Translate
Introduction to Mass Balances
Use basic accounting to track chemical inputs and outputs.
What Goes In Must Come Out
Mass balance is the chemical engineer's version of a bank account. Just as you track money entering and leaving your account, engineers track the mass of substances entering and leaving a process unit.
The Law of Conservation
At the heart of a mass balance is the law of conservation of mass: matter is neither created nor destroyed. If you feed 10 kilograms of raw materials into a reactor, you must account for 10 kilograms of output, whether it ends up in the final product, waste, or byproduct streams.
Steady State vs. Dynamic
In a steady-state system, the mass flow remains constant over time. This makes calculations straightforward. However, many systems are dynamic, meaning they change during startup or shutdown. By mastering mass balances, engineers ensure that plants run safely and efficiently, minimizing waste and ensuring that expensive raw materials are utilized effectively in the final product.
Try this at home
Perform a kitchen mass balance. Weigh a bowl of dry ingredients (flour, sugar, etc.) before mixing. Add a specific amount of liquid (water, milk). Weigh the total mixture. Then, pour the mixture into a pan and bake it. Weigh the final bread product. The loss in weight is the mass of water that evaporated during baking. By weighing your inputs and outputs, you have performed a basic chemical process mass balance, accounting for the 'lost' mass through the steam produced during cooking.
