In a constant-pressure calorimetry experiment, 26.0 mL of 1.00 M HClO4 was mixed
ID: 908565 • Letter: I
Question
In a constant-pressure calorimetry experiment, 26.0 mL of 1.00 M HClO4 was mixed with 26.0 mL of 1.00 M LiOH in a calorimeter. Both solutions were initially at 21.5 OC. The final temperature of the mixture was 31.0OC. The heat capacity of the calorimeter is 27.1J/OC. The specific heat of the reaction mixture is 4.184 J/g°C and the density of all solutions is 1.00 g/mL. Calculate the qreaction. Report the numerical answer in kJ with correct significant digits (without units and not in scientific notation).
Explanation / Answer
q(reaction) = q(sys) + q(cal)
Total mass of solution = (26 + 26)g x 1.0 g/ml = 52 g
q(reaction) = mCpdT = 52 x 4.184 x (31-21.5) = 2.07 kJ
q(cal) = CdT = 27.1 x (31-21.5) = 0.257 kJ
Total heat of reaction,
q(reaction) = 2.07 + 0.257 = 2.33 kJ