The following information is given for cadmium at 1atm: boiling point = 765.0oC
ID: 625008 • Letter: T
Question
The following information is given for cadmium at 1atm: boiling point = 765.0oC Hvap(765.0oC) = 889.6 J/g melting point = 321.0oC Hfus(321.0oC) = 54.40 J/g specific heat solid= 0.2300 J/goC specific heat liquid = 0.2640 J/goC A 32.70 g sample of liquid cadmium at 371.0 oC is poured into a mold and allowed to cool to 22.0 oC. How many kJ of energy are released in this process. Report the answer as a positive number.Explanation / Answer
follow this Since delta H = -726 KJ, the reaction is exothermic, so 726 kJ of energy is relesed. The energy itself is never negative, so it in this equation it must be placed on the right side of the equation. 2 CH3 OH (l) + 3 O2 (g) --> 2 CO2(g) + 4 H2O (l) + 726 kJ Next, use the dimensional analysis and the coefficients in the equation to first change 75.0 g of methanol to moles of methanol, then to kilojoules of energy. [(75.0 g CH3OH)/1][(1 mol CH3OH)/(36.074 CH3OH)][(726 kJ)/(2 mol CH3OH)] = 755 kJ Answer: 766 kilojoules of energy are released when 75.0 g of methanol is burned.
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