Chemistry-2 (Elements of Life)

Question 1

Colour change of phenolphthalein from acid to alkali

Answer 1

Red/ pink to clear

Question 2

Colour change of methyl orange from acid to alkali

Answer 2

Yellow to red

Question 3

What shape is the s orbital?

Answer 3

Spherical

Question 4

What shape is the p orbital?

Answer 4

Dumbbell

Question 5

What is a dative covalent bond?

Answer 5

When the electrons come from the same atom

Question 6

2 special cases of covalent bonding

Answer 6

BF3 boron only has 6 outer electrons not 8

SF6 sulfur has 12 outer electrons not 8

Question 7

Angle size of tetrahedral molecule

Answer 7

109.5

Question 8

Angle size of water

Answer 8

<109.5

104.5 due to lone pairs

Question 9

Draw a standard first ionisation enthalpy equation

Answer 9

X(g) —> x+(g) + e-

Question 10

Relationship of first ionisation enthalpy down group 1 and 2

Answer 10

Decreases

Question 11

First ionisation enthalpy trend across periods

Answer 11

Increases

Question 12

First ionisation enthalpy of group 1 high or low

Answer 12

Low

Question 13

How to detect carbonates?

Answer 13

Dilute HCl and carbonates will fizz and produce CO2

Then test for CO2 with lime water which will turn cloudy if present

Question 14

How to test for sulfates?

Answer 14

Add dilute HCl follow by Barium Chloride
If it forms a white precipitate of barium sulfate
( HCl added to get rid of traces of carbonate ions)

Question 15

Test for ammonium compounds

Answer 15

Ammonia gas is like an alkaline so can be checked using a damp piece of red litmus paper and will turn blue if present

Question 16

How to test for hydroxides?

Answer 16

Litmus paper

Red litmus paper will turn blue

Question 17

Test for halides

Answer 17

Add silver nitrate
Cl- Chlorine will form white precipitate
Br- Bromine will form cream precipitate
I- Iodine will form yellow precipitate

Question 18

How is energy related to frequency

Answer 18

E= hv
Plancks constant x freq

E= hc/ w
Plancks constant x speed of light/ wavelength

Question 19

Define elimination reaction

Answer 19

When a molecule is removed. Product becomes unsaturated. Double bond formed.

Question 20

Flame test for lithium

Answer 20

Crimson

Question 21

Flame test for sodium

Answer 21

Yellow

Question 22

Flame test for potassium

Answer 22

Lilac

Question 23

Flame test for calcium

Answer 23

Red

Question 24

Flame test for barium

Answer 24

Green

Question 25

Flame test for copper

Answer 25

Blue- Green

Question 26

Coloured precipitate by adding sodium hydroxide (NaOH) to Silver Ag 2+

Answer 26

Brown

Question 27

Coloured precipitate by adding sodium hydroxide (NaOH) to Calcium Ca2+

Answer 27

White

Question 28

Coloured precipitate by adding sodium hydroxide (NaOH) to Copper (II) Cu 2+

Answer 28

Blue

Question 29

Coloured precipitate by adding sodium hydroxide (NaOH) to Lead (III) Pb 2+

Answer 29

White

Question 30

Coloured precipitate by adding sodium hydroxide (NaOH) to Iron (II) Fe 2+

Answer 30

Green

Question 31

Coloured precipitate by adding sodium hydroxide (NaOH) to Iron (III) Fe 3+

Answer 31

Brown

Question 32

Coloured precipitate by adding sodium hydroxide (NaOH) to Zinc Zn 2+

Answer 32

White, in excess of NaOH is colourless

Question 33

Coloured precipitate by adding sodium hydroxide (NaOH) to Aluminium Al 3+

Answer 33

White, in excess of NaOH will turn colourless

Question 34

Describe metallic bonding

Answer 34

``` Between metals Sea of delicalised electrons Conduct Insoluble High MP 2+ higher than 1+ ```

Question 35

Describe ionic bonding

Answer 35

``` Metal and non metal Electrons transferred High MP Soluble Conduct when molten ```

Question 35

Describe ionic bonding

Answer 35

``` Metal and non metal Electrons transferred High MP Soluble Conduct when molten ```

Question 36

Describe simple covalent bonding

Answer 36

``` Between non metals Share electrons Low MP Don't conduct Insoluble ```

Question 37

Describe giant ionic lattices

Answer 37

Eg NaCl Very high MP Many ionic bonds

Question 38

Describe giant covalent bonding

Answer 38

``` Mainly carbon and silicon Don't conduct except graphite High MP Thermal conductors Insoluble ```

Question 39

How to calculate percentage composition?

Answer 39

Mass of element/ total mass of compound x100

Question 40

How to calculate empirical formula from percentage composition

Answer 40

Percentage, pretend it's in 100g, 1) Divide percent by Mr of element. 2) Divide by smallest number