Chemistry 112 Spring 2025
Chapter 14
PRE-CLASS ASSIGNMENT 14.4
In the first half of this Chapter (14.1-14.3), we discussed how to quantitatively describe aqueous
solutions of acids and bases via calculations of pH, pOH, Ka, and Kb. We also distinguished
between strong and weak acids/bases, and described how strong acids/bases dissociate fully in
solution whereas weak acids/bases dissociate incompletely. What’s been missing from our
discussion, thus far, is a molecular-level understanding of acids and bases. Why are some acids
strong while others are weak? Why does acetic acid (CH3COOH) react to form CH3COO– and not
CH2COOH–? When H2SO4 reacts does it lose one or both protons? Let’s find out!
Watch https://youtu.be/ytULYN-D3l4 . Define each of the following terms:
Binary acid: An acid composed of hydrogen and one other nonmetal element.
Oxoacid: An acid that contains hydrogen, oxygen, and another element (the central atom).
Polyprotic Acid: An acid that can donate more than one proton per molecule.
Explain how each of the following factors influences the strength of a binary acid:
Molecular size: The larger the size of the non-hydrogen atom (X), the weaker the bond to
hydrogen, making it easier to donate H+ and increasing acid strength.
Electronegativity of X (the non-H element): Higher electronegativity pulls electron density
away from the hydrogen, weakening the H-X bond and making the acid stronger.
Binary acid:
Oxoacid:
Polyprotic Acid:
Molecular size:
Electronegativity of X (the non-H element):
Stability of the conjugate base:
