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Pre-AP Chemical Change Review & Energy Release Lab

Pre-AP Chemical Change Review & Energy Release Lab. October 24, 2011. Use the evidence below to support your claim of physical or chemical change. Physical vs. Chemical Change Lab. Physical Color changes (careful!) Substance is not changed, just size or shape Changing State Dissolving

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Pre-AP Chemical Change Review & Energy Release Lab

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  1. Pre-AP Chemical Change Review & Energy Release Lab October 24, 2011

  2. Use the evidence below to support your claim of physical or chemical change Physical vs. Chemical Change Lab • Physical • Color changes (careful!) • Substance is not changed, just size or shape • Changing State • Dissolving • Bending, Crushing, Mixing, Cutting, etc • Chemical • Color changes (careful!) • Forming a Gas (fizzing) • Foaming • Heat (endothermic/exothermic) • Production of sound, light or odor • Change CANNOT be undone Evidence:

  3. Observing Chemical Change

  4. Create Your Lab Write Up Title: A change in temperature? Guiding Question: How do I know a chemical change happened? (Leave a few lines here for your answer.)

  5. Create Your Lab Write Up Chart:

  6. Pre-AP Lab • You have three different powders in cups. • Write down your observations about the three powders. • Powder A- is NaHCO3 (Baking Soda) • Powder B- is Na2CO3 (Washing Soda) • Powder C- is C6H12O6 (Sugar)

  7. After you observe the materials • Add one scoop of Powder A to Plastic Bag A • Add one scoop of Powder B to Plastic Bag B • Add one scoop of Powder C to Plastic Bag C • Hypothesize what you think will happen when we add water to each of the Bags.

  8. Now add the Water • Add 10 mL of water to each Bag. • Observe and feel the Bags.

  9. Questions… 1. Was your hypothesis correct? 2. Which Bag(s) had a chemical reaction?

  10. Does baking soda lower water temperature? If so, why? • Baking soda is NaHCO3 and water is H2O added together you get NaOH and H2CO3 which are sodium hydroxide and carbonic acid. Carbonic acid is the fizz in soda. Eventually the mixture releases CO2 gas when the H2CO3 breaks down into H2O and CO2. The solution of H2O and CO2, if left alone uncorked, will lose its fizz. NaHCO3 + HOH ---> Na^+1 (aq) + OH^-1 (aq) + H2CO3 (aq) • Washing soda (Na2CO3) and water (H2O) added together form sodium ions and carbonate ions and water. Na2CO3 + H2O---> 2(Na+) + (CO3-2) + H2O

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