OS3 Volume of Water

Volume is a measure of how much stuff is in so much space. This is a special kind of space.

A line goes between two points or places. You can’t put much stuff into a line.

When you have several lines joined together, you have a shape. You can put stuff into the space between the lines but only one layer deep.

If you have a lot of the same shapes piled up on top of each other, you can put lots of stuff inside the space inside. Volume has three parts: length, width and depth.

In chemistry the basic volume has a length of 1 cm, a width of 1 cm and a depth of 1 cm. The amount of space is 1cm x 1 cm x 1 cm or 1 cm3 or 1cc [cubic centimeter].

For gases this basic measure is increased to 1 cubic meter. We can see why by comparing how water volume and air volume behave.

Question: How do water volume and air volume compare?

Materials:

1 or 2 syringes holding 12 cc to 20 cc

Note: You can probably get these from a veterinarian. You do not need needles.

Tape

10 cm length of aquarium or other soft plastic tubing that fits tightly on the syringe

Paper

Custard cup of water

Procedure:

Note: If you have only one syringe, do everything with the air, then do everything with the water.

Pull the plunger back on one syringe to the highest mark to fill it with air

Record how much air is in the syringe

Put a piece of tape over the open end and fold it around the end to seal the syringe.

Hold a finger over the tape on the end and push down on the plunger until it stops

Record the reading of air in the syringe

Put the end of the other syringe in the water and pull back on the plunger a little ways

There will be air in the syringe so turn the end straight up and push down on the plunger until the air is out

Now fill the syringe to the same mark as the air

Water is drawn up into a syringe which is sealed up. Can you push on the plunger and make the water take up less volume?

Record the amount of water in the syringe

Dry the end of the syringe and tape it closed

Hold a finger over the taped end and push down on the plunger until you can’t push it down any more

Record the amount

Push the end of the tubing onto the end of the syringe

Tape the tubing tightly onto the syringe so it will not leak

Pull the plunger back filling the syringe with air to the same mark as before

Record the amount

Make a paper plug to push into the open end of the tubing

The paper plug seems to fill the end of the tubing. It is tight, as tight as I could make it. Will it stop the air from escaping?

Note: I make this paper plug by taking a small piece of paper about 20 cm square. I push down on the center and twist the outer part around tightly to make a cone. The end of the cone is pushed into the tubing then twisted in until I can’t get any more of the plug into the tubing.

Slowly push the plunger down observing how the volume changes and the plug acts

Pull the plug out of the tubing

Put the end of the tubing into the cup of water and half fill the syringe

Hold the end of the tubing straight up and pull all the water into the syringe

Push down on the plunger enough to push all the air out

Put the tubing back in the cup of water and fill the syringe to the same mark as before

Record the amount

Make a new paper plug and push it into the end of the tubing

Note: For this last part it is a good idea to go outside or inside a shower stall.

Slowly push down on the plunger observing how the volume changes and the plug acts

Observations:

Volume of air

Starting:

Ending:

How it feels pushing the plunger down:

Volume of water

Starting:

Ending:

How it feels pushing the plunger down:

Amount of air in tubing

Starting:

Ending:

How the volume and plug act:

Amount of water in tubing

Starting:

Ending:

How the volume and plug act:

Conclusions:

Did the amount of air in the syringe change or only the volume? Why do you think so?

Did the amount of water in the syringe change? Did the water volume change? Why do you think so?

Does air have a definite, unchanging volume? Why do you think so?

Does water have a definite, unchanging volume? Why do you think so?

How does this explain the changes in height you saw in the last Project?

Tractors and other big machines have fluid filled tubes to lift buckets and other parts. Pressure is put on the fluid at one end of the tube to move things on the other end. Why do they use fluid and not air? [This is called hydraulics.]

What I Found Out:

I had one 12 cc syringe so I did everything with air first. The first step was to pull air into the syringe and tape the end.

My syringe held 10 cc of air. When I held the tape on the end and pushed the plunger, it moved quickly to start with. Then it got harder and harder to push down until it stopped. The syringe now read 3 cc.

The amount of air in the syringe stayed the same but the volume didn’t because I could push the plunger down. Air has no definite volume and can be compressed or stretched out.

Next I taped the tubing on the syringe. I held the end firmly closed and pushed down on the plunger. this time it went down to 5 cc but crept back up to 6 cc when I quit pushing down.

I made a paper plug and pushed it into the end of the tubing. I thought this was very tight but, when I pushed down on the plunger, it went down all the way as the air leaked out around the paper plug.

After taking the tubing off the syringe, I filled it with 10 cc of water and taped the end. This time, when I pushed the plunger, the plunger would not move at all. The 10 cc of water stayed 10 cc so water has a definite volume.

Since the water takes up the same volume in any container, it will have a greater depth in a narrow space and a lower height in a wide space. This is what happened in the last Project.

Next I put the tubing back on the syringe. I put water in the syringe until it read 10 cc. Holding the end of the tubing, I pushed on the plunger and it did not move as I expected.

I made another paper plug and pushed it into the end of the tubing as tightly as I could. When I pushed on the plunger a few drops of water oozed out. Then the plug shot out of the tubing and across the lab table.

Machinery uses fluid because it doesn’t change volume. When pressure is put on one end, the pressure pushes on the other end to lift a bucket or other part.

I read in “Xplor” magazine from the Missouri Department of Conservation that bugs like spiders use hydraulics to move their legs. It gives them lots of power so jumping spiders can jump long distances very quickly to catch their next meal.

If you don’t get “Xplor” – it’s free to Missouri residents – check it out on the Conservation Department website http://www.mdc.mo.gov and sign up for it and “The Conservationist.”