If you are salaried, can an employer expect you to work a 10 hour plus day while only being paid for an 8 hour day?

Typically, a salaried employee is considered to be "exempt" (i.e. someone who is exempt from overtime and related labor laws). And legally, there is no upper limit on how many hours a company can require an exempt employee to work.  However, just because an employee is salaried does not automatically make them exempt. Being paid on a salary basis is only part of the test for most forms of exemption but it's not the only requirement.  The fact is that it's possible to be salaried and still get overtime. And "non-exempt" employees must be paid overtime for hours worked over 40 in a week. 

On the other hand, if someone is an exempt employee then unless they have an employment contract, etc. that states otherwise, their employer may make them work unlimited hours and without overtime pay.

Without more facts of your employment duries it's hard to say whether you are exempt or non-exempt. As a rule professionals, adminstrators and/or managers are considered to be exempt employees. However a label of, for example, "manager" may not be enough in and of itself to establish an employee's legal status as exempt. Typically an exempt employee: is paid a salary; primarily performs on-site office duties and/or non-manual work duties; does not participate in sales or production, hires and/or supervises others, and the like.

At this point you can contact your state's department of labor or an employment law attorney for further information.