Question

during boiling of Mg(hco3) why mg(oh)2 is formed instead of mg(co3).

Answer 1

MgHCO3 reacts with H20 to form Mg(OH)2 and H2CO3 it is due to dissociation of water molecules into H+ and OH-. Here H+ attacks HCO3- and forms H2CO3 and OH- attacks Mg to form Mg(OH)2.