Question

Burns produced by steam at 100°C are much more severe than those produced by the same mass of 100°C water. To verify this:

(a) Calculate the heat that must be removed from 4.00 g of 100°C water to lower its temperature to 48.0°C.
  kcal
(b) Calculate the heat that must be removed from 4.00 g of 100°C steam to condense it and lower its temperature to 48.0°C.
  kcal
(c) Calculate the mass of human flesh that the heat produced in each case can raise from the normal 37.0°C to 48.0°C. (Flesh is badly damaged at 50.0°C.)
steam
  kg
water
kg

Answer 1

The heat that must be removed from the water is mcdI (4.00x10 (1kcal/kg'c)100-48) -0.21 kcal The heat that must be removed for the steam is mcdl = (4.00× 10-3) (0.48 kcal/kg°C) (100-48) -0.099 kcal The mass of the human flesh for the water system is, O mcdI 0.21- m(1 kcal/kg c)(48-37) m = 0.019 kg The mass of the human flesh for the steam system is, Q = mcdT 0.099 m(0.48 kcal/kg°C)(48-37 m 0.0187 kg