How does a system at equilibrium respond to a stress?

It shifts towards the side that is favored. So in equation A+B->C + D. If more A is added when its already at equillibrium, the forward reaction is favoured, it wants to use up the "A". Google Chatelier's principle on equillibrium. There are alot of factors that can cause stress

Olá. porque a reação na temperatura é muito rapida a do copo : )