Chemical Changes Lab Questions

  1. Baking soda is NaHCO3. When mixed with HCl it forms carbon dioxide bubbles. Write the chemical formula for carbon dioxide (1 atom of carbon, 2 of oxygen). What consumer product contains carbon dioxide?
  2. In the other mixings, did any bubbles form?
  3. What do you think is the gas that results from the mixings in Question 2?
  4. Cells in your stomach produce hydrochloric acid (HCl), to help digest food. What color does blue food dye turn when HCl is added?
  5. Sodium hypochlorite, NaClO, is an ingredient in many household bleaches and cleansers. What happened to the color of the blue dye when both HCl and NaClO were added?
  6. Potassium iodide, KI, is the source of iodine in iodized salt. What color is the KI + NaClO mixture? What color does starch change to in the presence of KI and NaClO?
  7. A precipitate is a solid that forms and settles out when some solutions are mixed. Which reaction produced a very bright yellow precipitate?
  8. Which mixings produced precipitates? Describe their colors and appearance with words like milky, cloudy, grainy, etc.
  9. Which mixture produced a precipitate that was very slow to form?
  10. Which solutions produced a "muddy" brown precipitate?
  11. Observe the scrap of paper you used to absorb the AgNO3 + NH3 mixture. What evidence do you see that indicates that silver compounds are light sensitive?
  12. Review your results and list at least 3 different kinds of changes that indicate that a chemical reaction is occurring.
  13. Describe any other notable observations you made.