Alkaline earth metals

Question 1

Precipitation of Ca2+-ions as carbonates:

Answer 1

Ca2+(aq) + CO32–(aq) → CaCO3(s)
Ca(NO3)2 + Na2CO3 → CaCO3 + 2NaNO3

Question 2

Production of barium by thermite process:

Answer 2

3 BaO(s) + 2 Al(s) → Al2O3(s) + 3 Ba(s)

Question 3

Reaction of calcium with water:

Answer 3

Ca(s) + 2 H2O(l) → Ca2+(aq) + 2 OH–(aq) + H2(g)
Ca + 2 H2O → Ca(OH)2 + H2

Question 4

Reaction of magnesium with water:

Answer 4

Mg(s) + 2 H2O(l) → Mg2+(aq) + 2 OH–(aq) + H2(g)
Mg + 2 H2O → Mg(OH)2 + H2(g)

Question 5

Reaction of beryllium with alkali solution:

Answer 5

Be(s) + 2 OH–(aq) + 2 H2O(l) → Be(OH)42–(aq) + H2(g)
Be + 2 NaOH + 2 H2O → Na2[Be(OH)4] + H2(g)

Question 6

Production of beryllium chloride:

Answer 6

BeO(s) + C(s) + Cl2(g) → BeCl2(g) + CO(g)

Question 7

Decomposition of calcium carbonate:

Answer 7

CaCO3(s) → CaO(s) + CO2(g)

Question 8

Reaction of calcium oxide with water:

Answer 8

CaO(s) + H2O(l) → Ca2+(aq) + 2 OH–(aq)
CaO(t) + H2O(v) → Ca(OH)2

Question 9

Reaction of calcium hydroxide with carbon dioxide:

Answer 9

Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)

Question 10

Use of the quicklime for production of iron:

Answer 10

CaO(s) + SiO2(s) → CaSiO3(l)

Question 11

Use of the slaked lime to soften the water:

Answer 11

HCO3–(aq) + OH–(aq) → CO32–(aq) + H2O(l) Ca2+(aq) + CO32–(aq) → CaCO3(s)
Ca(HCO3)2 + Ca(OH)2 → 2 CaCO3 + 2 H2O

Question 12

Tooth decay under the influence of acids:

Answer 12

Ca5(PO4)3OH(s) + 4 H3O+(aq) → 5 Ca2+(aq) + 3 HPO42– (aq) + 5 H2O(l)
Ca5(PO4)3OH + 4 CH3COOH → 2 Ca(CH3COO)2 + 3 CaHPO4 + H2O