1. Chemical Change Labettini
MATERIALS:
• Goggles & aprons; one glove (for HCl)
• Squeeze bottles: CuSO4 (#1), Ammonia, HCl
• Foil strip
• Test tube, rack & tongs, stir stick
• Burner
• Disposal cup

2. Chemical Change Labettini
PRE-LABETTINI NOTES:
TEST TUBES — Keep test tubes in rack when adding chemicals. You may lift the tube CAREFULLY after each step to get a better look at the contents and to CAREFULLY feel if the tube is hot or cold.
SQUEEZE BOTTLES — Hold by the collar until actually dispensing drops. Turn bottles upside down SLOWLY and only when tip of bottle is over the test tube.
NOTEBOOK — Title notebook section “Chemical Change Labettini”. Number steps 1-6. Record all observations.

3. Chemical Change Labettini
STEP 1:
Use 10-ml grad cylinder to add 2 ml of CuSO4 (Bottle #1) to test tube. Observe color & consistency.
STEP 2:
Add 2 drops of ammonia. Do not shake the test tube! Observe color & consistency. Observe signs of chemical change. After observations, shake test tube gently to distribute the precipitate evenly.
STEP 3:
GENTLY add 2 ml of ammonia. Observe color & consistency. Observe signs of chemical change. Observe signs of chemical change. After, shake test tube gently to react all of solution (should all be dark blue).

4. Chemical Change Labettini
STEP 4:
Heat test tube CAREFULLY and EVENLY over burner until it just starts to boil. Be careful not to overheat! Observe color & consistency. Observe signs of chemical change. Allow contents to settle and observe again.
After, pour gray-blue liquid into disposal cup, but leave the crud (precipitate) in test tube.

5. Chemical Change Labettini
STEP 5:
Add 10 drops of hydrochloric acid using a gloved hand! CAREFULLY tilt and roll the test tube to react all the residue. DO NOT BREATHE THE FUMES. Observe color & consistency. Observe signs of chemical change.

6. Chemical Change Labettini
STEP 6:
Get strip of foil from front table. Fold in half lengthwise. Put strip in test tube. DO NOT BREATHE THE FUMES. Observe color & consistency. Observe signs of chemical change.
At end, use stir stick to poke and mix until reaction is completed. Allow to settle and observe.
CLEAN UP:
Dump test tube into disposal cup. Dump disposal cup in orange waste bucket. Rinse grad cylinder, test tube, stir stick and cup at sink.

7. Chemical Change Labettini: Qs
What kind of mixture before and after heating?
Evidence of chemical change during heating
Cu(OH)2 + heat  CuO + H2O

8. Chemical Change Labettini: Qs
What kind of mixture before and after heating? Before heating mixture was homogeneous because it it was the same dark blue everywhere. After heating it was heterogeneous because there was a dark purple-black liquid and black sludge. (4 pts)
Evidence of chemical change during heating?
Cu(OH)2 + heat  CuO + H2O

9. Chemical Change Labettini: Qs
What kind of mixture before and after heating? Before heating mixture was homogeneous because it it was the same dark blue everywhere. After heating it was heterogeneous because there was a dark purple-black liquid and black sludge.
Evidence of chemical change during heating (x2)? • Formation of precipitate (sludge) • Color change • Smell (2 pt)
Cu(OH)2 + heat  CuO + H2O
Reminder: Chemical changes change molecules, but CAN be undone with more chemistry!

10. Chemical Change Labettini: Qs
What kind of mixture before and after heating? Before heating mixture was homogeneous because it it was the same dark blue everywhere. After heating it was heterogeneous because there was a dark purple-black liquid and black sludge.
Evidence of chemical change during heating? • Formation of precipitate (sludge) • Color change • Smell
Cu(OH)2 + heat  CuO + H2O 1 Cu, 2 O, 2 H on each side (3 pt).
9 pt total
Note: Copper hydroxide destroyed! Copper oxide & water made! Molecules changed! Atoms same!