Answer:
Step-by-step explanation:
Perform an experiment is a closed system (nothing can escape).
For example AgNO3 is soluble in water. So is NaCl
Put 10 grams of AgNO3 in 100 grams of water. Stir well.
Put 10 grams of NaCl in 100 grams of water.
Weigh the two containers to get the total mass. Weight them together.
Let's say you get 300 grams all together. (The beakers weigh something).
Now mix the two together. Weigh everything again including the empty beaker.
Everything should weigh what it did before, but you notice there is a white mass at the bottom that wasn't there before. There was a reaction, but no loss of mass.