ok - for the Chemistry or physical science brainiacs....?

Question

my daughter is doing a science project, it involves a shallow saucer of water with a candle in the middle of it , then you put a mason jar over top of candle...fire goes out due to lack of oxygen,right....then the water in the saucer is vacuumed up into the jar.....please tell me what this process is called...and if you have any ideas what to title this project...i need good advice - thank you...

Answer 1

The candle needs oxygen to burn. When you cover the burning candle with the jar, the flame eventually goes out as soon as all of the oxygen is used up. Since there is no more oxygen under the cup, the rest of the gases (nitrogen, argon, carbon dioxide, and others) are exerting less pressure compared to the atmospheric air.

The greater atmospheric pressure on the outside of the bottle pushes the water in the pan up into the bottle.

However, there is another important factor that accounts for the rise in water level. The candle flame heats the air in the bottle, and this hot air expands.

When the flame goes out, the air in the jar cools down and the cooler air contracts. The contraction of the air draws the water up into the bottle.

Call this Effects of Atmospheric Pressure and Heat on Surface Displacement.

Answer 2

The candle heats up the air in the jar. As a result the air in the jar expands. As the air expands it has no place to go except out of the jar which it does and probally causes bubbles to form around the jar when the candle is lit. After the candle goes out, the air in the jar cools. As the air cools it begins to contract. This causes the pressure inside the jar to be less than the atmospheric pressure outside the jar. The vacuum inside the jar causes water to be sucked into the jar. The fact that oxygen is consumed or not has nothing to do with the experiment. IThe experiment appears to demonstrate the expansion and contraction of gasses with heat and cold and demonstrates fluid flow (air and water are both fluids) from areas of high pressure to areas of low pressure.

Answer 3

I misread the question. The suction is due to a difference in the air pressure from the inside of the jar and the surrounding air. When the flame goes out inside of the jar the air cools. Since air pressure and tempurature are directly related, the pressure also goes down. Now the pressure in the jar is less than that of the surrounding air. This creates suction.

Answer 4

I don't know if it's called something specific but the reason is actually pressure, the gas inside should become hotter, which makes it expand. once the oxygen is used up, the candle goes out, that's correct, but this causes the gas inside to cool, so it gets smaller, and therefore pressure decreases. Since the pressure inside is less than outside, the water is "pushed" up inside the jar.

Answer 5

I would say the process is evaporation, because the short instance of heat would turn the liquid into a vapor. I don't necessarily know what you mean by vacuumed though.

You could title it the Effects of Oxygen or something like that, if you want a general title.

Answer 6

try this page http://www.planet-science.com/wired/shake_down/15_fire.html hope it helps