Introduction
This Application Note is the second in a series relating to the eQCM 10M™ and assumes that
you have read and understand the material covered in the Application Note, Basics of a
Quartz Crystal Microbalance.
The purpose of this Application Note is to show the reader a simple experiment where we
reduce Cu2+onto an Au electrode and then oxidize Cu back off. We will then use the result to
calculate a calibration factor for the crystal. Conversely, we will show you how to calculate the
molar mass of the species deposited using a calibration factor.
Each crystal has a theoretical calibration factor, however, under typical experimental
conditions, these calibration factors will vary slightly. We will use Cu2+ to calculate a
calibration factor which could then be used in subsequent experiments on the same crystal.
Cu2+ is reduced in a two electron reaction as shown below:

CuSO4(aq) + 2 e- →Cu(s) + SO42-(aq)
Our goal is to reduce Cu2+ onto an Au electrode, then use the frequency decrease and the
charge passed to calculate a calibration factor.