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Engineering Entrance Exams

100g of water is heated from 30ºC to 50ºC. Ignoring the slight expansion of the water,the change in its internal energy is (specific heat of water is 4184J/kg/K

Profile image of nikhil
12 Years agoGrade
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2 Answers

Profile image of Saurabh Koranglekar
6 Years ago
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Profile image of Vikas TU
6 Years ago
On ignoring the slight expansion of the water, the change in its internal energy is 8.4 kJ.
Given-
Weight of water = 100 gram
Initial temperature = 30 °C
Final temperature = 50 °C
Specific heat of water = 4184 J/kg/K
In this case work done is zero.
W = PΔV and ΔV = 0 so W = 0
We know that change in internal energy is
ΔU = mCΔT
where m is the mass, C is the specific heat and T is the temperature.
By substituting the values we get
ΔU = 100 × 10⁻³ × 4184 × (50 -30)
ΔU ≈ 8.4 kJ

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