1) 2Mg + O2 = 2MgO
2) MgO + 2HCl = MgCl2 + H2O
2) MgCl2 + 2NaOH = 2NaCl + Mg(OH)2 ( осадок, стрелка вниз)
3) Mg(OH)2 + H2SO4 = MgSO4 + 2H2O
3Сa(OH)₂ + 2H₃PO₄ = Ca₃(PO₄)₂ + 6H₂O
3CaCl₂ + 2H₃PO₄ = Ca₃(PO₄)₂ + 6HCl
Mr(NaNO3)=23+14+3*16=85
W(Na)=23/85=0.27=27%
W(N)=14/85=0.16=16%
W(O3)=48/85=0.57=57%
Mr(FeCl3)=56+3*35.5=162.5
W(Fe)=56/162.5=0.35=35%
W(Cl)=106.5/162.5=0.65=65%
Mr(Pb(NO3)2)=207+2*14+6*16=331
W(Pb)=207/331=0.63=63%
W(N)=28/331=0.08=8%
W(O)=96/331=0.29=29%
А ................................