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

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.

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).

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.

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.

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.

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

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

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!

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!