Hi Sharon,

```
I disagree about the formula being easier to deal with, though, but
that's because math is not my strong suit; I wouldn't be able to
translate my measurements into that formula at all. It's more
precise, certainly, but I find it's easier to just measure out 4
cups of water to 1 cup of nitric (with glass measuring cups,
natch).
```

The beauty of the formula (and the reason I keep harping on about

it), is that it’s a really useful formula for use with any sort of

dilution problem, ie mixing one strength of liquid to another

strength. It really is easy once you get it.

Perhaps one thing which I failed to communicate clearly, is that the

"Final Volume" in the formula, is the total volume of acid

(“Original Volume”) AND water added together, ie the diluted solution

volume. So:

Original Concentration X Original Volume = Final Concentration X

Final Volume

where:

Original Concentration refers to the strength of you acid as

purchased; Original Volume refers to the volume of acid used;

Final Concentration refers to the strength of the solution after the

water has been added;

Final Volume refers to the total volume of the acid AND water added

together (that’s why you need to subtract the “Original Volume” from

the “Final Volume” to calculate the amount of water needed).

The real value of using a formula like the above, is if you purchase

(or are given) really strong acid, and you want to dilute it to a

specific (and quite weak) concentration. Just saying mix four cups

of water to one of acid, will give a very different result for one

person starting with 70% or stronger acid, than it will for the

person using 38% or weaker acid. That’s why I asked people to state

their acid concentration, as such ratios are fine, and accurate

enough if your acid is in the same ballpark, concentration wise, and

you don’t like the maths of using a formula. So if you don’t like the

maths, and someone says “four cups of water to one acid” and they

state 70% strength, at least that way, if your acid is only 38% or

weaker, then you know you only need two cups of water to one cup

acid.

Helen

UK