In a constant-pressure calorimetry experiment, 31.0 mL of 1.00 M HClO4 was mixed
ID: 713236 • Letter: I
Question
In a constant-pressure calorimetry experiment, 31.0 mL of 1.00 M HClO4 was mixed with 31.0 mL of 1.00 M LiOH in a calorimeter. Both solutions were initially at 21.5 OC. The final temperature of the mixture was 29.0OC. The heat capacity of the calorimeter is 28.1J/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
total volume of solution = 3 + 31 = 62 mL
mass of solution = 62 x 1 = 62 g
temperature rise = 29 - 21.5 = 7.5 oC
Q = m Cp dT + Cp dT
= 62 x 4.184 x 7.5 + 28.1 x 7.5
Q = 2156.31 J
qreaction = 2.16 x 10^3 kJ