How long does it take for a 2nd degree nitric acid burn?

My baby is 1 yr 2 months old and my father use a nitric acid to check for gold purity as we run a pawn broker shop! My baby accidentally took a bottle of nitric acid and spilled over him ! It was 1st degree burn on his hand and foot but in his stomach the burn is severe and it bleeds while remove dressing! How long does it take for a chemical burn to heal and is there any ointment to fade scar ? Kindly someone help