SnCl2+HgCl2------>SnCl4+Hg2Cl2
SnCl2+2HgCl2--------------------->SnCl4+Hg2Cl2
Sn2+(-2e-)--------------------->Sn4+/1
Hg2+(+1e-)-------------------Hg1+/2
SnCl2+2HgCl2-----------------
SnCl2+2HgCl2--------------------->SnCl4+Hg2Cl2
Sn2+(-2e-)--------------------->Sn4+/1
Hg2+(+1e-)-------------------Hg1+/2