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jar
shallow
lighter
Put the candle in the candleholder.
Put the candleholder on the dish.
Fill the dish half full with water.
Light the candle.
Let the candle burn for two or three minutes
Carefully put the jar over the candle until the top of the jar rests on the dish
The candle stops burning.
The water in the jar rises.
Think about ：
What will happen?
Pair work : Do the experiment
⒈Put the candle in the candle holder.
⒉Put the candle holder on the dish .
⒊Fill the dish half full with water.
⒋Light the candle .
5.Let the candle burn for two or three minutes.
⒍Carefully put the jar over the candle
until the top of the jar rests on the dish.
⒎Examine the water in the jar. What can you see ?
Let’s answer !
Why did the candle stop burning?
How far does the water rise? Why?
Because the candle has used up all the oxygen in the air.
It rises about one-fifth of the jar. Because about one fifth of the air is made up of oxygen
Why did the water rise?
Because the force outside the jar is stronger than the force inside the jar.
There is about 20% oxygen in the air.