[bdickson]

I need help determining a multiplier for a given concentration based on the number of drops. For example, I have a customer using an acid based cleaning compound and typically we give the customer a concentration range between 1 - 10%. Normally the customer would count the number of drops to turn the solution from clear to pink, then compare the number of drops to the chart for the concentration. However, my customer wants a multiplier for determining concentration instead of comparing the number of drops.  That said, my customer titrates the solution using 2N Sulfuric Acid through a dropper method (counting drops) and phenolphthalein as my indicator. How do I come up with a predetermined multiplying factor which I could mulitiple times the number of drops which would equal my concentration.

Please help as I have many of these solutions with different concentration ranges. There has got to be set method for determining different multipliers?

[Borek]

To be honest I am a little bit lost as to what your question is. If I understand you correctly you are asking about ways to convert between concentrations expressed using different units and determined using volumetric method (in this case acid-base titration). These are the very basic things, covered in a basic chemistry courses - you need to know what the concentration is, and what are calculations behind the concentration determination.

See these pages:
http://www.chembuddy.com/?left=concentration&right=toc
http://www.titrations.info/titration-calculation

[Arkcon]

You apparently want to use drops to measure volume for a titration, for some OEM application.  OK, but ... that doesn't depend just on the concentration of the liquid in the bottle.  You also have to consider the fluid dynamics of the bottle -- how much it holds, how big the hole is, how hard will people squeeze, how the surface tension of the fluid will hold the liquid together until the drop breaks free.  There's nothing terrible with the "drops" method of titration to an endpoint, but the answer will never be as accurate or precise as using real volumes measures using analytical glassware.  The best you can do is try it multiple times and see how close you can get, compared to doing it analytically.