Chemistry is a branch of science that studies chemicals/. It is interesting to predict which reaction will produce what. It can be confusing in the start but once you know what is going to happen, it becomes immensely easy for you. There are also certain formulations that describe how the reaction will proceed. For instance a metal when reacts with an acid produces hydrogen gas and salt.
Hence, when copper reacts with sulphuric acid, it causes the production of copper sulphate and hydrogen gas. The copper sulphate has a blue color and may precipitate at the bottom of the flask.
