Science Buddies: "Ask an Expert"

I want to do a science experiment which shows whether bottled water is safe in different situations. (some people say that bottled water, when left in the bottle, it causes cancer)
I'm thinking of freezing water, then waiting until its all the way melted, and when its room temperature. And, leaving the bottled water in the car. For a control, a regular bottle of water, left at room temperature.
Is this enough variables?
Personally, I think there aren't enough, but I can't figure out what else I can.
Also, what water quality tests should I do to see whether the water is safe?
Thanks.

Are you trying to determine if the water contains carcinogens? If so you will need to determine what substance you want to measure and how to measure it. Does it diffuse into the water under different circumstances (freezing, heating etc)? Some research on plastics may be in order.

Thanks, you have understood my question perfectly.

Hi Blueswim,
The sorts of chemicals that leach out of plastics (try an internet search for "phthalates" or "Bisphenol A") are usually present in the water at very low concentrations. To measure the low concentrations of those sorts of chemicals requires some very expensive laboratory equipment and complicated procedures. You would probably need to find a mentor at a university or research laboratory to do this sort of experiment. If that sounds overly challenging, you could consider other issues related to drinking water quality. There are some potential ideas here: http://www.sciencebuddies.com/science-f ... ?ia=EnvSci

With respect to variables, you really only need one independent and one dependent variable. More info is available here: http://www.sciencebuddies.com/science-f ... bles.shtml

Chris

thanks
ok, i have a different question, but it doesn't really connect to what I want to do.
Here it is:
Is it possible to determine the amount of mercury found?

Hi Blueswim, Do you mean detecting mercury in water or other areas of the environment? If you could find an environmental lab to help you, that would be great. I think (I'm not an environmental chemist) you would need some sophisticated equipment to get precise measurements. Maybe a mass spectrophotometer? I will do a little digging and see if I can find some resources for you.

Thanks for the help! i meant mercury in the ground.

Hi,
Yes, it is possible. Here is one procedure for extracting mercury from soils and analyzing using a portable analyzer:
http://www.sdix.com/PDF/Products/Mercur ... cedure.pdf
Here is an example of a large study looking at mercury concentrations in sediment, as well as in water and in fish.
http://nh.water.usgs.gov/projects/nawqa/sw_merc.htm
Here is a discussion of general issues of mercury in the environment:
http://www.usgs.gov/themes/factsheet/146-00/

Good luck!
Chris

Dear Blueswim, It looks like ChrisG found some information for you. I didn't know portable instruments for detecting heavy metals exsisted, so I learned something too. Good luck with your project.