In chemistry class, Allen determined the effectiveness of various metals in releasing hydrogen gas from hydrochloric acid. Several weeks later, Allen read that a utilities company was burying lead next to iron pipes to prevent rusting. Allen hypothesized that less rusting would occur with the more active metals. He placed the following into 4 separate beakers of water: (a) 1 iron nail, (b) 1 iron nail wrapped with an aluminum strip, (c) 1 iron nail wrapped with a magnesium strip, and (d) 1 iron nail wrapped with a lead strip. He used the same amount of water, equal amounts (mass) of the metals, and the same type of iron nails. At the end of 5 days, he rated the amount of rusting as small, moderate, or large. He also recorded the color of the water.

Question

In chemistry class, Allen determined the effectiveness of various metals in releasing hydrogen gas from hydrochloric acid. Several weeks later, Allen read that a utilities company was burying lead next to iron pipes to prevent rusting. Allen hypothesized that less rusting would occur with the more active metals. He placed the following into 4 separate beakers of water: (a) 1 iron nail, (b) 1 iron nail wrapped with an aluminum strip, (c) 1 iron nail wrapped with a magnesium strip, and (d) 1 iron nail wrapped with a lead strip. He used the same amount of water, equal amounts (mass) of the metals, and the same type of iron nails. At the end of 5 days, he rated the amount of rusting as small, moderate, or large. He also recorded the color of the water.

5. Is there a control for this experiment? If so, what is it?
6. What are two constants for this experiment?

Answer 1

5. In this experiment, the control would be the beaker containing just the iron nail without any additional metals wrapped around it. This allows Allen to compare the amount of rusting in the other beakers to the expected level of rusting in the absence of any additional metals.

6. Two constants for this experiment are the amount of water used in each beaker and the type of iron nails used. By keeping these factors constant, Allen ensures that any differences in rusting can be attributed to the variable being tested, which is the different metals wrapped around the iron nails.

Answer 2

5. In this experiment, the control would be the beaker containing only the iron nail without any additional metals wrapped around it. This allows for comparison to see the difference in rusting between the iron nail and the iron nails wrapped with different metals.

6. Two constants for this experiment are:
- The type of iron nails used: The same type of iron nails should be used in all four beakers to ensure consistency and eliminate any variation that could arise from using different types of iron nails.
- The amount of water used: Equal amounts of water should be used in all four beakers to ensure that the only variable being tested is the effect of the different metals on rusting. This way, any difference in rusting can be attributed to the presence or absence of the additional metals and not the amount of water present.