Chem Paper 1

Question 1

pH=?

Answer 1

-log[H+]

Question 2

Kw=?

Answer 2

[H+][OH-]

Question 3

Ka=?

Answer 3

[H+][X-]
______________
[HX]

Question 4

pKa=?

Answer 4

-log(Ka)

reverse applies as well

Question 5

pH of diluted acid

Answer 5

[H+] (old) x old volume/new volume

Question 6

define Bronsted lowry acid

Answer 6

proton donator eg: HCl

Question 7

define bronsted lowry base

Answer 7

proton acceptor eg: NH3

Question 8

Period 3 Oxide Melting points

Answer 8

Na2O: 1250
MgO: 2900
Al2O3: 2040
SiO2: 1610
P4O10: 580
SO2: -75
SO3: 17

Question 9

2Na + 2H2O

Answer 9

2NaOH +H2

Yellow flame

Question 10

Mg + H20(g)

Answer 10

MgO + H2

White flame - white powder

Question 11

Mg + 2H2O(l)

Answer 11

Mg(OH)2 + H2

VERY SLOW

Question 12

4Na + O2

Answer 12

2Na2O

yellow orange flame + white powder

Question 13

2Mg + O2

Answer 13

2MgO

white flame + white powder

Question 14

4Al3 + 3O2

Answer 14

2Al2O3

white flame + white powder

Question 15

Si + O2

Answer 15

SiO2

white flame + white powder

Question 16

P4 + 5O2

Answer 16

P4O10

bright white flame + white powder

Question 17

S + O2

Answer 17

SO2

blue flame + choking gas

Question 18

Group 2 trend (Atomic Radius)

Answer 18

AR increases down the group

Question 19

Group 2 1.I.E.

Answer 19

Decreases down the group
More shielding
weaker attraction between nucleus and outer electrons
outer electrons are fuirther from nucleus so weaker attraction
ANOMALIES AT MG AND S

Question 20

Group 2 Melting points

Answer 20

Generally decreases
G2 elements form metallic structures
Size of metal ion increases but number of delocalised electrons remain same
So larger distance between nucleus and del.elec so weaker attractive force

Mg is an exception due to structural arrangement

Question 21

Reactions with water

M + 2H2O

Answer 21

M(OH)2 + H2

no reaction with Be v

Question 22

Trend G2 Hydroxide solubility

Answer 22

Mg: Not soluble -> Ba: Very soluble

Question 23

Trend G2 Sulphate solubility

Answer 23

Mg: Very soluble -> Ba: Not soluble

Question 24

Test for sulphate

Answer 24

Add HCl to react away carbonates
Add BaCl
White ppt if sulphate present

Question 25

Use of Ca(OH)2

Answer 25

Neutralise acidic soils

Question 26

Use of Mg(OH)2

Answer 26

Neutralise xs stomach acid as an antacid

Question 27

Use of BaSO4

Answer 27

Barium meal used to identify problems with digestive tract
X-rays are absorbed by BaSO4

Question 28

Extraction of titanium

Answer 28

Mg used to extrace titanium from TiO2
TiO2 reacted with carbon and chlorine gas
Fractional distillation to increase purity
Reduce TiCl4 using Mg in 1000c furnace
TiCl4 + 2Mg -> Ti + 2MgCl2

Question 29

CaCO3 and CaO to remove SO2 emissions

Answer 29

Wet scrubbing to neutralise SO2
Spray calcium soln onto SO2 gas.

Question 30

[Fe(H2O)6]2+

NaOH drop wise then XS

Answer 30

Dropwise: green ppt
XS: No further reaction

Question 31

[Fe(H2O)6]2+

NH3 dropwise then XS

Answer 31

Dropwise: green ppt [Fe(H2O)4(OH)2]
XS: No further reaction

Question 32

[Fe(H2O)6]2+

Add CO32-

Answer 32

green ppt FeCO3

Question 33

[Fe(H2O)6]2+

Add conc HCl

Answer 33

[FeCl4]2- yellow soln

Question 34

You Better Get Vanadium

Answer 34

Ends with V2+

Question 35

[Cu(H2O)6]2+

Add NH3 dropwise then XS

Answer 35

Dropwise: Blue ppt
XS: Royal blue solution [Cu(NH3)4(H2O)2]2+

Question 36

Also applies to Cl

NaF + H2SO4

Answer 36

NaHSO4 + HF

Question 37

NaBr + H2SO4
2 HBr + H2SO4

Answer 37

NaHSO4 + HBr
Br2 + SO2 + 2H2O

Question 38

NaI + H2SO4
2HI + H2SO4
6HI + SO2

Answer 38

NaHSO4 + HI
I2 + SO2 + 2H2O
H2S + 3I2 + 2H2O

Question 39

no uv/sunlight

Cl2 + H2O

Answer 39

ClO- + Cl- + 2H+

Question 40

in presence of UV light

2Cl2 + 2H2O

Answer 40

4HCl + O2

Question 41

NO PRoblem

Answer 41

Negative half cell is oxidised
Positive half cell is reduced

Question 42

cell notation

Answer 42

reduced/oxidised//oxidised/reduced

NEGATIVE HALF CELL ON THE LEFT