Even scientists need a break sometimes! When I take a break, I like to relax with a cool drink. But something strange happened today. I left a glass full of water on the table, and when I came back, it was only half-full. Where did the water go? Did it just disappear? Let’s find out!
You already know a lot about matter. Matter can change between different states like solids, liquids, and gases. It can also be part of mixtures called solutions. In solutions, the particles of matter spread out evenly, like sugar in sweet tea. When sugar dissolves in tea, it goes through a physical change. This means the sugar changes form but doesn’t become something new, and we can usually reverse it, like when we evaporate water to separate sugar from tea.
Matter can also go through chemical changes. This happens when particles rearrange to form a new substance, like when cake batter turns into a fluffy cake. Clues like gas bubbles and yummy smells show a chemical change is happening. Once a chemical change occurs, it can’t be undone. The process is called a chemical reaction, where the starting substances are reactants, and the new substance is the product.
One important thing about matter is that it can’t just appear or disappear. This is because of a scientific rule called the conservation of mass. It means that the amount of matter, or mass, stays the same. Scientists have tested this idea for hundreds of years, and it’s always true.
So, what happened to the water in my glass? It didn’t disappear. The water evaporated, meaning it turned into gas and mixed with the air. This is a physical change. The water is still there, just not visible.
Imagine you mix 5 grams of sugar into 10 grams of water. After stirring, the sugar seems to disappear, but it hasn’t. The total mass is still 15 grams. The sugar dissolved, a physical change, but if you could collect all the sugar, it would still weigh 5 grams.
The same idea applies to the water in my glass. If we could capture all the water molecules that evaporated and weigh them with the remaining water, it would equal the original amount.
The conservation of mass tells us that matter is never created or lost; it just changes form. We saw this with physical changes, like sugar dissolving, and it also applies to chemical changes, where new substances are made. But that’s a story for another day. See you next time!
