Question

b. In a calorimetric exp periment, why is it important to determine the heat capacity of the -calorimeter? be able No losorbe a lot af h ea 2. Two solutions namely, 500 mL of 0.50 M HCl and 500 mL of 0.50 M NaOH at the same temperature of 2L6C are mixed in a constant-pressure calorimeter. The heat capacity of the calorimeter was450 J/oC. Given thatthe-specific heat of the solution is 4.184 J/g C, the density of the solution is 1.00 g/mL, and that the heat of neutralization for the process H-4aqtOH (aq)→ H2O (l) is-562 k, what is the final temperature of the mixed solution? 11-1 CHEM1314-YEAR-2018-2019

Answer 1

Q2. volume HCl = 500 mL = 0.500 L

moles HCl = (molarity HCl) * (volume HCl)

moles HCl = (0.5 M) * (0.500 L)

moles HCl = 0.25 mol

similarly, moles NaOH = 0.25 mol

moles water formed = moles HCl = moles NaOH = 0.25 mol

heat released = (heat of neutralization) * (moles water formed)

heat released = (-56.2 kJ/mol) * (0.25 mol)

heat released = -14.05 kJ

heat gained by solution and calorimeter = -heat released

heat gained by solution and calorimeter = -(-14.05 kJ)

heat gained by solution and calorimeter = 14.05 kJ

heat gained by solution and calorimeter = 14050 J

Also,

heat gained by solution and calorimeter = [(mass of solution) * (specific heat of solution) + heat capacity of calorimeter] * (final temperature - initial temperature)

heat gained by solution and calorimeter = [(m_sol) * (C_sol) + C_cal] * (T_f - T_i)

Total volume of solution = 500 mL + 500 mL = 1000 mL

mass of solution = (volume of solution) * (density of solution)

mass of solution = (1.00 g/mL) * (1000 mL)

mass of solution = 1000 g

Substituting the values,

14050 J = [(1000 g) * (4.184 J/g.^oC) + 450 J/^oC] * (T_f - 21.6 ^oC)

14050 J = (4184 J/^oC) + 450 J/^oC) * (T_f - 21.6 ^oC)

14050 J = (4634 J/^oC) * (T_f - 21.6 ^oC)

T_f - 21.6 ^oC = (14050 J) / (4634 J/^oC)

T_f - 21.6 ^oC = 3.0 ^oC

T_f = 3.0 ^oC + 21.6 ^oC

T_f = 24.6 ^oC

Final temperature of the mixed solution is 24.6 ^oC