Yes it is. Blackmail is just asking for payment or for something in exchange for not exposing a person. Physical harm is not a requirement to prove blackmail. In ohio it is called extortion. The Ohio code is below. In some states it is called blakmail in others extortion.
(A) No person, with purpose to obtain any valuable thing or valuable benefit or to induce another to do an unlawful act, shall do any of the following:
(1) Threaten to commit any felony;
(2) Threaten to commit any offense of violence;
(3) Violate section 2903.21 or 2903.22 of the Revised Code;
(4) Utter or threaten any calumny against any person;
(5) Expose or threaten to expose any matter tending to subject any person to hatred, contempt, or ridicule, or to damage any person's personal or business repute, or to impair any person's credit.
(B) Whoever violates this section is guilty of extortion, a felony of the third degree.
(C) As used in this section, "threat" includes a direct threat and a threat by innuendo.