heating xxx nitrate

There are four types of reaction in heating metal nitrates, mainly related to the reactivity of the metal. The reactive series of common metals that can form nitrates :
K, Na, Ca, Mg, Al, Zn, Cr, Fe, Sn, Ni, Pb, Cu, Hg, Ag

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Type 1 : KNO3 and NaNO3
Each of them decomposes to give sodium/potassium nitrite and oxygen gas.
2KNO3(s) → 2KNO2(s) + O2(g)
2NaNO3(s) → 2NaNO2(s) + O2(g)

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Type 2 : Ca(NO3)2, Mg(NO3)2 … Pb(NO3)2, Cu(NO3)2
Each of them decomposes to give a metal oxide, nitrogen dioxide gas, and oxygen gas.
2Ca(NO3)2(s) → 2CaO(s) + 4NO2(g) + O2(g)
……
……
2Cu(NO3)2(s) → 2CuO(s) + 4NO2(g) + O2(g)
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Type 3 : Hg(NO3)2 and AgNO3
Each of them decomposes to give a metal, nitrogen dioxide, and oxygen gas.
Hg(NO3)2(s) → Hg(l) + 2NO2(g) + O2(g)
2AgNO3(s) → 2Ag(s) + 2NO2(g) + O2(g)

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Type 4 : NH4NO3
It decomposes to give dinitrogen monoxide gas and water vapour. The reaction is sublimation.
NH4NO3(s) → N2O(g) + 2H2O(g)

in the metal reactivity series,K, Na, Ca, Mg, Al Zn, Fe, Pb, Cu, Hg, Ag, Au
when xxx=
--Ca
2XNO3 --> 2XNO2 + O2
Mg--Cu
4XNO3 --> 2X2O + 2NO2 + 3O2
Ag--
2XNO3 --> 2X + 2NO2 + O2