We continue this new week by looking at another aspect of matter! This week we’re taking a look at the difference between chemical and physical changes: Physical changes in substances (matter) come in several forms. If we break glass or tear paper, we are changing the paper physically. If we were to then burn the torn paper, that would result in a chemical change where the bonds within the atoms of the paper are separated and new bonds are formed, thus changing the paper to carbon, smoke, ash, water vapor, etc. Other evidence of physical changes include: changes in phases (like melting ice to make a puddle of water, or freezing water to make ice) or size changes. Evidence for chemical changes include: formation of new substances, a temperature change from a chemical reaction, bubbles of gas, color changes, etc.
On Monday, we completed a lab which you were to find the type of unknow substance based on the evidence from tests you performed. You may have noticed some solids changed color, some had bubble release, while others had no change. You then used the evidence from the known substances to identify the unknown substance as Baking Powder (not flour! 🙂 )
Here were the follow up conclusion questions for your notebook:
1. What were 3 observations you made.
2. How did the Unknown substance react with the various liquids?
3. What is the unknown solid? And How do you know?
4. What evidence did you find for chemical changes versus physical changes?