Book 1, Question 130
Boiling or Simmering? What's the Difference?
Boiling and simmering are two different ways to heat water. Heat makes water molecules move faster. Simmer is gentle heat with small bubbles that are steady and calm, while a boil is high heat with big, rolling bubbles at 100 degrees C. The page says a rolling boil is not always better for soup. Watch a pot with a grown-up as the bubbles change.
More fun facts
- Water boils when its vapor pushes as hard as the air pressing down on it. Then bubbles of vapor can escape.
- At normal sea-level air pressure, pure water boils at 100 degrees Celsius (212 degrees Fahrenheit).
- Once water in an open pot is boiling, it won't get any hotter, even if you turn up the heat.
- High up in the mountains, air pressure is lower, so water boils at a lower temperature.
- That is why some cake mixes have special high-altitude directions on the box.
- At the South Pole, the air pressure is about 20 percent lower than expected for its height, so water boils at an even lower temperature there.
Questions kids ask
Does turning up the heat make boiling water hotter?
No. Water in an open pot doesn't get hotter than its boiling point.
Why does water boil at a lower temperature in the mountains?
There is less air pressure up high, so the vapor can escape more easily.