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To all of you hot beverage drinkers...

goalkeeper0

Entry posted by goalkeeper0

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As APs are nearing closer, caffeine seems like the secret to success. Staying up late takes a toll on the body, and drains you of energy. Therefore, in the morning, it is very common to see kids and adults carrying around a cup of coffee or tea for the caffeine boost. Nobody wants to fall asleep in class. For those who do consume these beverages here is a disclaimer:

Beware of water heated in a clean container in the microwave. Unlike when water heats up on the stove, water heated in a microwave can reach a temperature above its boiling point, and remain in liquid phase. This is called "superheating." Normally, when the temperature of the water exceeds its boiling point, the water slowly becomes a gas. But, in the microwave, boiling is hindered by lack of nucleation sites to form bubbles. A nucleation site can be a scratch in the container, a spec of dust, or any place where there is high surface area relative to volume. Also, the surface tension of the water in the mug suppresses the growth of bubbles. When the timer buzzes, and the mug is removed from the microwave, the water in the cup may appear placid, without bubbles (So, you think that the water's temp. is below 100 degrees Celsius). You are wrong, the water may be well above its boiling point. As soon as a powder such as a sugar or teabag is added to the water, the sudden addition of many nucleation sites can trigger an explosion of froth. Instantaneous boiling is induced. This can cause nasty burns to your skin.

The "superheating" of water is easily preventable. First off, do not set the timer on the microwave for very long (over five minutes). Also, you may leave a nonmetallic object in the glass while it heats such a wooden stick to add nucleation sites. Lastly, stay away from heating and then reheating the same water multiple times in the microwave. Don't let this post scare you into never using a microwave again. Superheating isn't too common unless you set the microwave timer for 20 minutes instead of two, and then come back and find a very hot cup of water. Moral of the story: be safe when using the microwave.

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