Where can I find these items for my science fair project?

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Where can I find these items?

baryta water (barium hydroxide 0.025 M)
0.01 M hydrochloric acid
Phenolphtalein indicator

I wanted to do an experiment like this one:

www-saps.plantsci.cam.ac.uk/osmoweb/baryta.htm

Thanks so much

[Lise Byrd]

You can go to http://www.enasco.com/science . Click on Chemistry in the list on the left, then Chemicals. You can choose from various indicators, and chemicals are given in alphabetical order. You don't need to worry about the specific molarities of the solutions (although if you can find them, great!) because you can always dilute a higher molarity to a lower one.

I can also ask my chemistry teacher where he gets his chemicals-- he should know of a reliable supplier. Post a reply to let me know, and I will ask him.

Also, if you do end up getting solutions of higher molarity than you need, be very careful diluting them, because they are corrosive. I know from experience that they will burn A LOT if you get any on your skin.

Sonia

[donnahardy2]

Hi,

I don't know where you are located, but I always get my chemicals for science fair projects at Bryant Labs in Berkeley. Their phone number is 510-526-3141 and their address is 1101 5th St, Berkeley, CA. Not all chemical suppliers will sell to private individuals, so you will have to have your parents set up an account number, so they will know whom they are selling to. If the chemical can be used for manufacturing drugs, you won't be able to buy it at all. I'm always surprised at what I can and can't buy. If you are not close to Berkeley, then look for a local chemical supplier and call them and ask if you can buy their products.

If you can't locate a source of these exact chemicals, or if they are very expensive, you can use acid purchased from a pool supply company and substitute calcium hydroxide for the barium hydroxide. Calcium hydroxide is found in some brands of antacids. If your school has a pH meter you can use, you could use that to titrate to pH 7 instead of using the phenolphthalein indicator.

Lise's precaution is very important. You will be working with strong acids and bases to make the dilute solutions for your experiment, so you need to be very, very careful.

When you are planning the details of your experiment, be sure to calculate the amount of CO2 per weight unit of plant material. You will need to weigh the plants used in the experiment and then present results as "CO2 produced per 100 grams," or something similar. Also, if the plants are exposed to sunlight, you need to remember that they will be able to use the CO2 to make sugar. Prepare your solutions very meticulously, because you will probably be trying to measure very small differences in CO2 production. It's probably better to prepare a large quantity of the baryta water and acid for titrating, so you can do all of your testing with one batch of chemicals.

And finally, when you are writing your background section of the science fair project, be sure and explain the chemistry of the reaction you are using the measure CO2 production. The carbon dioxide dissolves in the barium hydroxide solution and forms carbonate ions. The barium precipitates with the carbonate to form the insoluble barium carbonate. You will probably see a fine, while precipitate (BaCO3) at the bottom of the solution, so carefully decant (pour slowly) the clear solution into a separate container for the titration and do not include the precipitate. You will be titrating only the remaining hydroxide ions remaining in solution.

If you really want to impress the science fair judges, do you experiment in duplicate, or even triplicate so you can present data to show the validity of your experiment.

This looks like a great project! Let us know if you need any more information.

Donna Hardy

[hiramuzammal]

You can also order the chemicals through Fisher Scientific:
https://www1.fishersci.com/index.jsp
(you may need to ask your teacher to place the order)