A Substance Has a Melting Point of 20°C and a Heat

question 34

Multiple Choice

A substance has a melting point of 20°C and a heat of fusion of 3.5 × 10⁴ J/kg.The boiling point is 150°C and the heat of vaporization is 7.0 × 10⁴ J/kg at a pressure of 1.0 atm.The specific heats for the solid,liquid,and gaseous phases are 600 J/(kg ∙ K) ,1000 J/(kg ∙ K) ,and 400 J/(kg ∙ K) ,respectively.The quantity of heat given up by 0.50 kg of the substance when it is cooled from 170°C to 88°C,at a pressure of 1.0 atmosphere,is closest to

• A)70 kJ.
• B)14 kJ.
• C)21 kJ.
• D)30 kJ.
• E)44 kJ.

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