Talk:Percentage solution

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Not knowing anything, I would have naively assumed that a 1% solution is a mixture of 1g of solute and 99ml of solvent. AxelBoldt 01:27 Apr 14, 2003 (UTC)

That would make sense if 1g had a volume of 1ml. In that case you would have a % v/v solution. Howver for a w/v (weight/volume) there is little point in only having 99mls of solvent, since most solutes don't have 1g/ml density. Theresa knott

I think it should be mentioned that a % w/v solution is somewhat of a mathematical impossibility. Since weight and volume are measured in different units, a w/v ratio can never be specified unitless as per cent. The appropriate unit would rather be kg/m³ or something similar. w/v does not make sense unless units are also specified. This unit is, however, mainly used within the fields of biology and medicine, by people that rarely have the mathematical knowledge to even notice this flaw.

Yep these solutions are approximate. When a biologist wants an exact solution they use molarity the same as everyone else. Theresa Knott | Taste the Korn 10:54, 17 February 2006 (UTC)

These solutions are not more approximate than a molar solution; that only depends on measurement precision. They are, however, not suitable to be described as percentage solutions, but rather using an appropriate unit. Unfortunately this highly ambiguous notation is too often used in biology and medicine as well as in chemistry (less common, though). But as these are mostly my own views I am not sure if it is really appropriate for me to make too much of a deal out of it in the article. It would on the other hand be interesting to hear someone who actually uses this (incorrect) notation motivate its use.

User AxelBolt is actually correct if the solvent is water. The convention is, when no units are specified, it is w/w. A m/v solution should specify the units, as someone already wrote; although it is often not specified, and is often assumed to be g/mL (or equally, kg/L). Further, the notion that a 10% w/v solution is prepared by mixing 10 g of solute with 100 mL solvent is wrong. A 10% w/v solution is prepared by mixing 10 g of solute with enough solvent to make 100 mL of solution. The first method will yield a solution that is only approximately 10% w/v. For this reason, "w/v" should not link to this article, but to concentration instead. As for "percentage solution" as currently defined by this article, is this just a common mistake or is it really defined by biologists as such?--141.154.46.140 04:33, 18 May 2006 (UTC)