F4 Chem M2O

M2O is an oxide of metal M. Upon heating, M2O decomposes to give M and oxygen only.

a) In an experiment, 3.48g of M2O completely decomposes to give 3.24g of M.
Calculate the relative atomic mass of M

2 M2O => 4 M + O2
mol of oxygen molecule released
=(3.48-3.24)/16=0.24/(16*2)=0.0075 mol
so 3.24 g M contain 0.015*4=0.03 mol M
atomic mass = 3.24/0.03 = 108

b) explain whether M can react with dilute hydrochloric acid.
No. From the periodic table, X is silver which cannot react with dilute HCl

(a)Atomic mass of oxygen = 162 M2O => 4 M + O23.48 g   =     3.24 g + 0.24 gIn the experiment, 3.48 g of  metallic oxide produces  3.24 g of metalMass of Oxygen produced = 3.48 g – 4.24 g = 0.24 gUsing simple ratio,2 M2O => 4 M + O23.48 g   =     3.24 g + 0.24 g             =      ?? g      + 32 gFind out the mass of 4 moles of M with 32 g of O2 produced3.24 g/0.24 x 32 g =432 g4 M = 432 g1M (one mole) = 432/4 = 108 g The metal is actually silver. (From periodic table)
(b) You have to look at the ACTIVITY SERIES.Li, K, Ba, Ca, Na, Mg, Al, Zn, Cr, Fe,  ….Pb ,HYDROGEN, Cu, Hg, Ag, GoldHydrogen, although not a metal, is included in the series.Any metal placed above hydrogen will generally react with acids such  as hydrochloric acid. Silver, Ag, is way  below  hydrogen and therefore will not react with hydrochloric acid.