CH8 reactivity trends

why are group 2 elements called reducing agents?

They have reduced another species meaning they have gained electrons while the group 2 elements would’ve lost 2 electrons.

What is a redox reaction?

A reaction undergoing reduction and oxidation

Equation for group 2 elements and oxygen

2Mg(s) + O2(g) > 2MgO(s)

Equation for group element with water

Mg(s) + 2H2O(l) > Mg(OH)2(aq) + H2(g)

Equation for group 2 element with dilute acids

Mg(s) + 2HCl(aq) > MgCl2(aq) + H2

Equation for group 2 oxides with water

MgO(s) + H2O(l) > Mg(OH)2(s)

What different colours form in the halogen halide displacement reactions?

Chlorine + bromide ions > orange

Chlorine + iodide ions > violet

Bromine + iodide ions > violet

Other combos = no reactions as the halogen added must be more reactive than the halide present

What is the correct sequence for analysing an unknown inorganic compound?

1)carbonate

2)Sulfate

3)halides

How to carry out carbonate test

1)add dilute nitric acid to test

2) if bubbles present, could be carbonate

3) test for CO2, bubble gas through limewater. If white precipitate forms, CO2 present.

How to carry out Sulfate test

1) add barium ions to solution of unknown compound

2) formation of a white precipitate indicates Sulfate present.

How to carry out halide test And test results

1) Add aqueous silver nitrate to solution

2) chloride present= white, bromide present= cream, iodide present= yellow

3) add aqueous ammonia it test solubility, chloride is soluble in dilute NH3, bromide is soluble in concentrated and iodide is insoluble.

How to carry out cation test (Ammonium ion)

1) add aqueous sodium hydroxide