I am stuck with question 26 of Chapter 5 in Kotz\'s Chemistry and ChemicalReacti

Question

I am stuck with question 26 ofChapter 5 in Kotz's Chemistry and ChemicalReactivity (7th edition). I am unsure of where to evenbegin in this particular question. It states: "A 25.0mL sampleof benzene at 19.9°C was cooled to itsmelting point, 5.5°C, and then frozen. Howmuch energy as heat was given off in this process?" Density of benzene:0.80g/mL Specific heat capacity ofbenzene: 1.74J/g.K Heat of fusion of benzene:127J/g I am stuck with question 26 ofChapter 5 in Kotz's Chemistry and ChemicalReactivity (7th edition). I am unsure of where to evenbegin in this particular question. It states: "A 25.0mL sampleof benzene at 19.9°C was cooled to itsmelting point, 5.5°C, and then frozen. Howmuch energy as heat was given off in this process?" Density of benzene:0.80g/mL Specific heat capacity ofbenzene: 1.74J/g.K Heat of fusion of benzene:127J/g

Explanation / Answer

       q1 = m * s*T        mass of benzene = 25.0 mL * 0.8 g/mL                                    = 20g        specific heat =1.74 J /g.K             T = 5.5oC - 19.9oC               = -14.4 oC          q1 = 20 g *1.74 J/g.K * ( -14.4oC)               = -501.12 J      At 5.5 oC benzenefreezes .            q2 = - (20 g * 127 J/g)                = -2540 J             total heat enrgy given off in this process is Q = -501.12J + ( -2540 J)                                                                                       =   -3041.12 J

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