When air is inhaled, it quickly becomes saturated with water vapor as it passes through the moist upper airways. when breathing dry air, about 25 mg of water are exhaled with each breath. at 12 breaths per minute, what is the rate of energy loss due to evaporation? at body temperature, the heat of vaporization of water is lv=24×105 j/kg?

m = mass of water evaporated = 25 mg = 25 x 10⁻³ g = 25 x 10⁻³ x 10⁻³ kg = 25 x 10⁻⁶ kg

L = latent heat of fusion of water to vapor = 24 x 10⁵ J/kg

n = number of breaths in a minute = 12

Heat lost in a breath is given as

q = mL

Total heat lost in a minute is given as

Q = nq

Q = nmL

inserting the values

Q = (12) (25 x 10⁻⁶) (24 x 10⁵)

Q = 720 J/min

frequency or wavelenth of em radiation in a vacuum