Hi, it would be great if I could have some help with the
following questions :)
1. Given
the reasoning that the standard enthalpy change of neutralisation
between weak acids/bases and strong acids/bases is lower as
compared to those between strong acids and bases because energy is
absorbed to ionize the undissociated weak acid/base, why is the
standard enthalpy change of the reaction:
CH3COOH + NH3 -> H2O +
CH3COONH4
greater than that of
neutralisation between weak acids/bases and strong acids/bases
since there should be more energy absorbed to ionize the greater
number of undissociated acid/base?
2. Since the units of enthalpy
change of reaction is kJ/mol, why does changing the stochiometry
coefficients still change the enthalpy change of a reaction? Should
this not be analogous to the concept of heat capacity and specific
heat capacity, where the value of the specific heat capacity is
constant for a particular material, regardless of mass, since the
units of specific heat capacity already “accounts” for the
mass?
Q1. There is a fundamental misconception with your question
(where did you even get this question? Did your JC ask you
that? Which JC do you come from?). Neutralization enthalpy is
defined as per mole of water generated. No water is generated in
the reaction between weak acids and weak bases.
Q2. kJ/mol is not per mole of any particular reactant or
product, but per mole of the equation.