Consider a solid with a specific heat of 5.0 J/g degree C and a lent heat fusion

Question

Consider a solid with a specific heat of 5.0 J/g degree C and a lent heat fusion of 100 J/g. A 20-g sample of this material is initially at 8.0 degrees below the melting point. If 1400 J of heat is added to this sample, how much of the sample will still be solid? a. 6 g b. 14 g c. 20g d. 0 g e. This is not possible to answer with the information given. The pressure, temperature, and volume of a sample ideal gas are P, T, and V, respectively. If the volume is tripled and the pressure is halved, the temperature becomes a. 6T b. 3T/2 c. 2 PV d. 2P/(3V) e. 2T/3 If 75 J of heat is added to a gas while the gas performs 50 J of work on the surroundings, what is the change the internal energy of the gas? a. 75 J b. 125 J c. 50 J d. 25 J e. Not enough information to tell.

Explanation / Answer

heat absorbed temp to reach at melting point,

Q1 = 20 x 5 x 8 = 800 J

now energy left = 1400 - 800 = 600 J

Q = m Lf

600 = m (100)

m = 6 g will be melted.

solid sample = 20 - 6 = 14 g

Ans(B)

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P V / T =costant

P -> P/2

V-> 3 V

T -> 3/2 T

Ans(b)

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change in internal energy = 75 - 50 = 25 J

ans(d)

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