HBr=H(+)+Br(-)
Ca(OH)2=Ca(+2)+2OH(-)
Mg(NO3)2=Mg(+2)+2NO3(-)
m(Mg)=1.2г
V(H2)=
Mr (h2)=2
Mg+H2O=MgO+H2
24 2
1.2 X
X=1.2*2/24=0.1
V(H2)=0.1/2=0.05
KOH => K(+) + OH(-)
C(KOH) = C(OH - ) = 0,025 М
[H+] = Kд/[OH-] = 10^(-14) / 0,025 = 4 * 10^(-13)
pH = - lg[H+] = 12,4
Ответ: 12,4
H2SO4+2NaOH=>Na2SO4 + 2H2O