And now I know that if you have some bomb ass looking nitrostyrene then a recrystallization will be a waste of time and nerves. Go ahead and just dump it onto the NaBHg like we are about to do in the next step. This link might help as well: https://www.sciencemadness.org/whisper/viewthread.php?
Note that the initial rocket mass, M 0 , is the sum of the propellant mass expelled during the burn, M p , and the final mass of the rocket after the burn, M b .