Final answer:
The question appears to relate to calculating the potential difference or atomic weight, however, due to a lack of clear context or direct correlation with the reference materials provided, a precise answer cannot be given without more information.
Step-by-step explanation:
The question seems to be partially inferred as it has a typo or incomplete information, specifically 'AV115,2.5a'. We could interpret this as a request to calculate the potential difference (AV) between two points (which might be separated by a distance 2.5a) given certain values, or possibly the atomic weight (given numbers like 112 and 115) of an element. However, the details provided in the references do not directly relate to calculating potential difference nor give a clear context to compute a value that corresponds to 'AV115,2.5a'. As no clear correlation is shown between the reference materials and the question, it's not possible to provide a precise answer. If 'AV' represents atomic volume, atomic weight, or another specific concept from physics or chemistry, please provide more context for an accurate calculation.