Hydrogen Peroxide Fun

In the closing weeks of my research experience, Dr. Cooke tasked me with finding a procedure for determining the actual percentage of hydrogen peroxide that was in a sample.  The hydrogen peroxide was used in cleaning to prepare an algal sample for imaging under a scanning electron microscope.  Very small amounts of the hydrogen peroxide (30%) are actually used in the cleaning and so I had been using a smaller sample separate from the larger container.  This container went through multiple cycles of heating and cooling, so it was natural to ask whether the amount of hydrogen peroxide is comparable to the apparent starting value of 30% by volume or if the sample had degraded significantly after the heating cycles.

I used a method for determining the amount of hydrogen peroxide by exposing a small amount of the hydrogen peroxide (1 mL) to a catalyst to accelerate the rate of decomposition of the 1 mL of hydrogen peroxide into more stable products, water and oxygen.  The oxygen gas that was released by this process was collected and fed into a graduated cylinder that was inverted in a container of water.  As the amount of oxygen gas increased, it displaced the water in the graduated cylinder.  From this volume of oxygen gas, the amount of moles of oxygen could be calculated which correlates to twice the amount of moles of hydrogen peroxide.  There were several issues with performing this experiment.  The first was finding a suitable catalyst so this could be carried out in an minutes rather than days. Another was finding the proper equipment to capture the oxygen.  Everything that I found that should have worked leaked in some fashion.