Standard solutions are solutions of known concentration, they can be either primary or secondary standard solutions

Primary Standard Solutions

Primary standard solutions are prepared from a known quantity of a primary standar, they are made using a volumetric flask filled with water

Primary standards are pure substances

Criteria for a Primary Standard:

4 Characteristics:

1) Pure w/ a known formula
2) Soluble in water
3) Stable, meaning it does not:
react with itself (decompose) e.g. $\sf\small KMnO_4$
react with chemicals in the air e.g. $\sf\small NaOH
react with water, meaning it is not:

deliquescent (does not absorb moisture from the air) e.g. NaOH
hydroscopic () e.g. HCl
efflorescent e.g. Na ₂CO₃.10H₂O.

4) High molar mass (decreasing random error)⇒ weighing scale does not accurately or consistently show mass (rounds up/down)

This leaves 2 suitable compounds:

NaCO₃
H₂C₂O₄.2H₂O (the H₂O increases molar mass)

Secondary Standard Solution

⇒ Solution whose concentration is established by reacting it with a standard solution (”standardising”) Secondary Standards are obtained through titration

ATAR Survival Guide

Volumetric Analysis

Theory

Volumetric Analysis and Standard Solutions

Worksheets

Quizzes & Flashcards