8) While the hydroxides and carbonates of sodium and potassium are readily soluble in water, the corresponding salts of magnesium and calcium are only sparingly soluble. Thus stability of alkaline earth metal hydroxides decreases with decrease in lattice enthalpy as the size of alkali earth metal cations increases down the group. Thermal stability of alkali metal hydrides and carbonates (1 answer) Closed 1 year ago. However, due to the square factor, the lattice enthalpy decreases faster than the hydration enthalpy. Hydroxides are compounds that contain the OH − ion. From Li to Cs, thermal stability of carbonates increases. Thus stability of alkaline earth metal hydroxides decreases with decrease in lattice enthalpy as the size of alkali earth metal cations increases down the group.Jun 28, 2019 Like alkali metals, these are s-block elements, and have two electrons in the valence shell in s-orbital. For example, if sodium is the alkali metal: The stability of the peroxides and superoxides of the alkali metals increases as the size of the cation increases. Solubility and Stability of Alkali Metal Hydroxides All these hydroxides, except for lithium hydroxide, are highly water soluble and thermally stable. The thermal stability of carbonates increases with the increasing basic strength of metal hydroxides on moving down the group.Thus the order is The bicarbonates of all the alkali metals are known. Down the group, atoms of the alkali metals increase in both atomic and ionic radii, due to the addition of electron shells. If the answer is not available please wait for a while and a community member will probably answer this soon. Stability of carbonates increases down group I (alkali) and group II (alkaline earth) metals. (c) All the alkali metals on exposure to atmosphere (air and moisture) get converted into oxides, hydroxides and finally to carbonates. Arrange these in the order of decreasing solubility, and give reasons for each of the arrangement 7) In aqueous solution, the solubility of the alkali metal ions is given as … NaOH + HCI → NaCI + H 2 O Δ H f for L i C l = − 4 0 8. Doubtnut is better on App. Alkali metal - Alkali metal - Chemical properties: Since the alkali metals are the most electropositive (the least electronegative) of elements, they react with a great variety of nonmetals. 5 k J m o l − 1 Δ H f for C s C l = − 4 3 3 k J m o l − 1 are solved by group of students and teacher of NEET, which is also the largest student community of NEET. It is possible to prepare these compounds by two general types of reactions. The hydroxides of the alkali metals, lithium, sodium, potassium, rubidium, and cesium, are the strongest bases and the most stable and most soluble of the hydroxides. Metal hydroxides such as \(\ce{Fe(OH)3}\) and \(\ce{Al(OH)3}\) react with acids and bases, and they are called amphoteric hydroxide.In reality, \(\ce{Al(OH)3}\) should be formulated as \(\ce{Al(H2O)3(OH)3}\), and this neutral substance has a very low solubility. In group1,it is found that the thermal stability of hydroxides,carbonates,nitrates sulphates etc. The carbonates of group-2 metals and that of lithium decompose on heating, forming an oxide and carbon dioxide . They are generally soluble in water and stable towards heat. At the end of the chemical reaction, lithium gives lithium monoxide (LiO), sodium gives sodium peroxide (Na 2 O 2), and other alkali metals give superoxides (that is, each alkali metal atom forms bonds with two oxygen atoms). Reaction with Oxygen. The hydration enthalpy also decreases since the size of the cation increases. This can be explained as follows: The size of lithium ion is very small. Due to increased nuclear charge and smaller size, alkaline earth metals form compounds which are less ionic than the corresponding compounds of the alkali metals. Stability of compound depends upon its enthalpy of formation Δ H f . The alkali metals have the silver-like lustre, high ductility, and excellent conductivity of electricity and heat generally associated with metals. The carbonate ion has a big ionic radius so it is easily polarized by a small, highly charged cation. As a result, metals can easily lose an electron in order to obtain stability. The higher the temperature required to decompose something, the more thermally stable it will be. The melts of alkali metal hydroxide—nitrate systems are thermally stable to at least 300°C above the melting temperatures. Li forms Li 2 O, Na forms peroxides Na 2 O 2 and K, Rb and Cs forms superoxides KO 2, RbO 2 and CsO 2 respectively.. M (OH) 2 + H 2 SO 4 → MSO 4 + 2H 2 O MCO 3 + H 2 SO 4 → MSO 4 + CO 2 + H 2 O . 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