Why Does My Tea Container Explode When I Shake It?

  • Context: High School 
  • Thread starter Thread starter ErectusX
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Discussion Overview

The discussion revolves around the phenomenon of a tea container experiencing pressure buildup and occasionally popping its lid when shaken after being filled with hot water, tea bags, and sugar. Participants explore the underlying physics of pressure, steam, and heat transfer in this context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that shaking the container causes the air inside to heat rapidly, leading to expansion and increased pressure, which results in the lid popping open.
  • Another participant points out that the pressure buildup is primarily due to steam rather than just air, emphasizing the role of the phase boundary between water and gas in accelerating the steaming process.
  • A participant reflects on the time it takes for heat to transfer to the air above the water, indicating a misunderstanding of the heating dynamics involved.
  • Some participants engage in light-hearted banter, contributing humor to the discussion without addressing the technical aspects.

Areas of Agreement / Disagreement

There is no clear consensus on the primary cause of the pressure buildup, with some participants attributing it mainly to steam and others to the rapid heating of air. The discussion remains unresolved regarding the exact mechanisms at play.

Contextual Notes

Participants reference the ideal gas law and the importance of using the Kelvin scale for temperature comparisons, but there are unresolved assumptions about the dynamics of heat transfer and pressure changes in the container.

ErectusX
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Hello, I'm new here.
I hope I do not offend all of you physics gurus with my simple question. Here is the scenario:

I have a Rubbermaid 2.5 liter container that I like to fill up with hot (boiling) water, 3 teabags and few spoons of sugar. I'm not sure what kind of plastic exactly it is, but it does not melt or shrink like a regular PET bottle. It is pretty sturdy. When I close the lid and shake the hot tea inside to make it mix with the sugar, pressure builds up inside and (occasionally) pops open the lid. I usually release the steam inside before it does this.

Can anyone explain why this is happening? What happens to the steam as it get agitated?

Thank You! :smile:
 
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The water's hot, near boiling. You put it in a bottle with a little cool air, close it, and then rapidly heat the air to nearly 100 degrees C by shaking the bottle. The air expands, and increases the pressure inside the bottle until the lid pops open.

- Warren
 
I see. Thanks. For some reason I thought the air above the water would get heated too (at the instance of me pouring the hot liquid in the container). I did not realize it takes time to transfer heat to a layer of air.

So when I mix it, the exchange surface area between the tea and air increases dramatically and helps to speed up the heating --> expansion of the cooler air.

I wish I was a little brighter ;-) Thanks chroot!
 
I think the lid pops up because of high pressure alright. But the high pressure is mainly due to the steam, not only the air. In the formula PV/T =constant, T here changes not very much because you have to use the Kelvin scale. You have to add with 273 K so you compare T1=273+25 and T2 =273+90, the ratio T2/T1 is not very high surely (appr. 1.2)
The reason here is that when you shake the container, you increase the phase boundary between water and gas so it accellerates the steaming process. The water vapor of course will build up pressure and pop up the lid consequently.
You can test this very easily. After the lid has been popped off, you put it on and shake the container again. Probably the lid will pop out once more if the water is still hot enough.
 
Last edited:
ErectusX said:
Why does my tea blow up? :-)
Because, when you mix up the tea that way, you make tea 'n' tea!

<sorry, couldn't resist>
 
Gokul43201 said:
Because, when you mix up the tea that way, you make tea 'n' tea!
I'm ashamed to say that took me a couple of seconds, but now I'm quietly giggling to myself...:smile:
 
Funny! :P
 
Gokul43201 said:
Because, when you mix up the tea that way, you make tea 'n' tea!

<sorry, couldn't resist>

Good to see some wit in these here forums. :smile:
 

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