Take That Question With A Pinch Of Salt

(I am in a college level honors biology class. We’ve been discussing alkali metals, which are highly reactive elements like sodium and potassium.)

Student #1: “So if I put pure sodium and pure chlorine together, will it make salt?”

Professor: “Yes, but don’t ever do that. It would be a very dangerous and expensive way to make salt.”

Student #2: “If salt is so dangerous and expensive to make, why is it so cheap at the grocery store?”