Hot Stuff! Calibrate your oven.

By Simon Shapiro

One of the many things that can go wrong for novice bakers is that your oven can be inaccurate. Impress your family and friends by calibrating your oven using phase transitions.

While you can't depend on your oven manufacturer, you can depend on the fact that sugar melts at 366°F (186°C). And since we're impressing friends and family, tell them that sugar transitions from the solid (crystalline) phase to the liquid phase at 366°F.

Here's how you do it:

• Set your oven temperature to 365°.

• Put half a tablespoon of sugar in an ovenproof dish.

• When the oven reaches its target temperature, put the dish in the oven and leave it there for 15 minutes.

• Check to see whether the sugar has melted. Use oven gloves to handle the dish. It may look the same, but it will be really hot! Don't burn yourself!

Sugar is still crystalline

... or ...

Sugar is melting

If the sugar is still crystalline, increase the oven temperature by 5°, and leave the sugar in for another 15 minutes. If it's melted, let the oven cool a little, set it to 5° lower, and put a fresh half tablespoon of sugar in for fifteen minutes. Repeat the process until you discover a temperature setting where sugar doesn't melt and a setting where it does melt.

Some ovens won't let you set a temperature that's not a multiple of 5. If your oven allows more precise settings, you can keep going to find the exact setting at which the sugar melts.

When I did this, I found that the sugar melted at a setting of 357°. So now I know to set my oven to 9° lower than the temperature I really want.

A Science Trick to Try at Home

Instructions from Margriet Ruurs

You -- yes, you, right there -- can turn two solids into one liquid. It's not magic. It's science.

How can you turn a solid substance into a liquid without adding any liquid? Here’s a fun trick to try at home. All you need is a spoonful of sugar and some fresh yeast. You can buy fresh yeast at any bakery.

Instructions:

Fresh yeast. Image by Hellahulla, from
Wikimedia Commons

• In a small bowl put a small slice of the fresh yeast.

• Sprinkle a spoonful of sugar on top.

• Just let it sit for a few minutes. You’ll notice the yeast turning darker.

• After a while, take a teaspoon and stir the two solid materials. 

You’ll find that both solid ingredients have turned into a liquid all by themselves! This process is called osmosis.

White sugar is made up of solid crystals -- until the crystals
meet the moisture in the fresh yeast.

The sugar crystals dissolve because of the humidity (dampness) in the fresh yeast, forming a highly concentrated sugar solution. But the sugar concentration inside the yeast cells is low.

The liquid containing a large amount of sugar has a natural tendency to mix with the liquid that has less sugar and even out the sugar concentration. The yeast cell membranes separating the two solutions aren't strong enough to overcome that force, so the membranes break down. Then the water inside the cells bursts out. Pretty soon, all the sugar is completely dissolved in the released water.

And presto! -- Osmosis has turned your two solids into one liquid. It's a little magical, but it's science magic!