About This Lab
In this lab, you will examine the effects of temperature, pH, and substrate concentration on the enzyme, catalase. Catalase greatly accelerates the decomposition of dangerously reactive hydrogen peroxide into harmless water, oxygen, and heat as shown in the equation below.
Because oxygen gas is created as a product, the rate of the reaction is easy to evaluate by looking at how many and how quickly gas bubbles are produced.
Most living cells contain catalase because many cellular reactions form hydrogen peroxide as a product. Mammalian liver has a high concentration of catalase and is the source of the catalase used in this lab.
*If the experiment were to use the same catalase but change the chemical from hydrogen peroxide to hydrogen per sulfide (H2S2), would the experiment have better or worse results. Remember that sulfur is in the same period as oxygen, but heavier and larger with a lower electronegativity. Explain your answer.
In the solution containing hydrogen peroxide, your lab partner adds orange juice, which contains Vitamin C (ascorbic acid) just out of curiosity. Do the kinetics of enzyme catalysis change? If so, how?
In case of the following reaction, the breakage of O-O bond of hydrogen peroxide (to form water and oxygen) is favorable, which is not the case for the breakage of S-S bond of hydrogen persulfide (to form hydrogen sulfide and sulfur).
i.e. The breakage of S-S bond in hydrogen persulfide is not favorable.
Explanation: The sulfur has less electronegativity than the oxygen and heavier than oxygen. As a result, you need more energy to break S-S bond. The important bond energies are mentioned below.
O-O bond energy = 138 KJ/mol
S-S bond energy = 213 KJ/mol
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