1. The problem statement, all variables and given/known data Compare the electrostatic energy of two opposite charges e and -e, a distance 7 angstroms apart in water at room temperature and that in vacuum (express the energy in terms of Bjerrum length) 2. Relevant equations E = 1/(4(p[itex]\pi[/itex][itex]\epsilon[/itex]D)*(-e^2)/r^2 ??? 3. The attempt at a solution First of all is this the right equation to use? If so, is the Bjerrum lenght the distance between the charges? And for a vacuum is the dialectic constant (D) just 1?