In: Chemistry
When 24.7 mL of 0.500 M H2SO4 is added to 24.7 mL of 1.00 M KOH in a coffee-cup calorimeter at 23.50°C, the temperature rises to 30.17°C. Calculate ΔH of this reaction. (Assume that the total volume is the sum of the individual volumes and that the density and specific heat capacity of the solution are the same as for pure water.) (d for water = 1.00 g/mL; c for water = 4.184 J/g·°C.)
.................. kJ/mol H2O
moles of acid H2SO4 = 24.7 x 0.50 / 1000 = 0.0124
moles of NaOH = 24.7 x 1.0 / 1000 = 0.0247
H2SO4 + 2 NaOH ------------------------> Na2SO4 + 2H2O
1 2
0.0124 0.0247
here both are consumed
moles of water fomred = 0.0247
total volume = 24.7 + 24.7 = 49.4 mL
mass of solution = volume x density
= 49.4 x 1
= 49.4 g
dT = 30.17 -23.50 = 6.67 oC
Q = 49.4 x 4.184 x 6.67
Q = 1379 J
molar enthalpy of neutralization = - Q / n
= -1.379 / 0.0247
= - 55.8 kJ / mol