EXPERIMENTAL: AN INVESTIGATION OF SOME OF THE VARIABLES INVOLVED IN THE DECOMPOSITION OF AQUEOUS HYDROGEN PEROXIDE
Introduction Hydrogen peroxide is a toxic excretion product from certain metabolic reactions in living cells; accordingly, its removal is essential to ensure survival of a living cell or an organism.
Aqueous hydrogen peroxide decomposes slowly at ambient temperatures, but published studies have shown that its decomposition is speeded up by the enzyme catalase and by various inorganic catalysts [such as manganese(IV) oxide]: Catalase or MnO2 2H2O2(aq) 覧覧覧覧覧覧覧覧ｮ 2H2O(l) + O2(g)
In this investigation, you are required to examine at least three variables involved in the decomposition of aqueous hydrogen peroxide; at least two of these must be quantitative.
Notes 1. Each enzyme is assigned a numerical classification (as approved by the international scientific organizations); catalase, for example, is E.C. (Enzyme Commission) 220.127.116.11.
2. Despite differences in size and complexity, all living organisms show remarkable similarity in biochemical reactions; and so, as might be expected, catalase is present in most of these organisms. However, extraction of the pure enzyme is tedious - so most investigations use convenient sources (e.g., liver, potato, or yeast).
3. Apart from your notes and standard textbooks, sources of scientific knowledge include encyclopaedias in libraries, on CD-ROMs, and on the Web; it is good practice to include a bibliography in your write-up.
4. You are provided with 30% aqueous hydrogen peroxide, sources of the enzyme catalase (e.g., potato), a variety of inorganic substances, and distilled water. In addition, you will need to use - within reason - suitable apparatus.
5. The proposed plans of your investigation should be presented in detail; these plans may be modified as the investigation proceeds.
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