The stability of carbonates and bicarbonates increases down the group. 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. The solubility of carbonates decreases from Be to Ba. The carbonates of alkaline earth metals can be regarded as salts of weak carbonic acid (H 2 CO 3) and metal hydroxide, M(OH) 2. Compare the solubility and thermal stability of the following compounds of the alkali metals with those of the alkaline earth metals. Data on some, such as cesium and rubidium fluoride, nitrate, carbonate, and sulfate, appear to be reported for the first time. 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 carbonates of group-2 metals and that of lithium decompose on heating, forming an oxide and carbon dioxide . The alkali metals combine directly with halogens under appropriate conditions forming halides of general formula MX. Carbonates exist as solid and insoluble in water. Solubility of the carbonates. Carbonates of metal: Thermal stabilityThe carbonates of alkali metals except lithium carbonate are stable to heat. What makes the alkali metals so special? (c)Sulphate-thermal stability is good for both alkali and alkaline earth metals. 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 the alkaline earth metals of group 12 and lead(II) are not soluble. These carbonates precipitate upon mixing a solution of soluble alkali metal carbonate with a solution of soluble salts of these metals. These halides can also be prepared by the action of aqueous halogen acids (HX) on metals oxides, hydroxides or carbonate. But carbonates of alkaline earth metals are insoluble in water. Magnesium carbonate (the most soluble one I have data for) is soluble to the extent of about 0.02 g … The carbonates tend to become less soluble as you go down the Group. (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. Abstract. Properties of Sulphates of Alkali Earth Metals. Alkali metal sulphates are more soluble in water than alkaline earth metals. There's a certain solubility rule stating all carbonates, phosphates and hydroxides are insoluble unless mixed with hydroxides or alkali metals. Solubility: The solubility of the sulphates in water decreases down the groups i.e. 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:- … Halides of Alkali Metals. In the presence of carbon dioxide, carbonates dissolve by forming bicarbonates. None of the carbonates is anything more than very sparingly soluble. Be > Mg > Ca > Sr > Ba. The carbonates decompose on heating form metal oxide and CO 2 . Ionic character and the thermal stability of the carbonates increases from Be to Ba. Sulphates. Why is this? The sulphates of alkaline earth metals are all white solids. Examples of net ionic equations for the reactions are: The solubility of carbonates increases down the group in alkali metals (except ) . M 2 O + 2HX → 2MX + H 2 O . 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