Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


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Answers:
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  1. What does endothermic mean? (a) the study of bugs (b) when a chemical reaction gives off heat (c) when a chemical reaction absorbs heat (d) the study of chemical reactions
  2. Why does red cabbage work to indicate acid or bases? Red cabbage contains a naturally occurring indicator, anthocyanin. Anthocyanin is what gives leaves, stems, fruits, and flowers their colors.
  3. Where can you find acetic acid in your house right now? In the cabinet in a bottle labeled ‘distilled white vinegar’.
  4. Turmeric needs to be mixed with what before it can be used as an indicator? (a) hydrogen peroxide (b) rubbing alcohol (c) acetic acid (d) cold water
  5. When the red cabbage indicator is added to acetic acid, it turns (a) pink (b) blue (c) green (d) purple (e) yellow
  6. What happens when you heat up your cobalt chloride painting? A concentrated solution of cobalt chloride is red at room temperature, blue when heated, and pale-to-clear when frozen.
  7. In the electrolysis experiment, which gas gives you the “POP!” ? (a) hydrogen (b) oxygen (c) nitrogen (d) sulfur hexafluoride
  8. If you splash chemicals in your eyes, what is the first thing you should do? (a) put on your safety goggles (b) scream (c) rinse with running water, like from the sink or hose (d) call poison control
  9. If your dog accidentally eats your chemicals, what should you do? (a) lock him up (b) take him to the vet (c) call poison control (d) palpate his abdomen
  10. Which of these are chemical changes? (a) setting a wad of paper on fire (b) chewing gum (c) eating raisins (d) initializing a cold pack
  11. Which of these are physical changes? (a) light sticks (b) splashing in a puddle (c) drinking water (d) making slime

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Comments

2 Responses to “Answers to ‘Molecules’ Exercises”

  1. Good question! Physical change would be your teeth grinding the food down, but a chemical change happens in the stomach when the strong acids combine with the food to break it down. Your body does a chemical change on the food, but your mouth does the physical change to get it into the right shape to fit down your throat. Does that help?

  2. Lynn Woitalla says:

    Question by Jacob:

    RE: Chemical vs. Physical changes

    Some things are obviously chemical or physical changes. But what about eating? Chewing food would just be a physical change – it’s just breaking the food into smaller pieces of the same thing. But what about the process of digesting food? Doesn’t food change as your body processes it? As the body breaks food down, it there any chemical reaction taking place or is it all physical??