When there are explosions in movies they use a powder, but what is the name of the powder that is used for the explosions? What is the chemical name?

During the scene where Ana (Malcom's widow) is selling an engagement ring. I first watched this move in the summer of 2000 when I turned 8. Then and now I felt that she was selling her own engagement despite it her owning an antique shop. The couple that came in, the female fiancee asked "does he...