Is it possible for a woman to pass on syphilis to her newborn withiout passing it on to her mate?

Possible. Transmission of this disease to a fetus will occur if the germ enters the bloodstream of the mother which is most likely in the first 4 yrs of untreated disease. Transmission to a sexual partner requires contact with a contageous sore, seen or unseen, for germ passage. If the sores have healed before sexual contact, sexual transmission is less likely but many sores are unseen. Possible not likely.
It is possible. If the woman has tertiary syphilis. Hopefully no woman with untreated syphilis get pregnant. It is so easy to treat ; congenital syphilis is horrendous.