Science Expo 2013
Introduction
As all people know, we as humans need air in order to survive. We are affected by the absence of air, without it we would not be able to live. In our project we are testing to see whether other things in our world, take water as an example, are affected by the absence of air and matter.
Purpose
The purpose of this experiment is to determine if a vacuum affects the temperature which water changes states at.
Hypothesis
If water is put in a vacuum, then there will be no difference in the at which the water changes states.
Materials
1 vacuum chamber
1 large metal pot
2 cups of 70 degree tap water for inside the vacuum chamber
1 thermometer
1 glass bowl
1 weight (jam jar full of coins)
More room temperature water for the pot
Procedure
1. The 70 degree water was placed inside the vacuum chamber and the thermometer was placed in as well along with the weight at the bottom of the container
2. The vacuum chamber was pressurized to a 2/3 vacuum, the highest most machines can go
3. The water was boiled and the glass bowl was placed on the bottom of the pot in order to have the metal pot not touch the plastic vacuum chamber
4. The vacuum chamber was placed on the bowl in the boiling water
5. The temperature was recorded when the water in the vacuum chamber began to boil
6. Even though we could have repeated all the steps again with the container unpressurized, we did not have to because it is a known fact that, by sea level, water boils at exactly 100 degrees celsius
As all people know, we as humans need air in order to survive. We are affected by the absence of air, without it we would not be able to live. In our project we are testing to see whether other things in our world, take water as an example, are affected by the absence of air and matter.
Purpose
The purpose of this experiment is to determine if a vacuum affects the temperature which water changes states at.
Hypothesis
If water is put in a vacuum, then there will be no difference in the at which the water changes states.
Materials
1 vacuum chamber
1 large metal pot
2 cups of 70 degree tap water for inside the vacuum chamber
1 thermometer
1 glass bowl
1 weight (jam jar full of coins)
More room temperature water for the pot
Procedure
1. The 70 degree water was placed inside the vacuum chamber and the thermometer was placed in as well along with the weight at the bottom of the container
2. The vacuum chamber was pressurized to a 2/3 vacuum, the highest most machines can go
3. The water was boiled and the glass bowl was placed on the bottom of the pot in order to have the metal pot not touch the plastic vacuum chamber
4. The vacuum chamber was placed on the bowl in the boiling water
5. The temperature was recorded when the water in the vacuum chamber began to boil
6. Even though we could have repeated all the steps again with the container unpressurized, we did not have to because it is a known fact that, by sea level, water boils at exactly 100 degrees celsius
Results
The results show that the water in the vacuum boiled at 75˚C, 25˚ cooler than boiling point at sea-level.
The results show that the water in the vacuum boiled at 75˚C, 25˚ cooler than boiling point at sea-level.
Discussion
In our hypothesis we stated that there would be no difference at which water changes states at if it is put in a vacuum and pressurized. This hypothesis was proven incorrect because the water boiled at 25˚ cooler than the boiling point of water at sea level.
In this experiment the dependent variable was the pressure the water was under and the independent variable was the point at which the water boiled .
All the variables were considered when conducting this experiment, the vacuum chamber that we used was sealed to prevent any air from coming in. Also, as the definition of “boiling” we used the state at which many bubbles had formed. The term “sea-level” as a way of measuring atmospheric pressure is a loose term. We did take this into consideration, understanding that the atmospheric pressure at sea-level does change on a daily basis, but it would not be enough to change the outcome of this experiment.
For this experiment, the reason we tested state change from liquid and gas instead of solid to liquid is because ,when ice is melting, it is both a solid and a liquid at once. Therefore, that would mean that is would be hard to put a defining moment on when to record the temperature, whereas with liquid to boiling is a very visible and fast change.
Boiling occurs when a liquid’s molecules have enough energy to break free from the surrounding ones (Paul Walorsk, 2013). The only thing thats keeping water in its liquid state is atmospheric pressure, so if you remove all the pressure, there is nothing holding the molecules in place and they become a gas. This is exactly what a vacuum does, it takes away all the particles, lowering the atmospheric pressure. This would mean that the water would boil sooner. In a perfect vacuum, water would go straight from a solid to a gas. Now on earth, people have never been able to create a perfect vacuum, most likely because it doesn't even exist in space, there is always a few atoms of molecules left. The closest thing people have ever come to creating a perfect vacuum
is 0.00000000001 atmospheric pressure which is about a 99.9999999999% (Oxford University, 2008) vacuum (seriously), the only thing that people can't get out are the last traces of hydrogen.
The theory of vacuums originated as far back as ancient Greece, where great philosophers such as Aristotle and Lucretius fought about the idea of the existence of a void or vacuum. In 1654 a german scientist named Otto von Guericke invented the first vacuum pump (the object used to create a vacuum) and later in 1855 Heinrich Geissler went further and created the first pump capable of creating a partial vacuum.
Vacuums have come a long way since then and people know much more about the science behind them than they used to. Technology will advance and people will create things not even dreamt about in ancient Greek times. By creating a vacuum and making water boil 25˚ cooler that it should have under regular circumstances, we have done something that was not intended to happen on planet earth for there is no natural ones around.All of what we have done here today was only a theory 300 years ago and we hope that you see the importance of this as it shows how much air (or the absence of it) affects the world as we know it.
In our hypothesis we stated that there would be no difference at which water changes states at if it is put in a vacuum and pressurized. This hypothesis was proven incorrect because the water boiled at 25˚ cooler than the boiling point of water at sea level.
In this experiment the dependent variable was the pressure the water was under and the independent variable was the point at which the water boiled .
All the variables were considered when conducting this experiment, the vacuum chamber that we used was sealed to prevent any air from coming in. Also, as the definition of “boiling” we used the state at which many bubbles had formed. The term “sea-level” as a way of measuring atmospheric pressure is a loose term. We did take this into consideration, understanding that the atmospheric pressure at sea-level does change on a daily basis, but it would not be enough to change the outcome of this experiment.
For this experiment, the reason we tested state change from liquid and gas instead of solid to liquid is because ,when ice is melting, it is both a solid and a liquid at once. Therefore, that would mean that is would be hard to put a defining moment on when to record the temperature, whereas with liquid to boiling is a very visible and fast change.
Boiling occurs when a liquid’s molecules have enough energy to break free from the surrounding ones (Paul Walorsk, 2013). The only thing thats keeping water in its liquid state is atmospheric pressure, so if you remove all the pressure, there is nothing holding the molecules in place and they become a gas. This is exactly what a vacuum does, it takes away all the particles, lowering the atmospheric pressure. This would mean that the water would boil sooner. In a perfect vacuum, water would go straight from a solid to a gas. Now on earth, people have never been able to create a perfect vacuum, most likely because it doesn't even exist in space, there is always a few atoms of molecules left. The closest thing people have ever come to creating a perfect vacuum
is 0.00000000001 atmospheric pressure which is about a 99.9999999999% (Oxford University, 2008) vacuum (seriously), the only thing that people can't get out are the last traces of hydrogen.
The theory of vacuums originated as far back as ancient Greece, where great philosophers such as Aristotle and Lucretius fought about the idea of the existence of a void or vacuum. In 1654 a german scientist named Otto von Guericke invented the first vacuum pump (the object used to create a vacuum) and later in 1855 Heinrich Geissler went further and created the first pump capable of creating a partial vacuum.
Vacuums have come a long way since then and people know much more about the science behind them than they used to. Technology will advance and people will create things not even dreamt about in ancient Greek times. By creating a vacuum and making water boil 25˚ cooler that it should have under regular circumstances, we have done something that was not intended to happen on planet earth for there is no natural ones around.All of what we have done here today was only a theory 300 years ago and we hope that you see the importance of this as it shows how much air (or the absence of it) affects the world as we know it.
Conclusion
In our experiment, we have shown that water in a vacuum boils at a lower temperature than at atmospheric pressure at sea level (100˚C). Once we had subjected the water to a vacuum (although not a perfect one) the water boiled at seventy five degrees celsius. Therefore we can conclude that the boiling point of water is dependent upon the surrounding atmospheric pressure.
If we did another experiment like this in the future one addition would be to add impurities to the water. Salt for example is used to increase the boiling point of water in cooking. Then we could repeat the experiment with the water and salt solution in a vacuum. It would be interesting to note if the difference in boiling temperature between water and water with salt is the same under both test conditions (in a vacuum and not in a vacuum). Also if we redid this experiment it would be interesting to see what would happen if it a stronger vacuum was used (ex. ¼ atmospheric pressure) to see if that would change the results.
In our experiment, we have shown that water in a vacuum boils at a lower temperature than at atmospheric pressure at sea level (100˚C). Once we had subjected the water to a vacuum (although not a perfect one) the water boiled at seventy five degrees celsius. Therefore we can conclude that the boiling point of water is dependent upon the surrounding atmospheric pressure.
If we did another experiment like this in the future one addition would be to add impurities to the water. Salt for example is used to increase the boiling point of water in cooking. Then we could repeat the experiment with the water and salt solution in a vacuum. It would be interesting to note if the difference in boiling temperature between water and water with salt is the same under both test conditions (in a vacuum and not in a vacuum). Also if we redid this experiment it would be interesting to see what would happen if it a stronger vacuum was used (ex. ¼ atmospheric pressure) to see if that would change the results.