Lab - Light Chlorophyll and Photosyntheisis - Honors.doc -...

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Name _______________________ Class________________ The process of photosynthesis is one, which is extremely complex. Much experimental effort from the time of Joseph Priestly in 1771 has gone into determining the exact steps in the process. Practically all living things obtain their life energy from this important process. We are going to look at some of the major aspects of the photosynthetic process. This laboratory exercise is divided into six parts. Your teacher may select certain parts to demonstrate only certain sections. Photosynthesis and the Splitting of Water Photosynthesis occurs in two steps: 1. 12H 2 O + Light chlorophyll 24H + + 6O 2 2. 6CO 2 + 24H + enzymes C 6 H 12 O 6 + 6H 2 O Light is only necessary in the first step. As a result this step is logically called the light reaction. Since light is not necessary for the second step it is called the dark reaction. We can’t demonstrate adequately in this lab the light reaction. But we can demonstrate why this is important by using electricity to split water rather than light. The splitting of water using light is called photolysis; using electricity it is called electrolysis. MATERIALS: Hoffman electrolysis apparatus 6-10 volt DC source Concentrated sulfuric acid Wood splints Two test tubes Light, Chlorophyll, and Photosynthesis-HONORS Lab: Introduction: Part A: Method for Part A: RECORD AND NOTE OBSERVATIONS HERE:
Part A Questions: 1. When the current was turned on what happened in each tube? What does this mean is happening to water molecules? ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ 2. There are two electrodes in the apparatus (+) and (-). What is the approximate proportion of gas on the – side? Which side, + or -, has the hydrogen gas? ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ 3. When your instructor collected the gas and introduced a burning splint in each tube what happened? ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ 4. Which gas, hydrogen or oxygen, had the available stored energy? How do you know? ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ 5. How did the gas get this energy and how did you store it? Explain how the energy of sunlight is used in a similar fashion in the photosynthesis process.

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