[alt-photo] Re: Math mystery

[Johnny Brian]

I think this is easier to solve by calculation of the amount of solute required. A 3% solution is 3gm per 100ml (3/100= 3%), or 30gm per 1000ml. A 37% solution has 370gm/1000ml, or 0.37gm per ml. For 30gm of solute, 30/0.37=81ml, so 81ml of 37% diluted to 1L is 3%. 

Johnny Brian

On Feb 28, 2013, at 13:30, Jacques Kevers <jacqueskv at gmail.com> wrote:

> Hi,
> I have a problem to understand the math behind this (related to making a
> hardening solution with formalin):
> "Add 25ml of formalin to 1,000ml of distilled water which makes a 3%
> formalin hardening solution."
> I mean, even if the formalin is 100% pure, 25 ml on 1000 is only 2.5% ,
> right?
> So, when using a 37% solution of formalin, I would think that you have to
> use around 80ml of the formalin solution...
> What am I missing?
> Thanks,
> Jacques
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