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chemistry, Uncategorized

What kind of change is it?

A friend of mine had a disagreement with some colleagues at a pd session. My friend correctly asserted that when you put ice into a blender for a smoothie, the ice does not undergo a state change, except for some minor melting due to heat from friction. The ice will melt as the smoothie warms up but blending the ice, ie chopping the ice into tiny pieces does not constitute a state change.

While I worry that my friend was unable to convince her colleagues who may have therefore gone and taught this misunderstanding to their elementary students; I do also love conversations like this because they reveal questions that can be answered. I also find myself marveling at how logical some scientific misconceptions seem. It does seem that the ice is gone in the smoothie because it no longer demonstrates, in a visible way, the property of hardness.

So what is a state change?

A state change is a change to the physical state between solid, liquid, and gas. It is reversible and does not involve any chemical change. It does however involve absorbing or losing energy. The more energy the particles have, the more they move, and the more space they take up.

So, even though the ice appears to move more after it is blended into a smoothie, the water molecules have not absorbed additional energy at this point to trigger a state change. Therefore, even though we think of ice as solid and unmoving and water as being able to flow and the smoothie filows the water is still ice but appears to flow becaus it has been chopped into many small pieces suspended in a mixture.

It’s a logical misconception. It makes sense from observational evidence, but my friend was right: the ice in the smoothie has not changed state.

About Tai Munro

I am passionate about making science, sustainability, and sport accessible through engaging information and activities.

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