6.5Other Units for Solution Concentrations
Section · module m68704
What this needs
Learn these first — this section will not make sense without them.
Nothing in the algebra book is a prerequisite for this section.
What this touches
Algebra that turns up here. Not a blocker, but this is where you will see it used.
ppm and ppb are defined by multiplying a mass ratio by 10⁶ or 10⁹, and the worked example chains a ppb→ppm conversion (÷10³) into a gram→microgram conversion (÷10⁻⁶) — misplacing any one exponent produces an answer off by a factor of a thousand or more.
- Applies2.4Models and Applications
The lead-in-tap-water worked example explicitly rearranges ppb = mass solute/mass solution x 10^9 to mass solute = ppb x mass solution/10^9 in symbols ('Rearranging the equation defining the ppb unit and substituting the given quantities yields') before any of the three given numbers (15 ppb, 300 mL, 1.00 g/mL) are substituted — the identical solve-a-formula-for-a-specified-variable step already used for molarity and dilution, now applied to the ppb definition.