# Accuracy refers to the freedom from error or mistake of a measuring device. How accurate is a volumetric flask as a measuring instrument?

Sep 4, 2016

The accuracy of a volumetric flask depends on its capacity.

#### Explanation:

Volumetric flasks come in two classes, and in sizes ranging from 1 mL to 6 L.

Class A flasks are used in analytical labs. They are more accurate and must be marked with the letter "A".

Class B flasks are used for educational work or whenever extreme accuracy is not required. Their volumetric tolerances must be within twice the specified Class A tolerances.

They must all be used at their calibration temperatures.

The specifications for some common capacities of Class A flasks are:

$\text{Capacity/mL"color(white)(m)"Tolerance/mL"color(white)(m)"Tolerance/%}$
stackrel(———————————————————)(color(white)(mmm)25color(white)(mmmmmm)0.030color(white)(mmmmm)0.12)
$\textcolor{w h i t e}{m m m} 50 \textcolor{w h i t e}{m m m m m m} 0.050 \textcolor{w h i t e}{m m m m m} 0.10$
$\textcolor{w h i t e}{m m l} 100 \textcolor{w h i t e}{m m m m m m} 0.080 \textcolor{w h i t e}{m m m m m} 0.080$
$\textcolor{w h i t e}{m m l} 250 \textcolor{w h i t e}{m m m m m m} 0.12 \textcolor{w h i t e}{m m m m m l l} 0.048$
$\textcolor{w h i t e}{m m l} 500 \textcolor{w h i t e}{m m m m m m} 0.15 \textcolor{w h i t e}{m m m m m l l} 0.030$
$\textcolor{w h i t e}{m m} 1000 \textcolor{w h i t e}{m m m m m l l} 0.30 \textcolor{w h i t e}{m m m m m l l} 0.030$

Note that the absolute tolerance increases, but the relative tolerance decreases, as the capacity increases.