The rate of reaction that can be measured in the dark by determining the amount of oxygen gas consumed in a period of time is the rate of respiration.
Why?
Plants can undergo two types of reactions involving oxygen:
- <u>Photosynthesis: </u>In this type of reaction, plants use energy from light to synthesize glucose. The chemical reaction for photosynthesis is: 6H₂O + 6CO₂ → C₆H₁₂O₆ + 6O₂, and this reaction produces oxygen gas in the presence of light, that means that to measure the rate of photsynthesis, you'll need to measure the amount of oxgen gas <u>produced</u> in a period of time.
- <u>Respiration:</u> In this type of reaction, plants convert the energy stored in the chemical bonds of molecules such as glucose to obtain energy. The chemical reaction for respiration is: C₆H₁₂O + 6O₂ → 6H₂O + 6CO₂, since this reaction consumes oxygen gas in the dark, that means that to measure the rate of respiration, you'll need to measure the amount of oxygen gas <u>consumed</u> in a period of time.
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A hydrate is a substance where in it contains water and other constituent elements. To know whether if that compound was a hydrate,you should record its mass, then put it in a test tube and heat it with a Bunsen burner. If the compound is a hydrate, the water in the compound will discharge in the form of water vapor. At the next 5-10 minutes, remove it in the test tube and weigh it up again. If the mass is now fewer, that means that there was water existing that has now evaporated, and the compound was a hydrate.