n = m / M ; c = n / Vn: mol; m: g; M: g·molâ»Âč; V: L; c: mol·Lâ»Âč.
Use when: Use the molar mass of the form actually weighed, including its water of crystallization.
Solution preparation
Connect a weighed mass, a amount of substance and the final volume of the solution.
What is happening?
Dissolving consists of dispersing a solute in a solvent until a homogeneous phase is obtained. The concentration depends on the final volume of solution, not just the volume of water added.
A dilution preserves the quantity of solute transferred. We choose a pipette for sampling and a volumetric flask to determine the final volume; the mixture must be homogenized after adjustment.
The formulas, with their conditions.
câVâ = câVâcâ, câ: concentrations in the same unit; Vâ, Vâ: volumes in the same unit.
Use when: Dilution without reaction or loss of solute.
Where is this principle used?
Control laboratory
Prepare assay standards and reagents.
Pharmaceutical or water treatment plant
Prepare controlled concentration solutions.
What to observe in the experiment
Prepare a tenth dilution: choose a final volume ten times larger than the volume taken and predict the concentration obtained.
References and readings
This sheet explains the principles and their assumptions. Educational simulation can simplify the process; an industrial model requires suitable data and validation.
Have you understood the essentials?
Only one correct answer per question. Answer all three questions, then view the answer key.
Intu Lab · Understanding sheet · Kimba Christian