Inflating objects by evaporating urine

[AntonyJ]

Hi there,

Im conducting an experiment in which i am boiling a pot of urine that is covered with a plastic sheet.

As the water evaporates from the urine the steam causes the plastic sheet to inflate creating a domed shape.

The steam then condenses on the domed plastic sheet and drips down to the edges of the pot, collecting in a separate recepticle.

I am wondering for a given amount of water/urine, say 100ml, how much does the amount of air within the pot increase as it evaporates.

Thanks for any help.

Antony.

 

[mrspeedybob]

What do you mean by "air"?

 

[Drakkith]

During the boiling process you constantly have evaporation and condensation, so there is no simple answer. The faster you boil it the more steam will exist at one time inside the container.

 

[AntonyJ]

Hi, thanks for the reply, I've attached a picture which hopefully makes the experiment i was talking about a bit clearer.

The urine only fills a few millimeters of the pot. A container is then placed in the centre of the pot and the pot is covered with cling film. The pot is heated, water evaporates and condenses on the cling film and drips down into the central container.

The more the pot is heated, the more the cling film inflates due to the increased temperature of the air trapped inside of the pot at the start, and the steam that results from the heating. I was wondering if this rate of expansion is measurable.