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This experiment requires the bottlecap with two bottlecaps and multiple tubes, two bottles (bottles designed for carbonated drinks are stronger than and therefore preferable to bottles designed for water, juice, tea, etc., bit either will do), a sink with hot and cold running water, a cup or shallow container, a ruler, and a teaspoon.
The tube common to both bottlecaps will be called the 'vertical tube', even if it isn't used in the vertical position.
The other two tubes coming from each bottlecap are the 'pressure tube' (the longer of the two) and the 'exhaust tube' (the shorter of the two), also sometimes referred to as the 'pressure-release tube'.
The word 'cap' will refer to the removable caps that can be used to seal the ends of the tubes.
Siphon a 'water plug' into each pressure tube and cap it, forming in each a sealed air column at least 20 cm long. This air column will be used to measure pressure changes. Measure the length of each air column.
Fill one bottle with water, and fill the other about 3/4 full. All the tubes except the vertical tube should be capped. The vertical tube should remain uncapped at both ends, and once the system is set up both ends should remain in water throughout.
Elevate one bottle and siphon water from that bottle into the other until both bottles are about equally full. The water level should be above the cylindrical portion of the bottle (within the rounded portion of the bottle near the top, above the cylindrical portion of the container). From the end of the siphoning process until completion of this exercise, both ends of the vertical tube should remain beneath the water level in their respective bottles, and the vertical tube should remain full of water.
Bring the bottles to the same vertical level and tighten both bottlecaps. Mark the 'water end' of the air column in each tube, or alternatively, carefully measure the lengths of the air columns in the two pressure tubes. Also mark or carefully measure the water level in both bottles.
Now raise one bottle about 30 cm higher than the other and take the measurements necessary to find the change in the water level in each bottle, and the change in the length of each air column.
Report your measurements and the change in each measurement below, along with an explanation of your results. Include a table indicating the percent change in the length of each air column, the percent change in water depth for each bottle, and your estimate of the change in air volume in each.
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The water levels are 16cm and 18cm. The air columns are 20cm . Nothing happened, it’s a sealed system.
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Uncap the exhaust tube in the upper container and repeat your measurements. Report your new information below, including tables indicating the respect percent changes in the various measured quantities.
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Saw a slight air column change in the lower bottle and maybe a cm change in the water column
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Lower the upper bottle to the level of the first. Take measurements to again determine the various changes. Report your new information below, including tables indicating the respect percent changes in the various measured quantities.
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Same as the first
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What do you think is going on here? Try to explain as much as you can about what you have observed:
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Nothing happens when the system is sealed. There has to be outside air to allow it to move. It also don’t do anything with the bottles side by side.
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Brief Bottle Experiment 3b
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Set up one bottle with water in it, the vertical tube extending down into the water. The pressure tube should be set up as before. The vertical tube should extend upward at least a meter. A convenient way to raise the tube is to put the second cap loosely on another bottle about half full of water, which can then be set on a shelf (just be careful to keep that end of the vertical tube out of water, and that cap loose so the upper end of the tube remains at atmospheric pressure).
Seal the cap in the lower bottle so you can squeeze water into the vertical tube. Give the tube a squeeze of about 2 on your 1-10 'squeeze scale', and do whatever is necessary to get the data required to find the change in the vertical level of the water in the vertical tube, and accompanying percent change in the length of the air column.
Repeat for squeezes of 5 and 8 on your 'squeeze scale'.
Report what you measured, how you measured it and what your measurements were.
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Squeeze of 2: 28cm of water raised, about a 30% change.Squeeze of 5: 90cm of water raised, about a 90% change
Squeeze of 8: The entire vertical tube filled up and went into the bottle. The vertical tube is approx. 110cm so 110%
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Give a table of the heights to which water was raised vs. the length of the air column as a percent of its original length. Add a third column which gives the pressure resulting from each squeeze, as indicated by the height of the water in the vertical tube (that pressure should be given in Pascals).
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Heights (cm): 28cm, 90cm, 110cm
Percent change in length of air column :28%, 90%, 110%
Pressure (pascals): squeeze 2, 5, 8
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Based on your table, how many Pascals of pressure change should correspond to a 1% change in the length of the air column?
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Brief Bottle Experiment 3c
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Repeat experiment 3 b, with one modification: Instead of squeezing the bottle to raise water, you will heat it up, using hot tap water.
Heat the system gradually, by first turning on the water so that is just trickles down one side of the container. Adjust the flow so that the water in the vertical tube rises just above the bottlecap. Take measurements to determine the vertical position in the tube, and the change in the length of the air column in the pressure tube compared to its original length.
Increase the flow of hot water so that the level in the vertical tube increases by another 10 cm or so, and repeat your measurements.
Repeat this process for two more steps.
Report your data in the usual manner, with at least a brief explanation, and include a table of the heights to which water was raised vs. the length of the air column as a percent of its original length. Add a third column which gives the pressure resulting from each squeeze, as indicated by the height of the water in the vertical tube (that pressure should be given in Pascals).
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When I trickled the hot tap water, hitting the side, I saw no change in water level.
When I increased the flow of hot water a stream, and measured 12cm, it took 50 seconds.
When I increased the flow of hot water to a good stream, and measured 10cm, it took 15 seconds.
When I increased the flow of hot water to wide open, and measured 10cm, it took 5 seconds.
With the increase in temperature and volume of water flowing on it, caused the system to increase at a more rapid rate.
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Now set the vertical tube to allow water to run out so that it could be collected at the vertical level of your last measurement, and turn the tap on full. You won't need to measure the collected water, but watch the pressure tube as the water flows out and report what you observe.
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Water flowed out of the pressure tube.
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Sketch a pressure vs. volume graph for the process you observed (that is, the pressure of the gas in the bottle vs. the volume of the gas in the bottle). You may use reasonable estimates for the volumes.
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Looked like a e^-x function
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Brief Bottle Experiment 3d
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The setup is the same as for experiment 3 c, except that this time the vertical tube won't all be vertical.
Let the vertical tube flop around any way it will, but have the end of the tube 40 cm above the water in the bottle.
Take data to determine the change in the length of the air column in the pressure tube, relative the the original atmospheric-pressure length, as you heat the system until water begins to flow slowly out of the tube. Allow water to flow slowly out as you make a measurement.
Report you data and how you measured it, then answer the question: What is the length of the air column, as a percent of its atmospheric-pressure length?
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I observed that this system moves a LOT faster than the last one.
Once you uncap the pressure tube on the lower bottle, the water starts pushing out the tube instead of filling of the other bottle.
Test 1: showed that when both pressure tubes were in the capped position, having hot water run over it, it pushed water out of the supply bottle into the other bottle and began siphoning the water.
Test 2: Once I got the bottle siphoning again and released the pressure off of the supply bottle, it quit siphoning and equalized.
Test 3: When it started siphoning, I left the supply bottle pressure tube capped, and opened the pressure tube on the other bottle, it stopped the siphoning completely and equalized.
Test 4: The bottle wouldn’t siphon AT ALL when both pressure tubes were in the un-capped position.
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Repeat, but this time have the middle of the tube at least 60 cm above the water level in the bottle. The end will still be at the 40 cm height. Adjust the flow of the tap so that no air enters the tube from either end during your measurement of the pressure tube.
Report you data and how you measured it, then answer the question: What is the length of the air column, as a percent of its atmospheric-pressure length?
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The higher you move it, the longer it’s going to take to do it.
Also, the higher you go, the catched bottle water will soon go back into the supply bottle again.
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