science for not-so-tinies: dry ice
Mar. 18th, 2020 02:51 pmChaos sent the kids some dry ice (it was neat, the company threw in some ice cream for Josh's birthday) so we did some science!
Project: What Even Is Dry Ice
Materials: dry ice, tongs
Explanatory details: ok, so it's ice, but it's not water ice, and it's super cold
How did it go: Fine.
Things we talked about: states of matter, transitions between states of matter
Project: Fog
Materials: dry ice, tongs, bowl of water
Explanatory details: dropped a chunk of dry ice into water, creating delightful fog
How did it go: Great!
Things we talked about: more states of matter; sublimation is different than melting
Project: Wait, *What* Is This Stuff Again?
Materials: dry ice, tongs, bowl of water, match
Explanatory details: lowered lit match into fog and watched it go out
How did it go: Good although matches make some of us nervous.
Things we talked about: The part of the air we breathe is the same part that a fire needs to burn; the match goes out in the CO2 just like a candle under a glass goes out when it uses up the oxygen (a previous experiment that I was excited that Junie remembered). Also, the CO2 is heavier than the air, which is why it stays down in the bowl/spills out as fog rather than just shooting up to the ceiling like helium would.
We did three more experiments with the dry ice.
This experiment was proposed by Quentin, who wrote it up for us:
Question: If you put green food coloring in water and then put dry ice in the water, will the fog be green too?
Hypothesis: The fog will be green.
Result: The fog was still grey.
Things we talked about:the color stayed in the water, it didn't go into the CO2 gas.
This one was mine:
Question: Does the CO2 bubbling through the water affect the pH of the water?
Hypothesis: Some CO2 will dissolve into the water, lowering the pH of the water.
Result: pH paper dipped in the water before adding the dry ice turned a pale greenish-yellow, indicating a pH of about 7. pH paper dipped in the water after the dry ice was in there for awhile turned orangeish-yellow, indicating a pH around 6 or slightly below (but higher than 5), consistent with the hypothesis.
Things we talked about: More CO2 in the air means that a similar process of acidification is happening to the oceans. :(
We had all been interested to notice that previous experiments left behind "ice castings" of the chunks of dry ice, where the water in the bowl had frozen around the chunk which had then sublimated away, leaving a hollow in the ice in the shape of the dry ice chunk. Junie and I were curious what would happen if we completely submerged a chunk of dry ice in water - could we completely encapsulate the dry ice in water ice? Here's Junie's writeup:
Question: If a piece of dry ice is dropped into a 1 foot bucket of water, will the water freeze around it in a shell of ice, or will the gas from the dry ice stop it from forming a shell?
Hypothesis: I think that the water WILL form a shell around the dry ice after a while because then all the gases and bubbles will be gone.
Result: At first, there were a LOT of bubbles and fog! After 10-15 minutes the fog had stopped and there were less bubbles. After a few hours, the dry ice was gone, no more bubbles, and the water was still a liquid.
I will note that we abandoned the bucket and didn't check it frequently, so it's possible that there was a stage with a good shell that then melted again before we saw it... we tried it twice, but both times we got sidetracked. If our last piece of dry ice survives another night I might try it one more time tomorrow and try to check more frequently. Also in the interests of accuracy I think the bucket was more like 8 inches of water than a foot.
Project: What Even Is Dry Ice
Materials: dry ice, tongs
Explanatory details: ok, so it's ice, but it's not water ice, and it's super cold
How did it go: Fine.
Things we talked about: states of matter, transitions between states of matter
Project: Fog
Materials: dry ice, tongs, bowl of water
Explanatory details: dropped a chunk of dry ice into water, creating delightful fog
How did it go: Great!
Things we talked about: more states of matter; sublimation is different than melting
Project: Wait, *What* Is This Stuff Again?
Materials: dry ice, tongs, bowl of water, match
Explanatory details: lowered lit match into fog and watched it go out
How did it go: Good although matches make some of us nervous.
Things we talked about: The part of the air we breathe is the same part that a fire needs to burn; the match goes out in the CO2 just like a candle under a glass goes out when it uses up the oxygen (a previous experiment that I was excited that Junie remembered). Also, the CO2 is heavier than the air, which is why it stays down in the bowl/spills out as fog rather than just shooting up to the ceiling like helium would.
We did three more experiments with the dry ice.
This experiment was proposed by Quentin, who wrote it up for us:
Question: If you put green food coloring in water and then put dry ice in the water, will the fog be green too?
Hypothesis: The fog will be green.
Result: The fog was still grey.
Things we talked about:the color stayed in the water, it didn't go into the CO2 gas.
This one was mine:
Question: Does the CO2 bubbling through the water affect the pH of the water?
Hypothesis: Some CO2 will dissolve into the water, lowering the pH of the water.
Result: pH paper dipped in the water before adding the dry ice turned a pale greenish-yellow, indicating a pH of about 7. pH paper dipped in the water after the dry ice was in there for awhile turned orangeish-yellow, indicating a pH around 6 or slightly below (but higher than 5), consistent with the hypothesis.
Things we talked about: More CO2 in the air means that a similar process of acidification is happening to the oceans. :(
We had all been interested to notice that previous experiments left behind "ice castings" of the chunks of dry ice, where the water in the bowl had frozen around the chunk which had then sublimated away, leaving a hollow in the ice in the shape of the dry ice chunk. Junie and I were curious what would happen if we completely submerged a chunk of dry ice in water - could we completely encapsulate the dry ice in water ice? Here's Junie's writeup:
Question: If a piece of dry ice is dropped into a 1 foot bucket of water, will the water freeze around it in a shell of ice, or will the gas from the dry ice stop it from forming a shell?
Hypothesis: I think that the water WILL form a shell around the dry ice after a while because then all the gases and bubbles will be gone.
Result: At first, there were a LOT of bubbles and fog! After 10-15 minutes the fog had stopped and there were less bubbles. After a few hours, the dry ice was gone, no more bubbles, and the water was still a liquid.
I will note that we abandoned the bucket and didn't check it frequently, so it's possible that there was a stage with a good shell that then melted again before we saw it... we tried it twice, but both times we got sidetracked. If our last piece of dry ice survives another night I might try it one more time tomorrow and try to check more frequently. Also in the interests of accuracy I think the bucket was more like 8 inches of water than a foot.