Will the credit card company charge interest on the balance transfer?

I have transferred the outstanding balance from my high interest credit card to a 0 percent interest balance transfer card. I have been making payments on the card for several months now. My intention is to pay off the balance within the introductory period. However, I have made a major mistake. I have purchased an appliance with the card. I want to pay off the balance before the credit card company charges any interest rate. Will the company charge an interest rate on the balance transfer or just on the appliance?