Famous iodine clock reaction: oxidation of potassium iodide by hydrogen peroxide. Mixture A: - 10 mL 2.0 M sulphuric acid - 10 mL 3% hydrogen peroxide - 80 mL water Mixture B: - Solution of 0.04 g sodium thiosulfate pentahydrate in 20 mL water - Solution of 0.9 g potassium iodide in 5 mL water - 4 mL starch solution - 71 mL water
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This experiment demonstrates the iodine clock reaction between iodide and persulfate ions, using thiosulfate as the 'clock'. After some introduction details, three experiments are performed: studying the effect of concentration to determine the orders of reactants (3:01), studying the effect of temperature to determine the activation energy (7:47) and studying the effect of solvent polarity (9:42).
Views: 40874 Michael Seery
Photosynthesis. Do you know how plants make their own food? Plants prepare their own food by a process called photosynthesis. Photo is the Greek word for light and synthesis is the Greek word for putting together. Plants need sunlight, carbon dioxide from air and water from soil to prepare their own food. Photosynthesis takes place in the leaves of a plant. Leaves have tiny pores called stomata through which carbon dioxide enters the plant. Plant cells contains tiny structures called chloroplasts that contain chlorophyll. Carbon dioxide and water, in the presence of sunlight and chlorophyll get converted into glucose and oxygen. Oxygen then leaves the plant through the stomata. Glucose gives nourishment to the plant. The extra glucose produced is stored by the plant in the form of starch for later use. Photosynthesis is the process by which plants prepare their own food using carbon dioxide and water in the presence of sunlight.
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