Ammonia is a toxic gas of chemical composition NH3. "Household"
ammonia is not in the form of the gas but is actually ammonium
hydroxide of chemical composition NH4OH. The gas is dissolved in
water. The ammonia molecules each bond with one hydrogen atom from
the water molecules, producing lots of positive Ammonium (NH4+) ions
and lots of negative Hydroxide (OH-) ions. Household ammonium
hydroxide is typically 10% ammonia by weight.
If you wanted to change your 25% "technical" ammonium hydroxide to
10% ammonium hydroxide as in the household ammonia concentration,
you would add more water using the following formula:
Original concentration X Original volume = New concentration X New
where the new volume is the unknown in the equation.
For example, if you started with 100 ml of 25% ammonium hydroxide,
and wanted to get to 10%, you substitute the numbers to find out how
much water to add, thus:
0.25 X 100 = 0.10 X ?
? = 0.25 X 100 / 0.10
? = 25 / 0.10
? = 250 ml
Therefore you would need to add an extra 150 ml of water, making the
volume up to 250 ml to achieve a concentration of 10% ammonium
I hope this helps.