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Buyer Beware! :)
20 August 2010
My plan was to allow the limestone to dissolve in the vinegar solution for a couple of days in order to create the buffer solution. Well other things came up (i.e. work) and I didn't look at the solution for a couple of weeks! 
When I tested the solution, the pH and density indicated that it wasn't diluted to 7%. Something weaker. So I borrowed the family chem set and did a titration to find out what I bought! There wasn't a label on the vinegar I bought but I was told 3 parts water to 1 part vinegar for pickling. I wanted to believe that you pickle with store bought vinegar (5%) so that meant I was buying 20%.
The titration indicated that I had purchased 4 gallons of 5% vinegar!
So my "7%" buffer solution is actually about 1.75%!
While this is weaker than desired but according to the Jeppson paper there is no harm in weaker acid other it takes longer to dissolve a sample. The important point is to start with a pH > 3.6. Not wanting to throw it out and pay a lot more for 20%, I'm going to proceed making up several acid baths with the buffer solution and the vinegar. I should be able to blend portions of vinegar, buffer solution and water to create a bath at pH = 3.6.
When I tested the solution, the pH and density indicated that it wasn't diluted to 7%. Something weaker. So I borrowed the family chem set and did a titration to find out what I bought! There wasn't a label on the vinegar I bought but I was told 3 parts water to 1 part vinegar for pickling. I wanted to believe that you pickle with store bought vinegar (5%) so that meant I was buying 20%.
The titration indicated that I had purchased 4 gallons of 5% vinegar!
So my "7%" buffer solution is actually about 1.75%! While this is weaker than desired but according to the Jeppson paper there is no harm in weaker acid other it takes longer to dissolve a sample. The important point is to start with a pH > 3.6. Not wanting to throw it out and pay a lot more for 20%, I'm going to proceed making up several acid baths with the buffer solution and the vinegar. I should be able to blend portions of vinegar, buffer solution and water to create a bath at pH = 3.6.
