gravimetric analysis
/ grav-ih-MET-rik /
Imagine wanting to know how much sugar is hidden in a fizzy drink, but instead of trusting a meter, you find a way to turn that sugar into a solid, scoop it out, dry it, and simply weigh it on a balance. That patient 'catch it, weigh it' approach is the heart of gravimetric analysis.
More precisely, gravimetric analysis measures how much of something (the analyte) is present by converting it into a pure, weighable form — usually an insoluble solid — and then determining its mass. From that mass and the known chemistry, you calculate the amount of analyte in the original sample.
It matters because weighing is one of the most accurate operations a lab can perform, so a well-run gravimetric determination can be extremely reliable, needing no calibration curve. The catch is that it is slow and demands care: every grain lost or impurity gained shows up directly in the answer.
To find the sulfate in a water sample, you add barium chloride so that solid barium sulfate forms, filter and ignite it, weigh the white powder, then work back to the mass of sulfate originally present.
Turn the analyte into a clean solid, weigh it, then calculate backwards.
Gravimetry is an absolute method: it relies only on mass and known molar masses, so no reference standard solution is needed. That independence is its biggest advantage over most instrumental techniques.