Question

NAME INSTRUCTOR DATE SECTION GROUP POST-LABORATORY QUESTIONS THERMOCHEMISTRY: ACID-BASE NEUTRALIZATION 1. Use Hess's Law and the class enthalpy values for the reactions of NaOH-HC and NH, HCl to calculate the enthalpy of neutralization of ammonium chloride and hydrochloric acid. You may need to reverse or multiply the chemical equations from Table 7.2 and 7.3 to get them to add up correctly: Experiment Chemical reaction (Refer to the reactions that you wrote in prelab question 3). Class enthalpy value (kJ/mol 7.2 NaOH-HCI | AH-6.234116 KJ NaOH + HCL H₂O + Nocl 73, NH, OH-Ha NaOH +HC\>HO + NH4Cl | AH-50%) AH calculated 74: NHỰCI-NaOH | NH4Cl +No OWN ROHC by Hess Law 2. Compare the enthalpy of neutralization of NH Cl(aq) that you calculated using the class values for enthalpies of neutralization in question 1, with your experimental value. Explain any differences between the values. 76 Thermochemistry: Acid-Base Neutralization

Answer 1

QUESTION 1.

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) , enthalpy= 6.23416 kJ -----------------------------EQUATION 1

HCl (aq) + NH4OH (l) → NH4Cl (aq) + H2O (l) , enthalpy= 5.6 kJ   -----------------------------EQUATION 2

EQUATION 1 - EQUATION 2 gives :

NH4OH (l) + NaCl (aq) → NH4Cl (aq) + NaOH (aq) ,  -----------------------------EQUATION 3

FOR WHICH ENTHALPY = Enthalpy of equation 1 -  Enthalpy of equation 2

= 0.63416 kJ.

QUESTION 2.

COMPARE THE ABOVE OBTAINED VALUE WITH YOUR EXPERIMENTAL VALUE.

Any changes or differences could be due to change in experimental conditions.