Question

Select the more acidic member of each of the following pairs: (a) ${\mathrm{V}}_2{\mathrm{O}}_5$ and VO, (b) $\mathrm{PbO}$ and ${\mathrm{PbO}}_2$, (c) ${\mathrm{N}}_2{\mathrm{O}}_3$ and ${\mathrm{N}}_2{\mathrm{O}}_2,$ (d) ${\mathrm{SO}}_2$ and ${\mathrm{SeO}}_2,$ (e) ${\mathrm{Al}}_2{\mathrm{O}}_3$ and ${\mathrm{SeO}}_2,$ (f) ${\mathrm{CO}}_2$ and ${\mathrm{B}}_2{\mathrm{O}}_3$.

Short answer

The more acidic compound within each pair is: (a) V₂O₅ (b) PbO₂ (c) N₂O₃ (d) SO₂ (e) SeO₂ (f) CO₂

Step-by-step solution

Determine the oxidation states of the central atoms in each pair

For each of the compounds, we need to identify the oxidation state of the central atom. This will help us better understand each molecule and will enable us to compare them. (a) In V₂O₅, the oxidation state of V (vanadium) is +5, and in VO, the oxidation state of V is +2. (b) In PbO, the oxidation state of Pb (lead) is +2, and in PbO₂, the oxidation state of Pb is +4. (c) In N₂O₃, the oxidation state of N (nitrogen) is +3, and in N₂O₂, the oxidation state of N is +2. (d) In SO₂, the oxidation state of S (sulfur) is +4, and in SeO₂, the oxidation state of Se (selenium) is +4. (e) In Al₂O₃, the oxidation state of Al (aluminum) is +3, and in SeO₂, the oxidation state of Se (selenium) is +4. (f) In CO₂, the oxidation state of C (carbon) is +4, and in B₂O₃, the oxidation state of B (boron) is +3.

Compare the electronegativity and oxidation state of central atoms in each pair

Now, let's compare the electronegativity and oxidation state of the central atoms in each pair of compounds to gauge their acidity. (a) V₂O₅ has a higher oxidation state for V than VO, so V₂O₅ is more acidic. (b) PbO₂ has a higher oxidation state for Pb than PbO, so PbO₂ is more acidic. (c) N₂O₃ has a higher oxidation state for N than N₂O₂, so N₂O₃ is more acidic. (d) SO₂ and SeO₂ have the same oxidation state of +4. However, sulfur is more electronegative than selenium, so SO₂ is more acidic. (e) SeO₂ has a higher oxidation state for Se than Al₂O₃'s Al. Selenium is also less electronegative than aluminum, so SeO₂ is more acidic. (f) CO₂ has a higher oxidation state for C than B₂O₃'s B. Carbon is also more electronegative than boron, so CO₂ is more acidic.

Conclusion

The more acidic compound within each pair is as follows: (a) V₂O₅ (b) PbO₂ (c) N₂O₃ (d) SO₂ (e) SeO₂ (f) CO₂

Key concepts

Oxidation States

Understanding oxidation states is crucial when comparing the acidity of chemical compounds. The oxidation state indicates the degree of oxidation of an atom within a molecule. It is calculated by assuming that all bonds are ionic and assigning charges accordingly.

Here's how it works:

• Positive oxidation states mean the atom has lost electrons (oxidized).
• Higher oxidation states usually correspond to higher acidity in oxides.

Let's see how this applies:

• In ${\mathrm{V}}_2{\mathrm{O}}_5$, vanadium has a +5 oxidation state, making it more acidic compared to VO, where the oxidation state is +2.
• Similarly, in ${\mathrm{PbO}}_2$, lead has a +4 oxidation state compared to +2 in $\mathrm{PbO}$, indicating more acidity.

Electronegativity

Electronegativity helps us understand how atoms attract electrons during chemical bonding. It's a vital concept for determining acidity, particularly when oxidation states are equal.

Here are some key points:

• More electronegative elements attract electrons more strongly and can impact acidity.
• Among elements with the same oxidation state, the one that's more electronegative often forms a more acidic compound.

For example:

• ${\mathrm{SO}}_2$ and ${\mathrm{SeO}}_2$ both have central atoms with a +4 oxidation state. However, oxygen's greater electronegativity makes ${\mathrm{SO}}_2$ more acidic as sulfur attracts electrons more effectively than selenium.

Chemical Compounds

Chemical compounds are substances made up of atoms bonded together. The properties of these compounds can be influenced by the atoms' oxidation states and electronegativities.

Understanding the nature of chemical bonds can help us predict behavior such as acidity.

Consider these examples:

• ${\mathrm{N}}_2{\mathrm{O}}_3$ and ${\mathrm{N}}_2{\mathrm{O}}_2$ exhibit differences in acidity due to their differing oxidation states of nitrogen (+3 vs. +2).
• In ${\mathrm{CO}}_2$, carbon’s +4 oxidation state makes it more acidic in comparison to ${\mathrm{B}}_2{\mathrm{O}}_3$, where boron’s oxidation state is +3.

Acidity Comparison

Acidity comparison between compounds is essential to understand chemical reactions and properties. The acidity is often gauged by looking at the oxidation states and electronegativities.

Here's how comparisons are made:

• A higher oxidation state usually means stronger acidity due to increased charge separation.
• More electronegative atoms in the central position can create higher acidity levels.

When comparing ${\mathrm{Al}}_2{\mathrm{O}}_3$ and ${\mathrm{SeO}}_2$:

• ${\mathrm{SeO}}_2$ is more acidic as selenium has a higher oxidation state than aluminum and contributes to greater acidity.

By analyzing oxidation states and electronegativities, you can predict and compare the relative acidity of different oxides effectively.