my ap chem teacher has been absent for the past two weeks and part of the notes her sub gave us to copy says that
In the equation
HC2H3O2 + H20 <--> C2H3O2(- charge) + H3O(+ charge)
HC2H3O2 is an acid
H2O is a base
C2H3O2(- charge) is the conjugate base
and
H3O(+ charge) is the conjugate acid
but how would i know what each of those were?
or.. hm i don't know how to phrase this...
why is this so??
why is HC2H3O2 an acid?
what makes HC2H3O2 an acid?
and why is H2O a base?
what makes this a base?
According to the Bronsted-Lowry acid/base theory, an acid is a proton donor. A base is a proton acceptor. I'm going to write acetic acid like this CH3COOH (that's the same HC2H3O2 you have). The H on the right side is the acidic H; the others are not.
So in
CH3COOH + H2O ==> CH3COO^- + H3O^+
You see the CH3COOH has donated a proton to H2O. So CH3COOH is the acid, CH3COO^- is the conjugate base. The H2O molecule accepted the proton; therefore, it is a base and it formed the H3O^+ which is the conjugate acid.
What can act as both an acid and a base. In the above example it is a base. In the following example it is an acid.
NH3 + HOH ==> NH4^+ + OH^-
The NH3 is a base because it accepta a proton. That makes NH4^+ the conjugate acid. HOH donates a proton to the NH3; therefore, H2O is an acid. The OH^- is the conjugate base.
To understand why HC2H3O2 is an acid and H2O is a base in the given equation, we need to look at their characteristics and behavior in the context of acids and bases.
First, let's start with HC2H3O2 (acetic acid). Acids are substances that donate protons (H+) in a chemical reaction. In the equation shown, the HC2H3O2 molecule donates a proton (H+) to the water molecule, resulting in the formation of the hydronium ion (H3O+) and the conjugate base C2H3O2-. This donation of a proton is what classifies HC2H3O2 as an acid.
The reaction can be written as follows:
HC2H3O2 + H2O → C2H3O2- + H3O+
Now let's talk about H2O (water). Water can act as both an acid and a base, depending on the reaction it is involved in. In this particular equation, water accepts the proton (H+) donated by HC2H3O2, making it a base. Accepting a proton allows water to form the hydronium ion (H3O+), which is the conjugate acid in this reaction.
So, in summary:
- HC2H3O2 is an acid because it donates a proton (H+).
- H2O is a base because it accepts a proton (H+).
It is important to note that the classification of a substance as an acid or a base depends on how it behaves in a particular reaction and its ability to donate or accept protons. In other reactions, the same substances may exhibit different acid-base properties.