inorganic: trends in G2, alkaline earth metals

Question 1

why are they called alkaline earth metals

Answer 1

their oxides and hydroxides are alkaline

Question 2

explains g2 ionisation energy trend in terms of reactivity

Answer 2

the elements become more reactive down the group as the ionisation energy decreases down group as it becomes easier to removes outer two e-, doe to increasing nuclear charge and shielding there is a larger distance between outer e- and nucleus so less energy required to lose e-, it is more reactive down group since it is easier to lose the outer e-

Question 3

what reactions occur with g2 metals and
dilute HCL acid
oxygen

Answer 3

HCL- bubbles of h2 gas vigorous reaction
o2- more reactive down group

Question 4

explain trend of melting points down g2

Answer 4

strength of metalic bond decreases down group as nucleus is further from sea of delocalised e-/ outer e- so less attraction, easier to melt

Question 5

Explain the trend of solubility of OH in g2

Answer 5

going down the group they are more soluble and alkalinity increases
Mg(OH)2 milk of magnesia is not very soluble
Ca(OH)2 is lime water and isn sparingly soluble
Sr(OH)2 is more soluble
Ba(OH)2 is most soluble and dissolves to make a highly alkaline solution
Ba(OH)2 + aq—= Ba2+ + 2OH-

Question 6

Explain the trend of solubility of SO4^2- in g2

Answer 6

going down the group they are less soluble
BaSO4 insoluble- barium meal

Question 7

Mg reaction in water explain

Answer 7

Magnesium reacts extremely slowly with cold water:
Mg (s) + 2H2O (l) → Mg(OH)2 (aq) + H2 (g)

The solution formed is weakly alkaline (pH 9-10) as magnesium hydroxide is only slightly soluble
However, when magnesium is heated in steam, it reacts vigorously with steam to make magnesium oxide and hydrogen gas:
Mg (s) + H2O (g) → MgO (s) + H2 (g)

Question 8

what are the used of G2 metals

Answer 8

Mg can be sued to extract titanium in a displacement reaction from Ticl4
CaO reacts with SO2 to remove it forming calcium sulfite and water= flue gas
BaSo4 is insoluble so barium meal is used in medicine as it absorbs x ray but wont be absorbed into the bloods
MgOH is an antiacid so can be used fro digestion in medicine
CaCO3 lime water can be used to raise the pH in agriculture soils

Question 9

how is the insolubility of BaSO4 useful

Answer 9

can test for sulfate ions
solution is acidified to remove and carbonates or hydrogen as co2 which barium carbonate is a white solid so error test if not removed
barium chloride solution is added to test solution and barium will react in sulfate is present and form a white percipitate