Chapter 8

Question 1

What are physical properties of group 2 metals ?

Answer 1

• alkaline earth metals
• alkaline properties of the metal hydroxides
• elements of group 2 are reactive metals and do not occur naturally in elemental form
• usually found in stable compounds

Question 2

How do group 2 metals react with H2O and 02 ?

Answer 2

2Mg + 02 -> 2MgO

Mg + 2H2O -> Mg(OH)2 + H2

Question 3

What are the chemical trends in group 2 ?

Answer 3

• reactivity increases down the group due to decreasing ionisation energies
• solubility increases down the group, this is because X - OH bonds get more polar, the ions require less energy to separate.
• pH increases down the group
• Alkalinity increases down the group

Question 4

How does a group 2 oxide react with water ?

Answer 4

Question 5

What are the uses of group 2 compounds ?

Answer 5

The main uses of group 2 compounds are to neutralise acids, due to their alkaline properties e.g in agriculture and medicine

Question 6

What colour are the halogens in a halogen displacement reaction ?

Answer 6

Chlorine - colourless
Bromine - yellow
Iodine - purple

Question 7

How to do a halide test ?

Answer 7

• add dilute nitric acid
• add silver nitrate solution
• halide ions will react with the silver nitrate
• Ag+ + X- -> AgX, the silver halide will be a solid precipitate
• AgCl - white, AgBr - cream, AgI - yellow
• add dilute then concentrated ammonia to identify halide, if precipitation dissolves in dilute the halide is chloride, in concentrated the halide is bromide, if it doesn’t dissolve the halide is iodide

Question 8

How to test for carbonate ions ?

Answer 8

• add dilute nitric acid
• bubbles will indicate a carbonate could be present
• bubble the gas through lime water - Ca(OH)2
• lime water will go from colourless to cloudy if CO2 is present - (CaCO3) precipitate forms

Question 9

How to test for sulfate ions ?

Answer 9

• add dilute HCl
• add barium nitrate to the sample
• if sulfate ions are present, a white precipitate will form (BaSO4)

Question 10

What is the order of carry out ion tests ?

Answer 10

1) carbonate
2) sulfates
3) halides

Question 11

What is the test for ammonium ions ?

Answer 11

• add sodium hydroxide
• ammonia is soluble in water so may not be bubbles
• ammonia can be identified by smell, or turning damp red litmus paper blue due to it being alkaline