Ionic character and the thermal stability of the carbonates increases from Be to Ba. Properties of Sulphates of Alkali Earth Metals. Carbonates of metal: Thermal stabilityThe carbonates of alkali metals except lithium carbonate are stable to heat. Why is this? Be > Mg > Ca > Sr > Ba. Solubility: The solubility of the sulphates in water decreases down the groups i.e. None of the carbonates is anything more than very sparingly soluble. Carbonates exist as solid and insoluble in water. These carbonates precipitate upon mixing a solution of soluble alkali metal carbonate with a solution of soluble salts of these metals. … M 2 O + 2HX → 2MX + H 2 O . Alkali metals hydroxides are very strong bases, highly soluble in water and are not decomposed on heating.However, LiOH decomposes on heating to give because latter is more stable than former. The solubility of carbonates decreases from Be to Ba. Among the carbonate melts, the class of alkali metal carbonates (Li 2 CO 3, Na 2 CO 3i and K 2 CO 3) and their mixtures are the most prominent.These melts are fairly stable in the temperature range of 400 to 1000°C, exhibit low vapor pressures, can be easily contained in common ceramic and alloy materials, and are environmentally safe. Halides of Alkali Metals. (a) Nitrates (b) Carbonates (c) Sulphates Answer: (a) Nitrates of both group 1 and group 2 elements are soluble in water because hydration energy is more than the lattice energy. These halides can also be prepared by the action of aqueous halogen acids (HX) on metals oxides, hydroxides or carbonate. The carbonates of the alkaline earth metals of group 12 and lead(II) are not soluble. The stability of carbonates and bicarbonates increases down the group. There's a certain solubility rule stating all carbonates, phosphates and hydroxides are insoluble unless mixed with hydroxides or alkali metals. (c)Sulphate-thermal stability is good for both alkali and alkaline earth metals. Their basic strength increases from LiOH to CsOH due to a corresponding decresae in the I.E., of the metal in a group,i.e., the order:- Solubilities of the halides, nitrates, carbonates, sulfates, and some perchlorates of all the alkali metals and alkaline earth metals in methanol at room temperature have been determined. The carbonates of group-2 metals and that of lithium decompose on heating, forming an oxide and carbon dioxide . Alkali metal sulphates are more soluble in water than alkaline earth metals. Data on some, such as cesium and rubidium fluoride, nitrate, carbonate, and sulfate, appear to be reported for the first time. Abstract. The alkali metals combine directly with halogens under appropriate conditions forming halides of general formula MX. The solubility of carbonates increases down the group in alkali metals (except ) . Solubility of the carbonates. 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