Put simply, chemical engineering is the study of mass and energy transfer through systems. A better title would actually be ‘process engineering’ – a lot of chemical engineers work in companies where their role is to ensure that the system to make a product from raw materials works properly.
Chemical engineers take a process that chemists have come up with and then scale it up from a test tube to a factory. This is quite difficult as the system becomes more complicated as it gets bigger. It may be easy to heat chemicals in a test tube to a certain temperature, but this is much more difficult when you have millions of litres of the chemicals as the liquid in the middle won’t be at the same temperature as the liquid at the edge of the container.
We then have to add all the equipment to make sure that the process works correctly and safely. This includes valves, pumps, pipes, heat exchangers, level and temperature controls, and emergency systems. One chemical engineer can’t do all of this, so you usually find teams of us in companies with each person having a specialist role.