Group 4

Question 1

Deduct an experiment to compare the thermal stability of two different group 2 nitrates

Answer 1

Put same amount of nitrate in a test tube
Heat both using a Bunsen burner
Use a gas syringe and measure rate of production of gas

Question 2

Explain the origin of flame test colours

Answer 2

Heat is transferred from heating when Bunsen burner is turned on
Electrons promoted to higher energy levels
Electrons return to lower energy levels
Light is emitted and released

Question 3

Explain the trend of electron affinities down group 7

Answer 3

Electron affinity becomes less negative/exothermic
Atomic radius increases
Less electrostatic attraction between nucleus and outer electron
Increased shielding from inner electrons
Increased shielding outweighs effect of nuclear charge

Question 4

What does group 2 metal add water form

Answer 4

Metal hydroxide and H2

Question 5

What colour are group 2 oxides

Answer 5

They are white solids

Question 6

What is formed when metal oxide is added to water

Answer 6

Metal hydroxide

Question 7

Explain the solubility of group 2 hydroxides and sulfated down the group

Answer 7

Group 2 sulfates decrease in solubility down the group
Group 2 hydroxides increase in solubility down the group

Question 8

Explain the 2 ways to Test for Nitrate ions

Answer 8

1)Measure how long it takes for a specific amount of oxygen to be produced. Use a gas syringe or amount needed to relight a growing splint

2) measure how long it takes for a specific amount of NO2 to be produced
NO2 is a brown gas so easily observed but must be done in a fume cupboard as it is toxic

Question 9

Test for carbonate ions

Answer 9

Measure length of time it takes for a specific amount of CO2 to be produced
CO2 turns limewater cloudy

Question 10

Colours of halogens

Answer 10

Fluorine is yellow
Chlorine is pale green
Bromine is brown orange
Iodine is grey solid

Question 11

Write a general equation when a halogen reacts with COLD ALKALIS in a disproportionation reaction

Answer 11

X2 + 2NaOH —> NaOX + NaX + H2O

Question 12

What’s the general equation when a halogen reacts with HOT Alkalis in a disproportionation reaction

Answer 12

3X2 + 6NaOH —> NaOX3 + 5NaX + 3H2O

Question 13

How is bleach(NaClO) made and what are the products

Answer 13

Made via Sodium hydroxide(2 moles) plus Cl2

Products: H2O,bleach and NaCl

Chlorine is oxidised and reduced

Question 14

Explain the trend of reducing agents down group 7

Answer 14

Reducing power increases down the group

Talk about atomic radius shielding proton number etc

Question 15

Test for Halide ions

Answer 15

Add HNO3 and Silver Nitrate solution to a solution of the ion.

I- are yellow(insoluble in concentrated NH3)
Cl- are white (precipitate dissolves in dilute NH3)
Br- are cream(dissolves in concentrated NH3)

Question 16

Magnesium plus steam forms..

Answer 16

MgO not Mg(OH)2

Question 17

Group 2 Metal oxide plus water forms

Answer 17

Metal hydroxide

Question 18

H2SO4 + NaX →
X is a halogen specifically Cl,Br,I

Answer 18

NaHSO4 + HX

X is a halogen specifically Cl,Br,I

Question 19

Test for Carbonates

Answer 19

HCl reacts with Carbonates and hydrogencarbonates to make CO2 gas
Bubble through limewater
Positive result is a cloudy colour

Question 20

Test for sulfates

Answer 20

Add HCl to the compound to remove any Carbonates
Add barium chloride
White precipitate produced

Question 21

Test for ammonium compounds(Litmus paper test)

Answer 21

1. Add NaOH to compound, gently heat using Bunsen burner
2. If Ammonium compound is present, ammonia gas produced
   Use damp red litmus paper,
   Ammonia will dissolve and turn blue

Question 22

Ionic equation between ammonium compound and hydroxide

Answer 22

NH4+ + OH- → NH3 + H2O

Question 23

Test for ammonium hydroxide
Will this test guarantee that the compound is ammonium hydroxide

Answer 23

Same as test for ammonium compound
Red litmus paper will turn blue as hydroxides are alkaline

Since litmus paper turns blue for any alkaline further tests are needed to confirm you have an alkali

Question 24

Explain why the reaction between metal oxides and silicon dioxide is necessary

Answer 24

Neutralisation reaction
Metal oxides are corrosive
Salt silicates that are inert form

Question 25

Which metals hydroxides are more soluble Group 1 or Group 2

Answer 25

Group 1

Question 26

Do Group 2 hydroxides increases in solubility down the group? What about Group 2 sulfates

Answer 26

Group 2 hydroxides increases in solubility down the Group(-1 charge) Group 2 sulfates decreases in solubility down the group

Question 27

When testing for halide ions we use Nitric acid first then Silver Nitrate Why do we use Nitric acid?

Answer 27

We use nitric acid so it can react with any other anions(other than halides) that are present in the reaction This prevents a false test

Question 28

What is the Further ammonia test for AgCl(white precipitate)

Answer 28

Cl- white precipitate dissolves in DILUTE NH3

Question 29

What is the Further ammonia test for AgBr(cream precipitate)

Answer 29

Cream precipitate dissolves in concentrated NH3

Question 30

What is the Further ammonia test for AgI(yellow precipitate)

Answer 30

Insoluble in CONCENTRATED NH3