From our chips model we agreed on the following:
1. The water level goes down over time in a cup in an open system. This means that the lid plays a role in keeping water there.
2. If the water level goes down, then the water has only one place to go, and that's in the air.
3. Since we can't see the water in the air, then it's got to have a lot of empty space around it like air molecules do.
1. The water level goes down over time in a cup in an open system. This means that the lid plays a role in keeping water there.
2. If the water level goes down, then the water has only one place to go, and that's in the air.
3. Since we can't see the water in the air, then it's got to have a lot of empty space around it like air molecules do.
All this "water in the air" talk got us thinking about how this may relate to water that appears on cups in closed systems. So we tested our thinking out with different cups, sealed them with lids and tape, and put really cold water inside.
And the findings of all our investigations were:
1. Water does appear on both the outsides of plastic and metal cups that have a lid and are sealed with tape.
2. The mass of these systems increases slightly, suggesting that new water was added to the system. We agreed that it had to come from the air (we even measured that there was water in the air with a hygrometer, which is a tool Mrs. Brinza found in a science cabinet that measures humidity, or water in the air).
3. We still had some doubt that there might be really small holes in the cup which could possibly account for water leaking through the walls, so we turned the water blue inside and re-ran the experiments. Wiping the water down from the outsides with a white tissue showed the water on the outside was clear, not blue like the insides.
4. We really thought about the weight, too, and recognized that if the cup was leaking, we wouldn't see an increase in mass, but rather no change. Since we saw a weight increase, it couldn't have been transferring from inside the cup to the outside.
We're wishing we could have more info on other things in our systems, like the lids and the walls (or materials of the cups). Maybe those things are playing a role in what we've been seeing happening with both the mass and the temperature changing (or not changing)!
1. Water does appear on both the outsides of plastic and metal cups that have a lid and are sealed with tape.
2. The mass of these systems increases slightly, suggesting that new water was added to the system. We agreed that it had to come from the air (we even measured that there was water in the air with a hygrometer, which is a tool Mrs. Brinza found in a science cabinet that measures humidity, or water in the air).
3. We still had some doubt that there might be really small holes in the cup which could possibly account for water leaking through the walls, so we turned the water blue inside and re-ran the experiments. Wiping the water down from the outsides with a white tissue showed the water on the outside was clear, not blue like the insides.
4. We really thought about the weight, too, and recognized that if the cup was leaking, we wouldn't see an increase in mass, but rather no change. Since we saw a weight increase, it couldn't have been transferring from inside the cup to the outside.
We're wishing we could have more info on other things in our systems, like the lids and the walls (or materials of the cups). Maybe those things are playing a role in what we've been seeing happening with both the mass and the temperature changing (or not changing)!