When something bad happens and you remain “impassive” what you are doing is keeping a wooden face. You are not displaying an emotion of any kind. It could be you do not feel any emotion, or you have chosen to hide it. The heroes in many of our movies remain impassive in all situations. They are the strong silent men who remain unmoved.
*After killing the man with his knife, the hero looked on impassively at the sea.
“Impassioned”, on the other hand, means someone who is “full of passion”, an individual who displays intense feeling about something or someone.
*The impassioned speech by the Vice-Chancellor brought the audience to its feet.