← Back to course
Matter Lab 6-8 / Week 07 / Bench Day
6/6
Week 07 · Physical Change or Chemical Change?

Bench Day

Bench Day: Change hunt
// Same stuff in a new form, or something new?
⏱ about 20 min

Bench Day: Change Hunt

Saturday morning, Rocket tapes a sheet of paper to the fridge. Two columns: physical and chemical.

"Everyone adds one change before lunch," he says. "Winner gets to pick the next Bench Lab."

Raven adds "toast browning" to the chemical side. "What do you notice?" she asks. "The bread changed color and got stiff."

Rocket writes "ice in the freezer" under physical. Nova hovers by the sheet, reading. "One of these needs a second look," she says.

Someone has written "sugar in warm water" under chemical. Rocket stares at it. "The sugar is still sugar. That goes on the other side."

Raven crosses it out gently and moves it. "Mistakes are how the list gets better," she says.

  1. A physical property can be measured without changing what the substance is. Melting point, boiling point and density are examples.
  2. A physical change keeps the identity of the matter. Melting, freezing, boiling, condensing and dissolving are physical changes.
  3. A chemical change, or chemical reaction, makes one or more new substances with different properties.
  4. Four clues suggest a reaction: color change, gas produced, precipitate, energy transfer. Only a property check proves it.
  5. Baking soda and vinegar react and produce carbon dioxide gas, a new substance.
◇ FAMILY CHANGE HUNT
Tape a sheet with two columns, physical and chemical, somewhere everyone passes.
Each person adds at least two changes seen around the home today. Toast, ice, a wet towel drying, a cooked egg.
At the end of the day, read the list together. For each one, name the clue and ask: is the stuff at the end the same stuff?
Move anything that landed in the wrong column, and say why. Moving one is a win for the whole list.
For a grown-up
The change hunt is observation only. Nobody heats, burns or mixes anything new today.
If the family wants to repeat Wednesday's cups, safety glasses go on and the cups stay on a tray.
This week's definitions come from the CK-12 chemistry text at chem.libretexts.org and the NIST Chemistry WebBook at webbook.nist.gov.
Safety first
Nothing is tasted or smelled up close during the hunt.
A grown-up handles anything hot, such as the toaster or the kettle.
SORT THE HUNT
  • Read the question.
  • Tap your answer.
A wet towel dries on a hook. Which column?
Toast turns brown and stiff. Which column?
Someone wrote "sugar in warm water" under chemical. Where does it belong?
Baking soda and vinegar react to make which gas? Type two words, or just the first.
WHY THIS EXERCISENext week you will weigh this gas without letting it escape.
Draw your family's two-column sheet with at least six changes on it. Circle the clue for each chemical change.
← Friday