Write the HA reaction for each acid below. Account for the following activity order by drawing the important resonance contributing structures (those having only one negative (-) formal charge) for A-.
HA + H2O <---> H3O+ + A-
stronger HClO4>HClO3>HClO weaker
H2SO4>H2SO3
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To write the HA reaction and account for the activity order, we need to consider the strength of the acids. The activity order you provided is:
stronger: HClO4 > HClO3 > HClO weaker
stronger: H2SO4 > H2SO3
Let's start by writing the HA reaction and determining the important resonance structures for A- in each case:
1. HClO4:
The reaction is: HClO4 + H2O ⇌ H3O+ + ClO4-
To determine the important resonance structures for ClO4-, we need to consider the Lewis structure of ClO4-. The central atom is Cl (chlorine), surrounded by four oxygen atoms (O). Start by drawing the Lewis structure of ClO4-, making sure all atoms have a full octet. Each oxygen atom will have a single bond with the chlorine atom, and three lone pairs of electrons. The chlorine atom will have a single bond with one oxygen atom, and a double bond with another oxygen atom (to complete its octet). The other two oxygen atoms will form double bonds with the chlorine atom.
2. HClO3:
The reaction is: HClO3 + H2O ⇌ H3O+ + ClO3-
To determine the important resonance structures for ClO3-, follow the same steps as above. Draw the Lewis structure for ClO3- with chlorine as the central atom and three oxygen atoms. Each oxygen atom forms a single bond with the chlorine atom and has two lone pairs of electrons. Two of the oxygen atoms will form a double bond with the chlorine atom, while the remaining oxygen atom will have a single bond.
3. HClO:
The reaction is: HClO + H2O ⇌ H3O+ + ClO-
To determine the important resonance structures for ClO-, again follow the same steps as above. The Lewis structure for ClO- will have chlorine as the central atom and only one oxygen atom. The oxygen atom forms a single bond with the chlorine atom and has two lone pairs of electrons.
4. H2SO4:
The reaction is: H2SO4 + H2O ⇌ H3O+ + HSO4-
To determine the important resonance structures for HSO4-, focus on the HSO4- ion. The hydrogen atom (H) is bonded to a central sulfur atom (S), which is surrounded by four oxygen atoms (O). Each oxygen atom will form a single bond with the sulfur atom and have two lone pairs of electrons. One of the oxygen atoms will form a double bond with the sulfur atom, completing its octet.
5. H2SO3:
The reaction is: H2SO3 + H2O ⇌ H3O+ + HSO3-
To determine the important resonance structures for HSO3-, follow the same steps as before. The HSO3- ion will have a central sulfur atom bonded to three oxygen atoms. Two of the oxygen atoms will form single bonds with the sulfur atom and have two lone pairs of electrons. One oxygen atom will form a double bond with the sulfur atom, completing its octet.
By drawing these important resonance structures, you can visualize the electron distribution and stability of the resulting anions (A-) for each acid.