I am using a Parr 1109A Semi-micro oxygen combustion bomb to analyze energy content of my samples. However, during the calibration of the calorimeter, we have found that our benzoic acid standard is not completely burning. We have been inserting approximately 50-60 mg of benzoic acid under 25 atm of pressure with 10 cm of fuse wire. We are performing the experiment on the lab bench for now just to see if we can get the sample to completely burn. When we take off the lid, there is usually a black residue on the side or on the bottom of the bomb. How can we design this experiment so that our benzoic acid standard burns completely?
The recommended practice is to calibrate the Parr 1109A semi-micro oxygen bomb calorimeter with ¼ inch diameter pellets having 0.200±0.020 g of 'calorific grade' (high-purity) benzoic acid. Of course, enough oxygen should be admitted to entirely burn the pellet.
The reason why we have been doing 50-60 mg is that my unknown samples are going to be around this weight. We are trying to calibrate the calorimeter for small amounts of sample and thus, need to burn in the 50-60 mg range. We have increased the atm inside the bomb to 30 but that still did not obtain complete combustion of 60 mg benzoic acid.
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