1.

1. 1 g of water at 373 k is converted into steam at the same temperature at normal pressare. Thevolume of 1 em of water becomes 1671 em on boiling. Calculate the change in the internalnerer of the system if the heat of vaporization is 540 cal gT. Ans 2098 Jsrie of heat and

Answer»

here we shall use the first law of thermodynamics

ΔQ = ΔU + ΔW

so, change in internal energy will be

ΔU = ΔQ -ΔW

here,

ΔQ = mL =1g x 540Cal/g = 540 Cal

ΔU = change in internal energy (to be calculated)

ΔW = change in work done

so,

ΔW = pΔV

where

ΔV = 1671cm3- 1cm3= 1670cm3= 1670 x 10-6m3

p = hρg = 0.76 x 13600 x 9.8 ~ 101293 N/m2

so,

ΔW = 101293 x 1670x10-6= 169.16J

or

ΔW = 169.16 / 4.2 = 40.3 Cal

thus, we have

ΔU = 540 Cal - 40.3 Cal

so,

ΔU = 499.7 Cal = 2098.74 J


Discussion

No Comment Found

Related InterviewSolutions