Question Video: Identifying the Greater Contamination Risk Science

An amount of water has a radioactive gas dissolved in it. Which of the following would produce a greater contamination risk? [A] Freezing the water [B] Boiling the water

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Video Transcript

An amount of water has a radioactive gas dissolved in it. Which of the following would produce a greater contamination risk? (A) Freezing the water. (B) Boiling the water.

Okay, so here we have a container with this water in it. And we’re told that this water has a radioactive gas dissolved in it. Now, if the gas was really dissolved, the little pockets of gas would be so small we couldn’t see them. Here, we’ll represent this gas dissolved in the water using these dots. We want to know whether freezing this water or boiling it would produce a greater contamination risk. Let’s remember that contamination involves the mixing of substances together.

So, for example, if our water, with gas dissolved in it, were to mix with the air in the atmosphere, that would be contamination. Or if it mixed with — say, the soil in the ground — that would be contamination too. So, the way to decrease contamination risk is to make it hard for this water to mix with any other substance. We know if the water is frozen, it will become a solid object. That way, it will be relatively difficult for the block of ice to mix with any other substance.

But then, let’s think about boiling the water with the radioactive gas. In that case, everything in the water, including the radioactive gas, would be released into the atmosphere. Thanks to currents of air, this material could be spread long distances. So, while freezing the water contains contamination risk, boiling it makes it more likely that those water and radioactive gas will mix with other substances. We choose answer option (B).

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