Borax, again

dancqu said:

I and likely Mr. Gainer had percentage in mind. Dan

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I hope that Mr. Gainer agree, too

Kirk Keyes said:

Pat - take a closer look of the graph you posted and check the units on it. While the temp on the x-axis is in degrees Farhenheit, the solubility on the y-axis is given in %w/v. And that's the same as grams/100 ml which equals 10xgrams/liter.

So according to your graph, it should be about 47 grams/liter at 20C...

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The chart is correct. I read it wrongly. The solubility according to CRC handbook is 2% (2 g/ 100 ml) at 0 C, which is 32 F. The chart was from the manufacturers and applies to the decahydrate. It is not always certain that the Borax you have is all decahydrate because it is subject to change due to humidity. You can be sure that if you have a saturated solution of either the decahydrate or the tetrahydrate or a combination, the percentages on the chart show the equivalent weight of decahydrate per 100 grams of solution. If you feel the need for precision, make a saturated solution at some higher temperature than your storage temperature. When you need borax, measure the temperature of the solution and calculate from the chart weight of solution that will give you the amount of borax you need.

Kirk Keyes said:

Not graphs, but usually solubility at 0C, 20C, and 100C, CRC Handbooks of Chemistry and Physics or even Lange's Handbook of Chemistry. I prefer the older CRC Handbooks from before 1960 or so where they are truely handbooks instead of huge deskbooks. You don't need all the X-ray crystallography data and other stuff from the newer (post 1960) books. I have a 32nd edition from the 50s that I like. They often have tables of more common inroganic chemicals with solubility vs. temp. But not photo specific...

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Until I can buy one of these (expensive) books, would you mind to look up the three values for boric acid (granular) for me?

I happen to have a 16th Ed. CRC Handbook from 1931 here and it says Boric acid has a solubility of 1.95 g/100ml at 0C and 29.1 g/100ml at 102C. It also says that 0.24 g/100ml in ethyl ether at 0C, 28 g/100ml in glycerine at 0C, and it is slightly soluble in ethyl alcohol.

Kirk Keyes said:

I happen to have a 16th Ed. CRC Handbook from 1931 here and it says Boric acid has a solubility of 1.95 g/100ml at 0C and 29.1 g/100ml at 102C. It also says that 0.24 g/100ml in ethyl ether at 0C, 28 g/100ml in glycerine at 0C, and it is slightly soluble in ethyl alcohol.

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Thanks

This verifies my experience. I tried to dissolve 7.5 g in 50 ml at 60C and was not able to. Dissolving the same amount in 80 ml at 90C worked instantly. I just wondered what the limit at 60C would be.

Kirk Keyes said:

I happen to have a 16th Ed. CRC Handbook from 1931 here and it says Boric acid has a solubility of 1.95 g/100ml at 0C and 29.1 g/100ml at 102C. It also says that 0.24 g/100ml in ethyl ether at 0C, 28 g/100ml in glycerine at 0C, and it is slightly soluble in ethyl alcohol.

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Mine is from 1977-1978. I once had access to a 1957 edition that I liked better because it had photo formulas and other "homey" information.