Name ______Period ______

Physical versus Chemical Changes Homework

Background:
A physical change simply means that you have rearranged the shape of the object. It can be characterized as tearing, wadding, rolling, stretching, flattening, or otherwise physically changing the shape, state of matter, or size without altering the chemical properties. If you wad up a piece of paper, you create a physical change. If you burn a piece of paper, you cause a chemical change You can identify a chemical change if there is a change in magnetism, there is heat produced or lost, and sometimes there is a color change.

(big picture) / (specifics)
Physical changes / The matter is the same.
The original matter can be recovered. / The particles of the substance are rearranged.
Chemical changes / The matter is different.
The old matter is no longer present. The original matter cannot be recovered. / The particles of the substance are broken apart, and the atoms are rearranged into new particles, forming a new substance.

Physical changes:

  • Wadding up a piece of paper
  • Chopping a piece of wood in half
  • Tearing piece of cloth
  • Cutting a hamburger with a knife
  • Biting into an apple
  • Flattening lump of clay with your hand
  • Hitting a baseball bat with a bat
  • Popping a balloon
  • Blowing bubbles out of a soap solution
  • Opening a piece of wrapped candy

Chemical changes:

  • Digesting your dinner
  • Removing grease with soap
  • Cooking an egg
  • Milk that has gone sour
  • Lighting a fire
  • Starting a car engine and burning gasoline
  • Putting acid in your sink to dissolve hairballs
  • Baking cookies
  • Taking an antacid tablet
  • Exercising (using sugars and fats stored in your body)

Write a “P” for physical change and a “C” for chemical change.

_____ 1. When baking soda is added to vinegar, bubbling occurs as carbon dioxide is formed.

_____ 2. Water evaporates from the ocean.

_____ 3. A piece of cloth is cut up into tiny bits.

_____ 4. Ice on a lake melts to become water in the lake.

_____ 5. Charcoal in a fire turns to ash after several hours.

_____ 6. A pencil is sharpened in a pencil sharpener, leaving behind shavings.

_____ 7. A battery makes electricity turn on a flashlight.

_____ 8. Nails left out in the rain for several weeks become rusty.

_____ 9. The yolk of an egg, which contains sulfur, causes tarnish to form on silver.

_____ 10. Aluminum foil is cut in half.

11.

The student inferred that a chemical reaction occurred. What two pieces of evidence support this inference?

______

______

12.

Fill in your answer in the grid 

13. List four signs of a chemical change:

  • ______
  • ______
  • ______
  • ______

14. Complete the table below:

Chemical Formula / Number of atoms of EACH element / # of atoms / # of elements / Compound? (y/n)
CaCl2 / Ca – 1 Cl – 2 / 3 / 2 / yes
AgNO3
2H2SO4
4HF
NH4NO3