A few questions concerning photosynthesis experiments

  1. For the iodine test,
    How does boiling alcohol speed up the diffusion of chlorophyll out of the cells?
    Why does the leaf become crisp and breaks easily after it has been dehydrated by alcohol?

    For the detection of oxygen produced from photosynthesis,
    Why does sodium hydrogencarbonate solution decompose in water?
    How does the stoppers allow CO2 outside the funnel diffuse to the aquatic plant? (I really dont get it)

    For the investigation of the need for CO2 in photosynthesis,
    How does potassium hydroxide absorb CO2?
     
    Last edited: Apr 23, 2013
  2. jcsd
  3. Simon Bridge

    Simon Bridge 15,261
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    You should be able to answer those by considering what you already know about the properties of materials.

    i.e.
    Do some things dissolve better in alchohol than water?
    Does boiling generally extract pigments better than just soaking? (Think: red cabbage.)
    What happens to the leaves on plants, in general, all around you, when they get dry?
    Why would that be? What does a leaf do with the water it contains?
    etc.

    You have a question about dissolving, and another about a chemical reaction.
    You know that reactions happen.

    However - if you feel there is a lot of "magic black box" work in the school demo of photosynthesis, you are correct. You actually need lots more study to understand the proof. Right now you pretty much have to take the teachers word for what happens ... just like you have to take the teachers word that lime water goes cloudy when carbon-dioxide is bubbled through it.
     
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