Burns produced by steam at 100°C are much more severe than those produced by the

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 5.00 g of 100°C water to lower its temperature to 52.0°C.
A: 0.24 kcal (correct)
(b) Calculate the heat that must be removed from 5.00 g of 100°C steam to condense it and lower its temperature to 52.0°C.
_____ kcal (I have tried 18.912, 2.695, and 129.12 ...... none of these were right)
(c) Calculate the mass of human flesh that the heat produced in each case can raise from the normal 37.0°C to52.0°C. (Flesh is badly damaged at 50.0°C.)
steam
_____ kg
water
_____ kg

Please help!

Explanation / Answer

b)heat taken or removed = m*s*t (s is Specific heat and t is temperature difference) and in condensation at 100 C heat removed = m*latent heat

5*540+5*1*48 = 2940 cal = 2.94 Kcal (latent heat of vaporization = 540 cal/g)

c) Specific heat of human flesh = 3.49 J/g = 0.831 cal/g;

Now, heat taken = m*s*t

or, 240 = m*0.831*15

or, m = 19.26 g

and 2940 = m'*0.831*15

or, m' = 235.87 g

b) 2.94 Kcal

c) 19.26 g and 235.87 g

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