Science Buddies: "Ask an Expert"

I'm curious which would cause a greater burn and why: 50 ml vs 500 ml of water at 90degrees Celsius. My teacher hasn't really explained the concept and I'm preparing for an upcoming test.
Thanks,
Megan

The 500 ml would cause the greater burn since it has 10x the amount of liquid and would stay hot longer thus causing a greater burn.

Why would you get a burn from hot water? It is sitting in a pot and you are not in contact with it. You are in contact with air, which holds much less heat than water and is also at a lower temperature.

What causes the hot water to burn you? It is heat from the hot water transferring to your skin, heating the skin up, thus raising its temperature to the point where you get first pain then a partial cooking of the skin.

Suppose you took one tiny drop of hot water and dropped it on your skin. I don't know if that would be uncomfortable, but I'm pretty sure it would not result in a burn. It isn't just the temperature of the water, it is its heat content, and the more hot water, the more the heat content. That is the key to your question--if you want to cause a burn, you need to put enough heat into your skin to raise it's temperature until it hurts, then burns. The more hot water, the more heat.

Heat and temperature are different things, although they are related.