# chemistry help

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I need to make up an aqueous solution that is 25% PO4-3 ions by weight.

I have Klean Strip Phosphoric acid from Home Depot. The MSDS states it is 75 to 80% phosphoric acid. How much of this would I put in one gallon (8.3 lb.) of water?

Same question for nitric acid. Here I have 30% acid and need 1% NO3-1 ions by weight.

This doesn't eed to be hyper exact. I want to get it to a cook book type direction. Example add 4 cups Klean strip to 10 cups water then add .5 cup nitric acid.

I would have flunked engineering chemistry in '72 if it weren't for a cute girl that needed help with engineering physics. We helped each other, sat side by side at every test. Teamwork.

Karl

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Where did you get nitric acid?

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Mark level of 1 gallon distilled water. Discard 3/8 gallon water. Add 3/8 gallon phosphoric acid to mark.

Dilute a portion of the acid by a factor of 30

For example, add 1 ounce of acid into a volume of 29 ounces of water.

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Ignoramus20025 fired this volley in news:5a-dnY26WJr7A9DTnZ2dnUVZ snipped-for-privacy@giganews.com:

This isn't really a chemistry question, except that you need to know enough about it to realize that most dilutions, if stated in percents, are weight-to-weight, and you need to know what the NO3 radical and HNO3 molecule weigh.

Pure HNO3 is 63 units total weight (grams, if in moles), with 62 parts in the NO3 radical.

So it's not 100% NO3, but .984 NO3-. 30% dilution means 3.3333 parts of solution for 1 part of pure, then divide by .984 to get 3.3875 parts of the diluted acid to get 1 part of NO3 radical.

Remember, though, you're adding 2.37 parts of water with that 3.3875 parts of dilute acid.

So... 100 parts of water to 3.3875 parts of dilute acid gives you

102.37 parts water and 1 part NO3-. That works out (1/103.37) or a .96% solution (ninety-six one-hundredths of one percent).

That's a 4% error, and not great. Divide the acid amount by .96 = 3.53 parts... add it up again. 102.47 (.four-seven, now) parts water to

1.059 parts NO3 radical. 1.059/103.52 or 1.02%

That's a 2% error. You can halve it with each iteration, but 2% of the target (probably even 4%) would be close enough for most reactions.

This wasn't much of a chemistry question, but a proportioning question, except for the matter of how much NO3 radical weight is in each 'part' of pure acid.

It would have been best solved by simultaneous solution of equations, but successive approximations are easier for most of us math-impaired, and better suited to algorithmic solutions.

The specific gravity of 30% HNO3 is 1.12.

So, add 3.53/1.12=3.15 volumes of 30% acid to each 102.47 volumes of water. Scaling --- 3.0758 volumes of 30% acid to 100 volumes of water.

LLoyd (hope my arithmetic was right! )

LLoyd

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Where can I get nitric acid?

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Ignoramus20025 fired this volley in news:ZIGdnRCwQ9mJLdDTnZ2dnUVZ snipped-for-privacy@giganews.com:

For small quanities, you can get 70% from

There are LOTS of other sources, as it's a common industrial chemical.

LLoyd

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I got it on eBay

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Thanks, i was trying to make this harder than it was.

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Thanks, exactly the kind of answer i needed.

Karl

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"Lloyd E. Sponenburgh" fired this volley in news:Xns9F45D4BF367BAlloydspmindspringcom@216.168.3.70:

Also, Ig,

You'll have to contact him, he doesn't list it.

Shipping is stupidly expensive on HNO3, because it cannot be shipped in the same box with just about anything else.

LLoyd

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Any laboratory supply company should stock it, usually in Winchesters, which is how I used to buy it. I usually used 20 Winchesters of Sulphuric acid and 10 of Hydrochloric acid for each one of Nitric.

Alan

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