A Simple Experiment Misinterpreted: Properties of Liquid vs Frozen Water

I’m taking a bit of a tangent from my usual subject material to have a bit of fun with some material that I recently found as part of this thing called the blogosphere.  Ok, maybe not all fun since I’m not sure if this post will make you laugh or cry or maybe both.    My WordPress tag browser led me to a short blog post several months ago, which I will review below, that made me scratch my head a bit. Was this a creation science parody blog or was the author of this site really serious? I have better things to do with my time but I had seen this blog (Already Answered) referenced on several other creation science blogs and sites and curiosity got the better of me and so I had to dig a little deeper.  What I discovered is that the author of the blog is serious in his evangelical fervor for promoting creation science.  Unfortunately that fervor doesn’t translate into a particularly accurate accounting  or reliable interpretation of evidence.

Let get to the article entitled simply:  Ice Expansion. It is very short and I will provide some of the most interesting parts:

A majority of you reading this article can remember learning about the molecules that make up gas, liquids and solids. Maybe it was last year or maybe in a fun little children’s book, or maybe you are learning about this for the first time.

Basically, when you have water you have these atoms identified as H2O. That means you have one oxygen atom connected to two hydrogen atoms. This is a basic structure. Well, water, as a liquid, has weak hydrogen bonds between itself and the other atoms (one drop of water can contain 6X1021atoms). That means that the hydrogen atoms connected to the oxygen atoms are being attracted to each other. This creates a structure for water.

Water molecules are attracted to one another by the polarity (negative/positive ends) of the water molecules. Ice forms when the molecular motion slows enough that the hydrogen bonds are maintained rather than constantly breaking as they are in liquid water.

I understand that the author is writing to a lay audience and so he is simplifying  the matter but I can’t help but get the feeling he doesn’t fully understand the basic chemistry himself.  However, lets continue and find out..

However, as the temperature of the water drops these atoms are attracted to each other with more intensity. So, as these atoms begin to come together they form a certain structure. Because of this the water becomes a solid.

But, when the ice starts to thaw something happens. The atoms start moving away from each other and decide to go back into their former shape. Of course, this will make the ice/water to expand since the atoms are splitting apart. It is for this reason that we get to do a experiment that has both fun and scientific value.

This seems logical on the face of it.  If thawing of ice results in the water molecules moving away from each other than it would follow that water must expand when ice melts.    As an aside, the atoms aren’t “splitting apart” that would be a nuclear fission reaction, rather the water molecules (H2O) are disconnecting because the hydrogen bonding of the individual molecules is not holding them together.

What followed this was a description of a proposed experiment you could do with your kids which goes something like this:  fill a water bottle with water and cap it tightly and then put it in the freezer.  Come back the next day and let it thaw  part way without opening it.  Now the following instructions:

Now, when you have let the bottle thaw for 1-2 hours give it to a friend or sibling that has a good sense of humor. Acting very scientific like, ask the person to open the bottle quickly. A couple tablespoons or more will spray/pour out of the bottle.

If the person keeps a steady hand you will be able to see that the water will still be at the very top of the water bottle.

Although your friend or sibling may get a little wet, you will have learned a lesson that when ice thaws it actually expands. Quite amazing!

The author uses this photo from Wikipedia to illustrate his page. I wonder if he thought about why the iceberg floats? If water expands when it melts should it become less dense than the ice? In which case shouldn’t that iceberg be sinking?

I wonder if you are thinking what I’m thinking!  Has this person actually performed this experiment?  Is the lesson to be learned really that when ice thaws it actually expands? I had to ask myself several times, do I just not remember my high school chemistry at all or is something very very wrong here?   I was even more confused because the title of the post was  “Ice Expansion” which suggested to me the opposite of what he concludes.  The problem isn’t just that his lesson to be learned is exactly OPPOSITE what happens to ice when it melts but the entire experiment is flawed.    Just think for a moment about the directions.   If water is placed in a bottle and capped and frozen then if he is right the water should shrink when frozen (if it expands when it melts it must have shrunk when it froze, at least that is what I would reason).    So, if it shrinks when it freezes then when it melts it should just expand back into the space it occupied before it shrank.   Why then would the bottle spray water when opened if the same amount of water is there in the same volume as when it started?  In fact, if it is only partially thawed, shouldn’t the bottle have less volume rather than more in which case when the cap is removed air should  be pulled into the bottle?

Strangely, the outcome that he predicts for this experience is actually what will happen!  Yes, water will actually squirt out to the bottle but NOT for the reason he says.  Here is what will happen that will lead to exactly the result that he predicts. If ice in fact expands when it freezes,  which is what I believe happens and every chemist I know believes happens, then the water in the bottle will expand pushing out on the bottle walls (especially since he says to use a plastic bottle) .  If a person only thaws the ice partially that pressure will still exist and so when someone opens the bottle water will spray out but NOT because the ice expands when it becomes liquid water but for the very opposite reason: the ice in the bottle expanded when it froze.   Interestingly, a person could come to the conclusion that it was the water expanding as it melted that caused the pressure in the bottle.  To maintain this conclusion though one would have to perform this experiment in this way and not know about all other experiments or other evidence (even other evidence that should come from this very experiment – see below).    The image he used on his page suggests he didn’t think through the other evidences of what happens to water when it freezes.  With a bit of thought he should realize that the image he provides on the blog refutes the very point he is trying to make:-)

Is there any lesson to be learned from this?

I think there is.  After getting over my initial shocked reaction after reading this article, I started to realize that the experiment the author describes actually illustrates some interesting aspects of the scientific method.   I may use this experiment as a thought exercise in my introductory biology class in the future asking them to critique the hypotheses, conclusions and predictions of the experiment.  I might ask them to suggest how they could make the experiment better or devise a second experiment to test the results of the first.   The author clearly doesn’t have a lot of experience actually doing science and he certainly should have learned about water and ice many times in high school and college if he has such training.    His inability to remember the basic chemistry of water molecules though is not that shocking and he applied a certain logic in this experiment which was not altogether flawed.   As I said before, if you actually performed this experiment you might draw the same conclusion he did: ice expands when it melts.  But to do so you would have to ignore a lot of observations/evidence and be fixated on only one observation (water spraying out of the bottle)    The problem is that this one experiment is not the end of the story.   One needs to examine more variables with more tests before drawing this conclusion.  What if someone didn’t let the bottle partially thaw but let it thaw all the way, would they conclude that ice expands?  Not at all, because the bottle would not spray water when opened.   I wonder, with closer observation would the author have noticed that the frozen bottle was actually larger than that the non-frozen bottle?  His conclusion leads one to the correlate that freezing water contracts (takes up less volume) and thus a prediction of his hypothesis should have been that the bottle would shrink when frozen.    Only by ignoring all the other data available to the observer could he really expect that the lesson to learn was the expansion of melting ice.

Sometimes a little bit of knowledge is a dangerous thing.  This author probably remembered doing an experiment with water and bottles in a class and then applied some ideas of chemistry that he remembered but completely confused the meaning of the results.   He probably remembers the general rule that molecules in motion take up more space than molecules that have slower motion.  Think of a hot air balloon, hot air pushes out and takes more space than cold air which shrinks in volume.  He is just transporting those basic gas laws and applying them to water.  However, water is one of the exceptions, we know this because of lots of experimentation including experiments just like the one he describes. In fact he probably did this experiment when he was young as a demonstration that water does expand when it freezes.    What happens is water molecules do contract slighting as they get colder in a liquid state but when they freeze they form a crystal lattice structure that has more space between molecules of water than when they were in the liquid state and thus the ice crystals formed take up more space (volume) than the equivalent number of water molecules in a liquid state.   This is why ice floats on liquid water – it is less dense.  Water in gas state and liquid state do behave as expected – water liquid takes up much less volume than the same number of molecules in gaseous state.   So general rules are important to know but experimentation is important to test how those rules apply in particular circumstances.

Here we see a an example of ice crystals protruding from the mud. This picture is from the blog: Rebecca in the Woods (http://rebeccainthewoods.wordpress.com/tag/needle-ice/). What has happened here is that the water in the mud has frozen in the evening and because it expanded when it froze it had not were to go but get pushed up out of the mud. The ice is not “muddy” because when the water molecules form crystals they exclude other molecules in their lattice structure. Another example of this is sea ice, it comes from sea water which has lots of salt but the ice crystals themselves are nearly pure H20.

The broader context

I didn’t originally intend to write about this on my blog.  I realize that blogs can be one of least trustworthy sources of information because anyone can pretend to be an expert.  It wasn’t until I saw another creation science blogs reference to this blog that I thought it would only be fair to point out the problem with this post.   Still, I planned to simply write the author of this blog and let him know about his mistake on this particular post but there is no comment section and no ability to get feedback to the author that I can tell.   Hopefully he gets a trackback notification (update: he did, see comment section) from this post and removes this particularly unfortunate post.  I recognize this post is the result of an innocent mistake in understanding but the whole site is full of similar misconceptions about science and misinterpretations of data.   In general it appears to me that he has taken bad information from Answers in Genesis  (his professed favorite web site) and conflated that with his own misconceptions about science to produce an even worse product.   His blog very confidently proclaims the truths of how science confirms the Biblical creation.   I don’t believe his confidence is necessarily placed in his own abilities to interpret the data but rather his boldness in proclaiming the truths of science and the Bible are found in his belief that Answers in Genesis materials and their bold proclamations have provided him with the answers.  Here again, we are seeing another example of what I wrote about in a past post:   Having Faith in Flood Geology: Dogmatic Assertions of Evidence.

As an aside, the name of the blog is interesting: Already Answered.  The implication is that the Bible already has the answers we just need to find them there.   But the Bible doesn’t seem to have helped him with his understanding of water ice.   The Bible doesn’t comment on the density of ice and water and whether it expands or contracts.  However, we can explore God’s creation via the creative and reasoning capacities that God has endowed us with, allowing us to investigate his world and discover how it works.

Comments

  1. Hi Mr. Duff,

    Every once and awhile I come back and look at this article. I’m very glad you took the time to review it. I know I make mistakes on my site, and I appreciate the people who devote the time to expose them, in a loving manner of course!

    Maybe, this summer, you and I can have ourselves some email discussions once I graduate! Praying for you!

    In Christ Jesus alone,

    Jacob Howard

    http://www.uslds.org

    Like

  2. I want to thank the author of Already Answered for his very gracious reply to my post. I do wish him the best even if we may disagree one many things. I will modify my post when I get a chance to reflect a less skeptical tone.

    Like

Trackbacks

  1. […] So, last week I got some traffic from Naturalis Historia. This writer had found my science experiment on ice. Just so the writer can get a trackback and let him know I’m writing about what he wrote about me, I’m linking you guys to his article. […]

    Like

  2. […] I wrote a reply to Naturalis Historia’s critique of my article on ice expansion. Tomorrow, I will make the necessary changes to the article. I am […]

    Like

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