Question

Chicken liver is placed into lemon juice for 10 minutes. What type of evidence of a chemical reaction would be expected to occur when H2O2 (hydrogen peroxide) were added?
A) a lot of bubbles within a few seconds
B) some bubbles within the first minute
C) very few to no bubbles
D) the liver will catch fire, explote and cause the school to evacuate.

Answer 1

Answer:

When hydrogen peroxide is added to a chicken liver sample exposed to lemon juice the chemical reaction will be slower and appear some bubbles within the first minute (option B).

Explanation:

The liver contains an enzyme called catalase, whose function is the degradation of hydrogen peroxide (H₂O₂), an intense reaction that produces gas and heat. The activity of this enzyme must occur at an appropriate pH, so changes in pH can affect the activity of catalase.

• Under normal conditions, when a liver sample is exposed to H₂O₂, bubbles and foam appear in the sample as a result of the catalase reaction.
• When the chicken liver sample is subjected to the acidic lemon juice, the reaction will occur, but more slowly.

This is because the activity of the catalase enzyme, present in the liver, continues to occur —although it decreases— and will form few bubbles over a longer period of time.

The other options are not correct because:

    A. At a lower pH, the reaction will not form many bubbles.

    C. Even if the reaction is minor, and produces very few enzymes, it will always occur.

    D. Although the catalase/H2O2 reaction produces heat, it is impossible for the liver to catch fire and cause evacuation from the school, even less so with a reaction whose speed has been slowed down.