Introduction

    Let's conduct a simple experiment. This is simple for us, but for scientists in France in the late eighteenth century it was much more difficult.  This experiment had profound consequences and led to one of the most fundamental laws of chemistry.
First, let's weigh a piece of magnesium ribbon and then weigh a match. Next, we'll strike the match and use it to light the magnesium ribbon. Finally, we'll weigh the burnt match and the product of the burned magnesium ribbon. What do you think the results are?


I think the magnesium ribbongains orloses mass.
And I think the match gains loses mass

The Frenchman Antoine Lavoisier was one of the first to do experiments of this kind. Much to his surprise, he found that the magnesium ribbon gained mass.

Since matches were not invented in Lavoiser's time, he could not have found out about the mass of the match. However, you can. And you would find that the match loses mass. What's going on here? How can we understand these results?