I2->HI->HgI2->HgBr2->MgBr2->AgBr
H2+I2 = 2 HI
Hg + 2 HI = HgI2 + 2 H
HgI2+2 KBr = HgBr2+2 KI
Mg + HgBr2 = MgBr2 + Hg
MgBr2 + 2 Ag = 2 AgBr + Mg
I2->HI->HgI2->HgBr2->MgBr2->AgBr
H2+I2 = 2 HI
Hg + 2 HI = HgI2 + 2 H
HgI2+2 KBr = HgBr2+2 KI
Mg + HgBr2 = MgBr2 + Hg
MgBr2 + 2 Ag = 2 AgBr + Mg