How can I get water samples with pHs of 0-14??

[G50]

My son and I are trying to figure out how to get 15 water samples, one each from 0-14. For a science experiment.

We tried mixing with acids and bases to adjust the pH.

But the problem is accurately measuring.

The test strips we used can distinguish roughly between an acid, base and neutral, but eyeballing color differences is impossible to get accurately for 15 levels.

We bought a digital ph tester off ebay, but that was a joke.

Are there any superaccurate test strips?

Can some kind of a lab do this for us, at a reasonable cost?

Can the hydroponics store down the street help?

[VincentVega]

I use test strips to test my well and pool water, range is ~4-10 I think. I'm sure you have a pool or water place nearby and they'll be able to help.

[E38Driver]

You can go to the hydro store and get reference samples like those that are used to calibrate your pH meter. That is also the best way to determine the pH of a solution.

Dave

[stomachmonkey]

Go to your local university.

If they don't have the answer or the equipment that you need then it either does not exist or is not possible.

It's important for your son to do the talking about "his" experiment.

[aigel]

You can order calibration samples from chem supply houses but they are pricey and not likely available for each Ph value. You won't have "water" on the higher and lower numbers, rather than strong acid and bases. Especially the alkaline side is dangerous - do not let the kid handle any without supervision and proper personal protection equipment.

For a meter, you will have to spend some $.
https://us.vwr.com/store/catalog/product.jsp?catalog_number=74730-030

Can you tell us more about the experiment?

Why not use naturally occuring / household chemicals to test with a Ph meter? Citric acid, drano, vinegar, battery acid etc.

HTH?

G

[G50]

Thanks for the suggestions.

As you suggested, aigel, we were able to calibrate the ph meter using household items (vinegar and milk!).

Once adjusted, it was spot on for the specs for those 2 items, and it was good to go.

He's only in 9th grade, so I do need to supervise the handling of the very concentrated HCL acid and powder base (lye) that he's using to adjust the ph levels.

[Geneman]

G50 I am a scientist and i did this with my 10 year old son last year. I used a magnetic stir plate and a digital pH meter hat could read in real time. nstead of H2o we used a simple solution of Phenolthalein red indicator. As you titrate it up and own with acid or base it changes from clear-orange - deep red the chicks loved it!!! Very simple nd clear demonstration and the pH is read out during titration. (unfortunately, we were beat out for 1st prize by a homemade hovercraft made with a leaf blower..oh well)

let me know if you need some more details... ps the white lab coat was primo with the girls also!

i can send let you borrow a pH machine and stir plate if you promise to send it back email me: rauscher@wistar.org

Frank

[vash]

Originally Posted by Geneman

G50 I am a scientist and i did this with my 10 year old son last year. I used a magnetic stir plate and a digital pH meter hat could read in real time. nstead of H2o we used a simple solution of Phenolthalein red indicator.

(ahem...you mean your kid did all these things.)

hah..the experiment sounds cool. i built a model illustrating the different sea bed levels..it was very lame. it was very obvious an no adult touch this thing

we all got our butts kicked by a kid (or her dad) that boiled a chicken clean and rebuilt the entire skeleton..it was effen slick!! she made a drawing labeling key bone structures.

[aigel]

Originally Posted by vash

we all got our butts kicked by a kid (or her dad) that boiled a chicken clean and rebuilt the entire skeleton..it was effen slick!! she made a drawing labeling key bone structures.

Here is a nice thing to try with your first chicken you are going to slaughter!

Very cool project. I - aehm - my kid should do that for the next science fair!

Maybe a bigger animal would be better = I am going bear hunting soon.

G

[M.D. Holloway]

Calling Carl Fischer...actually testing the pH is easier than making a solutions that approuch 1 or 14. Dangerous stuff!

[vash]

Originally Posted by aigel

Here is a nice thing to try with your first chicken you are going to slaughter!

Very cool project. I - aehm - my kid should do that for the next science fair!

Maybe a bigger animal would be better = I am going bear hunting soon.

G

i would love a do-over..

a bear would be fantastic. i would add info on bone growth. easy A!

[sammyg2]

I've messed with some nasty stuff over the years, including alien acid (HF).
But I've never seen anything with a PH below 1.

Is that even possible?

[G50]

Originally Posted by sammyg2

I've messed with some nasty stuff over the years, including alien acid (HF).
But I've never seen anything with a PH below 1.

Is that even possible?

He's had no problem getting to a pH of 0.0 by just adding (a surprisingly small) amount of hydrocloric acid to water.

The harder part is getting pH above 12.8 or so. He's using sodium hydroxide (also called lye?) and it doesn't seem to get past 12.8.

[nostatic]

You'll want to make buffer solutions - trying to do it with pure water won't work well (or at all). Some info here:

Preparation of pH buffer solutions