Science Buddies: "Ask an Expert"

Hi there,

Yesterday I did the experiment mentioned above (https://www.sciencebuddies.org/science- ... -corrosion). However, the temperature of the steel wool had no significant change. I don't know what the problem was since I did the experiment without changing it in any way. I read online, and there are two other reports of this experiment. One had the desired results, and another had the same results as I did-- no change in temperature.

One issue that may have been the reason why the experiment was a failure is that the steel wool was "trapped" inside of a test tube, allowing no oxygen to rust the wool. A potential solution might be to have the steel wool out in the open, although I have not attempted this yet due to my having to finish my science fair project.

However, I am not sure and would like some input on what may or may not have gone wrong.

Thank you!

P.S. I used finest-grade steel wool, fresh lemon juice, and a size 2 test tube/rubber stopper combo.

Hi junebugjasmine,

There could be several reasons for not observing a temperature change. One possibility, as you pointed out is insufficient oxygen in the test tube. Did you see any darkening or color change in the steel wool? Lack of any color change suggests that there was no rust formation. You might try again with a larger test tube or with a smaller amount of steel wool.

Did you wring most of the lemon juice out of the steel wool before assembling the thermometer/test tube apparatus? Excessive liquid could limit the change in temperature due to a “heat sink” effect.

Another possibility is that the thermometer was not in contact with the steel wool. You might put the thermometer into the steel wool, then cover the steel wool with your hand. Does the temperature increase? If so, you probably have good contact between the steel wool and thermometer.

Did you complete three trials of your experiment as described in the project procedure? If so, did any of the trials show a temperature change? Did you try the experiments with distilled water and an acid other than lemon juice? Did any of these show temperature changes? If you never saw any temperature changes perhaps your thermometer isn't working properly.

I hope this helps. Please ask again if you have more questions.

A. Norman