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(2) Compare the molar enthalpies of neutralization of hydrochloric acid, sulfuri

ID: 547296 • Letter: #

Question

(2) Compare the molar enthalpies of neutralization of hydrochloric acid, sulfuric acid, and phosphoric acid. Discuss the similarities and differences of these data. I ust d the stfuic od When a neutralization reaction was carried out using 100.0 mL of 0.7890M NHj water and 100.0 mL of 0.7940M acetic acid, AT was found to be 4.76 °C. The specific heat of the reaction mixture was 4.104 8 K-1 and its density was 1.03 g mL.-1. The calorimeter constant was 3.36 J K (1) Calculate Hneutzn for the reaction of NH3 and acetic acid. + 0oHNH4,100 729.ist loo+ loo) x 1.03 2069 answer (3.36x ·211 neriment, it was discovered that the thermometer had not been rad .50 C low.Whate

Explanation / Answer

3)

mass of solution = (100 + 100 ) x 1.03 = 206 g

temperature change = 4.70

specific heat = 4.104 J / g oC

Q = m Cp dT + Cp dT

   = 206 x 4.104 x 4.70 + 3.36 x 4.70

Q = 3989.3 J

moles of NH3 = 100 x 0.7890 / 1000 = 0.0789

moles of CH3COOH = 100 x 0.7940 / 1000 = 0.0794

here limting reagent is NH3.

delta H = - Q / n = - 3989.3 x 10^-3 / 0.0789

           = - 50.56 kJ /mol

heat of neutralization = - 50.56 kJ/mol

4)

if delta T = 4.76

Q = 4040.211 J

delta H = - 51.207 kJ/mol

% error = theoretical - actual / theoretical ) x 100

            = - 51.207 + 50.56 / 51.207 ) x 100

           = 1.26 %