Science Buddies: "Ask an Expert"

Hi,
I have already posted a topic, but i have'nt used it for a while so i think it was forgotten (hopefully it is ok that i'm starting a new one!)
For the trash to gas experiment, i was wondering why you have to use distilled water, why not regular water? i would like to know the answer in case it comes up while i'm presenting to my class or to a judge. So, why distilled water?

anna

Hi Anna:

I understand you are doing this Science Fair project idea:

https://www.sciencebuddies.org/science- ... p027.shtml

First, congratulations, you are obviously thinking critically about your experiment. That is a very positive recommendation of your project.

I think the use of distilled water is recommended in order to help control the variables in your project. You obviously could use any type of water and probably get the experimtnt to work, though perhaps the reproducibility wold be reduced. Ordinary water would contain unknown amounts of salts, organic compounds, and unknown living organisms which could interact with your other ingredients of the bottle in various unknowable ways. Distilled water should contain almost no dissolved salts and nonvolatile compounds, and should have far fewer types of living organisms than ordinary water.

I hope this helps. This sounds like a really fun project. I wish you every success with it!

Best regards,

Barrett L. Romlinson

Thank you very much, I really do appreciate it!

Thanks and regards,
Anna

hi,
(refering to trash to gas project)
i have another question. how do i establish whether the balloon is filled with air of gas? also with the experiment, how long will it take for the balloons to blow up, even a little?

anna

I am so sorry to be doing this. But I really really need help. I cannot figure out how to post a new topic in the sci fair forum. Please help.

Anna,

The bacteria present in the manure will make methane (and possibly some small amount of CO2 for their own respiration). You will be able to tell if you smell it because methane smells bad to most people (it's the gas that smells bad when someone passes gas). It will also burn if lit (have adult supervision and proper safety equipment if you decide to do this!).

Unfortunately, I don't know how long it will take to get a result. My guess is that you will at least see something within the first week, but that it may take several weeks before the balloons blow up enough to measure differences.

Burtonboi,

You hit the 'new topic' button at the top of the forum on the left, which I think you have already figured out how to do. I moved your topic to a more appropriate forum so you should be able to get help.