1. Enzyme Lab
Post-Lab

2. 1. Define catalyst
A chemical that speeds up the rate of a reaction without being used up or destroyed

3. 2. How are enzymes & catalysts similar? Different?
They both speed up reaction rates without being destroyed (same function)
Enzymes are proteins produced by living cells whereas catalysts can be any chemical that speeds up reaction rates (a catalyst does not have to be a protein)

4. 3. What substance used in Part 1 is a catalyst?
Manganese dioxide

5. 4. What source of enzyme gave a better reaction -- liver or potato? Why?
The liver
Liver contains more heme, which is attached to the protein part of catalase

6. 5a. In Part 3, what are you really adding when you add more liver?
More enzyme (catalase)

7. 5b. Why does the reaction turn out as it did when more liver is added?
Nothing happened when fresh liver was added to the test tube because the peroxide was already broken down - there was nothing for the enzyme to act upon

8. 5c. What happens when more peroxide is added to the old liver + liquid?
A reaction occurred - the enzymes in the old liver broke down the fresh peroxide

9. 5d. What do the results of this part of the experiment tell you about enzymes & how they react?
An enzyme is not used up or destroyed during a reaction - it can be used over and over again

10. 6a. How does the reaction rate in Part 4 differ with that in Part 2 for potato? For liver?
The reaction rate is faster in Part 4 for both the potato & the liver

11. 6b. Explain why.
This is because the smaller (crushed) pieces have a greater surface area of enzyme exposed to the peroxide = faster reaction rates

12. 7a. What general statement can you make about reaction rates & temperature?
For this reaction, the warmer the temperature, the faster the reaction rate (up to a point)

13. 7b. What does kinetic energy have to do with this?
Kinetic energy is the energy of motion- the increased temperature causes the molecules to move faster & interact with each other more quickly

14. 7c. What was your predicted reaction rate for 100 degrees Celsius
varies

15. 7d. Did you results support your prediction? Explain.
Varies
Varies; too much heat will denature (change the shape) of an enzyme, making it useless

16. 8a. What is pH a measure of?
How acidic (lots of H+ ions) or basic (lots of OH- ions) a substance is

17. 8b. Which pH conditions reacted poorly?
NaOH (basic) and HCl (acidic)

18. 8c. Under what conditions did the enzyme work well?
Neutral (water)

19. 8d. Would you say that enzymes are specific or nonspecific about the pH of the environment in which they must function?
Specific - catalase only worked well
under neutral conditions

20. 9a. What temperature change occurs in the tube for Part 7?
The temperature increases

21. 9b. What caused this change?
The chemical reaction gave off heat

22. 9c. Would you say that the reaction of catalase and hydrogen peroxide is an endothermic or exothermic reaction?
Exothermic

23. 10a. Which gas is given off during this reaction?
oxygen

24. 10b. Why do you think so?
The glowing splint flared up (burned brighter)

25. 10c. What substance is left in the test tube after the breakdown of hydrogen peroxide?
Water (H2O)

26. 10d. Write a balanced equation for this reaction.
(catalase)
2H > 2H O2