

Question 15

what’s the charge of lead?

Answer 15

Pb 2+

Question 16

what’s the chemical test for oxygen?

Answer 16

glowing splint > relights
as the oxygen allows the wood in splint to combust more efficiently

Question 17

what type of solution does a metal oxide form?

Answer 17

alkaline solution

Question 18

what type of solution does a non-metal dioxide form?

Answer 18

acidic solution

Question 19

what’s the acid name, acid formula and ion formula for nitrate?

Answer 19

nitric acid
HNO3
NO3 -

Question 20

what’s the acid name, acid formula and ion formula for sulphate?

Answer 20

sulphuric acid
H2SO4
SO4 2-

Question 21

what’s the acid name, acid formula and ion formula for phosphate?

Answer 21

phosphoric acid
H3PO4
PO4 3-

Question 22

what’s the acid name, acid formula and ion formula for carbonate?

Answer 22

carbonic acid
H2CO3
CO3 2-

Question 23

what’s the alkali name, alkali formula and ion formula for ammonium?

Answer 23

ammonium hydroxide
NH4OH
NH4 +

Question 24

what’s the ion formula for hydroxide?

Answer 24

OH -

Question 25

what’s the chemical test for carbon dioxide?

Answer 25

limewater > turns cloudy CO2 reacts with the limewater to insoluble white solid

Question 26

a pH greater than 7 is ...

Answer 26

alkaline

Question 27

a pH of 7 is ...

Answer 27

neutral

Question 28

a pH less than 7 is ...

Answer 28

acidic

Question 29

in an acidic solution methyl orange indicator would turn:

Answer 29

red

Question 30

in an neutral solution methyl orange indicator would turn:

Answer 30

yellow

Question 31

in an alkaline solution methyl orange indicator would turn:

Answer 31

yellow

Question 32

in an acidic solution phenolphthalein indicator would turn:

Answer 32

colourless

Question 33

in an neutral solution phenolphthalein indicator would turn:

Answer 33

colourless

Question 34

in an alkaline solution phenolphthalein indicator would turn:

Answer 34

pink

Question 35

in an acidic solution red litmus paper would turn:

Answer 35

stay red

Question 36

in an neutral solution red litmus paper would turn:

Answer 36

stay red

Question 37

in an alkaline solution red litmus paper would turn:

Answer 37

blue

Question 38

in an acidic solution blue litmus paper would turn:

Answer 38

red

Question 39

in an neutral solution blue litmus paper would turn:

Answer 39

stay blue

Question 40

in an alkaline solution blue litmus paper would turn:

Answer 40

stay blue

Question 41

universal indictor range of colours depending on pH:

Answer 41

0,1,2 : red 3,4 : orange 5,6 : yellow 7 : green 8,9,10 : light blue 11,12,13: dark blue 14 : purple

Question 42

how do you determine whether an unknown element is a metal or non-metal?

Answer 42

1. combust in it oxygen 2. dissolve the oxide formed 3. check the pH of the solution with an indicator metal oxide - alkaline solution non- metal dioxide - acidic solution

Question 43

what is the acid and base reaction?

Answer 43

acid + base > salt + water for example sulphuric acid + zinc oxide > zinc sulphate + water

Question 44

what is an important observation in an acid + base reaction?

Answer 44

base disappears this is because it is used up in reaction

Question 45

what do you need to remember about the salt formed from a base and acid reaction?

Answer 45

if salt is soluble, it dissolves to form a salt solution

Question 46

we can use an acid + base reaction to make ...

Answer 46

salt crystals

Question 47

how do you make zinc sulphate crystals?

Answer 47

1. add excess base (ZnO) to hot acid (H2SO4) this makes sure that the salt solution is made quickly and ensures all the acid is used up 2. filter out the excess base (ZnO) salt solution (ZnSO4) is the filtrate and is collected in an evaporating basin 3. heat salt solution (ZnSO4) until crystals start to from around the edges this saturates the solution so that crystals form most efficiently 4. leave salt solution to crystallise evaporation of water allows crystals to form

Question 48

what is the acid and carbonate reaction?

Answer 48

acid + carbonate > salt + water + carbon dioxide for example lead carbonate + sulphuric acid > lead sulphate + water + carbon dioxide

Question 49

what are the two important observations in an acid + carbonate reaction?

Answer 49

carbonate disappears - as it is used up in reaction fizzing - as gas of carbon dioxide is produced

Question 50

what do you need to remember about the salt formed from a carbonate and acid reaction?

Answer 50

if salt is soluble, it dissolves to form a salt solution