question_answer

Magnesium metal burns in air to give a white ash. When this ash is treated with water, the odour of ammonia can be detected. Explain.

Answer:

                Mg bums in air to form MgO and \[M{{g}_{3}}{{N}_{2}}\]. \[2Mg+{{O}_{2}}\xrightarrow{\Delta }\,2\,MgO\,\,\,;\]\[3\ Mg+{{N}_{2}}\xrightarrow{\Delta }\,M{{g}_{3}}{{N}_{2}}\] Magnesium nitride on hydrolysis with \[{{H}_{2}}O\]gives \[N{{H}_{3}}\]. \[M{{g}_{3}}{{N}_{2}}+6\,{{H}_{2}}O\xrightarrow{\,}\,3\,Mg{{(OH)}_{2}}+\,2\,N{{H}_{3}}\]