Science Buddies: "Ask an Expert"

I had a quick question regarding the molarity of the Phosphate Buffer Solution. The materials list simply said Phosphate Buffer Solution, pH 7, 500 mL. I needed to know the molarity of the solution/concentration before we make it or get it from one of the local colleges. Thanks!

Shanta

Hello, Shanta,

I looked at the information on Amazon and on the manufacturer's site: http://www.coleparmer.com/Product/Cole_ ... raceable_r.

Since the molarity is not listed in either place, I suggest that you directly contact Cole-Parmer: http://www.coleparmer.com/Contact. You should get a response within 3-5 business days (as their website says), but if you need the materials sooner, perhaps a call would be better. Hope that helps! Good luck!

Hi,

Goldernzenith has given you a good suggestion, since the concentration of the phosphate buffer is not on the Amazon or the Cole Parmer webistes. If you are in a hurry, you can also call the Cole Parmer toll free number 1-800-323-4340 tomorrow after 7 am Central Time. Be prepared with the Catalog number that you are inquiring about. If you can find out what the concentration is, let us know the description (monobasic or dibasic) and formula weight of phosphate buffers salts you have available if you need more help.

Donna Hardy

I'm not a chemist, but I did find a "recipe" that might work that you could make in a chemistry lab.


Standardization buffers

For pH=7.00 :
Add 29.1 ml of 0.1 molar NaOH to 50 ml 0.1 molar potassium dihydrogen phosphate.

Alternatively :
Dissolve 1.20g of sodium dihydrogen phosphate and 0.885g of disidium hydrogen phosphate in 1 liter volume distilled water.

I hope that this or the help of our other experts will help. Let us know how it turns out. I apologize for the lack of clarity in the project guide; we will remedy that as soon as we can.

Thanks for all the help everyone! I did some more research online and I found an article from MIT about the original experiment which used 0.1 M Potassium Phosphate buffer. I will be getting that from one of the local colleges. Thanks anyway!

Shanta