For a K+–Cl- ion pair, attractive and repulsive energies EA and ER, respectively, depend on the distance between the ions r, according to

Answer charle's law

Answer/when the cell uses energy;

For lesson: cameras, plant presses, newspaper, paper towels, clip boards, pencils, calculators, field guides, metric measuring tapes, paper, transect squares, colored pencils, ph meters, light meters, computers, etc.for extension: baggies for soil samples collecting, distilled water, hand shovels, beakers, boiled rice, microscopes, well microscope slides or regular microscope slides with cover slips