Calculate the entropy change when a. two moles of H2O(g) are cooled irreversibly at constant p from 120°C to 100°C. b. one mole
of H2O(g) is expanded at constant pressure of 2 bar from an original volume of 20 L to a final volume of 25 L. You can consider the gas to be ideal. c. one hundred grams of H2O(s) at -10°C and 1 bar are heated to H2O(l) at +10°C and 1 bar.
1 answer:
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Answer:
Explanation:
a )
m = m₀
m is mass after time t . original mass is m₀ , λ is disintegration constant
λ = .693 / half life
= .693 / 1590
= .0004358
m = m₀
b )
m = 50 x
= 40.21 mg .
c )
40 = 50
.8 =
= 1.25
.0004358 t = .22314
t = 512 years .
Answer : The metal used was iron (the specific heat capacity is ).
Explanation :
In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.
where,
= specific heat of unknown metal = ?
= specific heat of water =
= mass of unknown metal = 150 g
= mass of water = 200 g
= final temperature of water =
= initial temperature of unknown metal =
= initial temperature of water =
Now put all the given values in the above formula, we get
Form the value of specific heat of unknown metal, we conclude that the metal used in this was iron (Fe).
Therefore, the metal used was iron (the specific heat capacity is ).