The heat capacity of solid alanine at 298 K is 125 J/mol. K. At zero Kelvin, the
ID: 475453 • Letter: T
Question
The heat capacity of solid alanine at 298 K is 125 J/mol. K. At zero Kelvin, the heat capacity is (always) zero. Assuming that the heat capacity of alanine powder is roughly linearly proportional to temperature, calculate the heat required to heat alanine from 200 K to 300 K. By finding the appropriate thermochemical values for C_8H_18, O_2, CO_2, and H_2O (ie, delta H_f^degree) in the textbook(Table 1.8 of page 60, delta H_f^degree=-5471 kJ/mol), calculate the energy released by the combustion of octane, C_8H_18, and the amount of octane (in grams) needed to expand a 2.5 L piston at 298 K and 1 atm. Ethanol is produced by oxidizing glucose: Calculate the heat energy released by this reaction at 25 degree C. The reaction often happens in a thermophilic bacterium at 80 degree C. Calculate the heat energy released if a single bacterium oxidizes 155 ng of glucose. The reaction can occur by itself in DI water (aqueous solution) or in a pH-buffered solution with a highly evolved enzyme. Would you expect delta H_RXN^degree to be different with or without the enzyme? Explain. The reaction can occur starting from solid glucose and forming liquid ethanol or it can start from aqueous glucose and form aqueous ethanol. Would you expect delta H_RXN^degree to be different for these two cases? Explain. The DNA segment AATGTCCT (segment 1) forms a double helix with the segment TTACAGGA (segment 2). 15 ml. of a 75 solution of segment 1 is mixed with 15 mL of a 75 mu M solution of segment 2. The temperature of the combined solution increases by 0.003 degree C (you are fortunate to have a very accurate calorimeter and precise thermometer). Assuming that 100 % of the DNA forms a double helix between the two segments, what is the average binding energy per base pair, in kJ/mol?Explanation / Answer
13)
heat capacity of alanine = 125 J/mol . K
temperature difference = 300 - 200 = 100 K
Heat required = n Cp dT
= 1 x 125 x 100
= 12500 J
heat required to heat aniline = 12500 J /mol
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