Ar(N)=14; Mr(N)=14
Ar(Cu)=64; Mr(Cu)=64
Ar(Fe)=56; Mr(Fe)=56
Ar(Ag)=108; Mr(Ag)=108
Ar(O)=16; Mr(O2)=16*2=32
Ar(N)=14; Mr(N2)=14*2=28
Ar(F)=19; Mr(F2)=19*2=38
Ar(Cl)=35.5; Mr(Cl2)=35.5*2=71
Ar(C)=12; Ar(O)=16; Mr(CO2)=12+16*2=44
Ar(Na)=23; Ar(O)=16; Mr(Na2O)=23*2+16=46+16=62
Ar(N)=14; Ar(H)=1; Mr(NH3)=14+1*3=17
Ar(H)=1; Ar(S)=32; Mr(H2S)=1*2+32=34
Ar(H)=1; Ar(N)=14; Ar(O)=16; Mr(HNO3)=1+14+16*3=63
Ar(H)=1; Ar(S)=32; Ar(O)=16; Mr(H2SO4)=1*2+32+16*4=98
Ar(Ca)=40; Ar(C)=12; Ar(O)=16; Mr(CaCO3)=40+12+16*3=100
Ar(K)=39; Ar(P)=31; Ar(O)=16; Mr(K3PO4)=39*3+31+16*4=212
Ar(Zn)=65; Ar(O)=16; Ar(H)=1; Mr(Zn(OH)2)=65+16*2+1*2=99
Ar(Al)=27; Ar(O)=16; Ar(H)=1; Mr(Al(OH)3)=27+16*3+1*3=78
Ar(Mg)=24; Ar(N)=14; Ar(O)=16; Mr(Mg(NO3)2)=24+14*2+16*3*2=148
Ar(Fe)=56; Ar(S)=32; Ar(O)=16; Mr(Fe2(SO4)3)=56*2+32*3+16*4*3=400
Mg + 2HCl → MgCl2 + H2↑
n(Mg) = 7.2/24 = 0.3 моль
По уравнению реакции n(H2) = n(Mg) = 0.3 моль
V(H2) = 0.3*22.4 = 6.72 л