Final answer:
The assertion that temperature is the only factor that influences the acid dissociation constant (Ka) is false. Temperature is an important factor, but not the only one; ionic strength and common ions also play roles.
Step-by-step explanation:
The statement that temperature is the only external factor that will affect Ka is false. While temperature is indeed a significant factor affecting the Ka, which is the acid dissociation constant, other factors such as the ionic strength of the solution and the presence of common ions can also influence the Ka. The magnitude of the equilibrium constant (K) is directly related to the free energy change (∆G), and K changes as a function of temperature can be predicted by understanding the enthalpy (∆H) and entropy (∆S) changes associated with the reaction. For an exothermic reaction, an increase in temperature typically results in a decrease in the Ka, while for an endothermic reaction, an increase in temperature usually leads to an increase in the Ka.