Can the ocean freeze?
Last year we had been to Leh, Ladakh. There the tour guide was explaining to us how the Zanskar river freezes during winter where visitors go for trekking on the frozen river.
It was amusing to my son who asked me, if Pacific ocean would also freeze just like the rivers in Leh. I replied to him to think about it and promised that we would do an experiment to verify when we get back home. So, to explain to him I decided to the following experiment in the class.
Ocean Freeze
The experiment was about salt water freezing. We had a discussion about why the ocean does not freeze at 0 degrees. Kids came up with different reasons. Guess what they were!
There are 4 main factors for that.
1. High concentration of salt in the ocean water lowers the freezing point from 0 degrees to -2 degree centigrade.
2. The constant motion of the ocean currents keeps the water molecules from freezing into ice crystals.
3. The larger the volume of water, the more heat has to be removed in order to freeze it. A teaspoon of water placed in the freezer will become completely solid long before a gallon jug of water.
4. Earth's internal heating ....As miners dig into the earth they feel very hot though it is farther away from the sunlight. The reason for this is that the earth has its own internal heat source which is driven primarily by the nuclear decay of elements inside earth's mantle.
To test out if the salt in the water does affect the freezing point of water we did a small experiment.
We took a popsicle mould and poured into each slot different liquids.
Procedure
1. We mixed 2 tsps of salt in 50 ml of water for 1 popsicle mould.
2. Mixed 4 tsps of salt in another 50 ml water for another mould.
3. Plain 50 ml water for the third mould.
We kept it in the freezer all at once. After about 4 hrs later we checked to find out that the plain water had frozen, 2tsp salt dissolved water had partly frozen whereas the 4tsp salt dissolved water was watery still.
So, our hypothesis about salt water proved to be right.
It was amusing to my son who asked me, if Pacific ocean would also freeze just like the rivers in Leh. I replied to him to think about it and promised that we would do an experiment to verify when we get back home. So, to explain to him I decided to the following experiment in the class.
Ocean Freeze
The experiment was about salt water freezing. We had a discussion about why the ocean does not freeze at 0 degrees. Kids came up with different reasons. Guess what they were!
There are 4 main factors for that.
1. High concentration of salt in the ocean water lowers the freezing point from 0 degrees to -2 degree centigrade.
2. The constant motion of the ocean currents keeps the water molecules from freezing into ice crystals.
3. The larger the volume of water, the more heat has to be removed in order to freeze it. A teaspoon of water placed in the freezer will become completely solid long before a gallon jug of water.
4. Earth's internal heating ....As miners dig into the earth they feel very hot though it is farther away from the sunlight. The reason for this is that the earth has its own internal heat source which is driven primarily by the nuclear decay of elements inside earth's mantle.
To test out if the salt in the water does affect the freezing point of water we did a small experiment.
We took a popsicle mould and poured into each slot different liquids.
Procedure
1. We mixed 2 tsps of salt in 50 ml of water for 1 popsicle mould.
2. Mixed 4 tsps of salt in another 50 ml water for another mould.
3. Plain 50 ml water for the third mould.
 |
| Salt dissolved in water |
 |
| 2 different concentration of salt solution and one plain water popsicle |
We kept it in the freezer all at once. After about 4 hrs later we checked to find out that the plain water had frozen, 2tsp salt dissolved water had partly frozen whereas the 4tsp salt dissolved water was watery still.
So, our hypothesis about salt water proved to be right.
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