Be aware that, while one is active voice and the other passive, they are also different tenses. I scalded my tongue with hot tea - past tense, happened one time. My tongue is scalded with hot tea - present tense, happens regularly (so a weird thing to say).

Yes they are both acceptable as one of them is active and one is passive!

"I scalded my tongue with hot tea" is the active voice. The second sentence is passive voice. The meaning is the same, but most people prefer the active voice. Especially in writing. Why? It is clearer and easier to understand. In this case, we may use the second sentence if the focus is on the burn in your mouth, and less on the action itself.