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Conduct step-by-step chemical change experiments using CuSO4, ammonia, and HCl with detailed instructions and observations. Learn about signs of chemical changes and how to handle different substances safely.
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Chemical Change Labettini MATERIALS: • Goggles & aprons • Squeeze bottles: CuSO4, Ammonia, HCl • Foil strip • Test tube, rack & tongs • Burner • Disposal cup
Chemical Change Labettini PRE-LABETTINI NOTES: TEST TUBES — Keep test tubes in rack, although you may lift the tube carefully after each step to get a better look at the contents and to CAREFULLY feel if the tube us 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 1 ml of CuSO4 to test tube. Observe color & consistency. STEP 2: Add 1 drop of ammonia. Do not shake the test tube! Observe signs of chemical change. After observations, shake test tube gently to distribute the precipitate evenly. STEP 3: GENTLY add 10 drops of ammonia. 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 signs of chemical change. After, pour gray-black liquid into disposal cup, but leave the crud (precipitate) in test tube. STEP 5: Add 10 drops of hydrochloric acid. CAREFULLY tilt and roll the test tube to react all the residue. DO NOT BREATHE THE FUMES. 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 signs of chemical change. CLEAN UP: Dump test tube into disposal cup. Dump disposal cup in orange waste bucket. Rinse grad cylinder, test tube 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 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 + H2O1 Cu, 2 O, 2 H on each side (3 pt) 9 pt total
