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(a) Give reactivity of alkaline earth metals towards air, water, dihydrogen and acids.(b) Explain reducing nature of alkaline earth metals. (c) Give chemical reaction of alkaline earth metals with liquid ammonia.

Answer» <html><body><p></p>Solution :(i) <a href="https://interviewquestions.tuteehub.com/tag/reactivity-1178275" style="font-weight:bold;" target="_blank" title="Click to know more about REACTIVITY">REACTIVITY</a> towards air and <a href="https://interviewquestions.tuteehub.com/tag/water-1449333" style="font-weight:bold;" target="_blank" title="Click to know more about WATER">WATER</a> : Beryllium and magnesium are kinetically inert to oxygen and water because of the formation of an oxide film on their surface.<br/> However, powdered beryllium burns brilliantly on ignition in air to give Beo and `Be_(3)N_(2)`. <br/>Magnesium is more electropositive and burns with dazzling brilliance in air to give Mgo and `Mg_(3)N_(2)`. <br/>Calcium, strontium and barium are readily attacked by air to form the oxide and nitride. They also react with water with increasing vigour even in cold to form hydroxides. <br/>(ii) Reactivity towards the halogens : All the alkaline earth metals combine with <a href="https://interviewquestions.tuteehub.com/tag/halogen-1015106" style="font-weight:bold;" target="_blank" title="Click to know more about HALOGEN">HALOGEN</a> at elevated temperatures forming their halides.<br/> `M+X_(2) to MX_(2)(X=F, Cl, Br, I)` <br/>Thermal decomposition of `(NH_(4))_(2), BeF_(4)`is the best route for the preparation of `BeF_(2),and BeCl_(2)` is conveniently made from the oxide. <br/>`BeO+C+Cl_(2)overset(600-800K)hArr BeCl_(2) +CO` <br/>(iii) Reactivity towards hydrogen : All the elements except beryllium combine with hydrogen upon heating to form their hydrides, `MH_(2). BeH_(2)`,however, can be prepared by the reaction of `BeCl_(2)`with `LiAlH_(4)`.<br/> `2BeCl_(2) + LiAlH_(4) to 2BeH_(2) + LiCl + AlCl_(3)` <br/>(iv) Reactivity towards acids : The alkaline earth metals readily react with acids liberating dihydrogen.<br/> `M + 2HCl toMCl_(2) + H_(2)` <br/>(v) Reducing nature : Like alkali metals, the alkaline earth metals are strong reducing agents. This is indicated by large <a href="https://interviewquestions.tuteehub.com/tag/negative-570381" style="font-weight:bold;" target="_blank" title="Click to know more about NEGATIVE">NEGATIVE</a> values of their reduction potentials. However their reducing power is less than those of their corresponding alkali metals.<br/> Beryllium has less negative value compared to other alkaline earth metals. However, its reducing nature is due to large hydration energy associated with the small size of`Be^(2+)`ion and <a href="https://interviewquestions.tuteehub.com/tag/relatively-621723" style="font-weight:bold;" target="_blank" title="Click to know more about RELATIVELY">RELATIVELY</a> large value of the atomization enthalpy of the metal.<br/> (vi) Solutions in liquid ammonia: Like alkali metals, the alkaline earth metals dissolve in liquid ammonia to give deep blue black solutions forming ammoniated ions. From these solutions, the ammoniates, `[M(NH_(3))_(6)]^(2+)`can be recovered.<br/>`M_((s))+(x+y) NH_(3) to [M(NH_(3))_(x)]^(2+)+2[e(NH_(3))_(y)]^(-)`</body></html>


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