Living cells "pump" singly ionized sodium ions, Na+, from the inside of the cell to the outside to maintain a membrane potential V membrane=Vin V out= -71mV It is called pumping because work must be done to move a positive ion from the negative inside of the cell to the positive outside, and it must go on continuously because sodium ions "leak" back during the cell wall by diffusion.

1. How much work should be done to move one sodium ion from the inside of the cell to the outside?

2. At rest, the human body uses energy at the rate of approximately 93W to maintain basic metabolic functions. It has been estimated that 24{\rm \\%} of this energy is used to operate the sodium pumps of the body. Estimate to one important figure the number of sodium ions pumped per second.