Starting with CaCO3, write balanced chemical equation showing the preparation of:
(i) CaO (ii) CaSO4 (iii) Ca(OH)2 (iv) Ca(HCO3)2 solution.
Describe two important uses of the following;
(a) Caustic soda (b) Sodium carbonate (iii) Quick lime.
What happens when,
(i) magnesium is burnt in air
(ii) quick- lime is heated with silica
(iii) chlorine reacts with slaked lime
(iv) calcium nitrate is heated?
Discuss the composition and manufacturing details of cement.
Or
Mention the main constituents of Portland cement.
Contrast the action of heat on the following and explain your answer:
(i) Na2CO3 and CaCO3
(ii) MgCl2.6H2O and CaCl2.6H2O
(iii) Ca(NO3)2 and NaNO3.
Explain the significance of magnesium and calcium in biological fluids.
Significance of magnesium and calcium:
(i) Magnesium is an important constituent of chlorophyll which initiates the process of photosynthesis in green plants.
(ii) Magnesium ions are concentrated more in intracellular than in extracellular fluids in animal bodies. Their presence is also necessary for the activation of phosphate-transfer enzymes. These enzymes take part in the biochemical process (exothermic) occurring in animal body. Mg2+ ions are also involved in carbohydrates metabolism.
(iii) Ca2+ ions are essential for the formation of bones and teeth. The enamel on teeth is a double salt 3Ca3(PO4)2.CaF2.
(iv) Mg2+ and Ca2+ ions are also involved in the transmission of electrical impulses along the nerve fibre and for the contraction of muscles.
Discuss the general characteristics and gradation in properties of alkaline earth metals.
Compare the alkali metals and alkaline earth metals with respect to (i) ionisation enthalpy (ii) basicity of oxides and (iii) solubility of hydroxides.