Problem 33 - Chemistry: An Atoms-Focused Approach

Question

Give the formula and charge of the oxoanion in each of the following compounds: (a) sodium hypobromite; (b) potassium sulfate; (c) lithium iodate; (d) magnesium nitrite.

Step-by-Step Solution

Answer

Based on the discussed compounds, determine the formula and charge of the oxoanion in each. (a) Sodium hypobromite Formula: BrO- Charge: -1 (b) Potassium sulfate Formula: SO4^2- Charge: -2 (c) Lithium iodate Formula: IO3- Charge: -1 (d) Magnesium nitrite Formula: NO2- Charge: -1

Step 1: (a) Sodium hypobromite

First, we need to identify the cation and anion in the compound. Sodium hypobromite is an ionic compound composed of the sodium ion (Na+) and the hypobromite ion. "Hypo" and "ite" indicate that this is a certain type of bromine-based oxoanion. The formula for the hypobromite ion is BrO-, and since it's hypo (less oxygen), it has one less oxygen atom than the corresponding "ite" form (bromite, BrO2-). So, the formula and charge of the oxoanion in sodium hypobromite are BrO- and -1, respectively.

Step 2: (b) Potassium sulfate

In the ionic compound potassium sulfate, the cation is potassium (K+) and the anion is sulfate. The sulfate ion is a sulfate-based oxoanion with a formula of SO4^2-. Therefore, the formula and charge of the oxoanion in potassium sulfate are SO4^2- and -2, respectively.

Step 3: (c) Lithium iodate

Lithium iodate is made up of lithium ions (Li+) and iodate ions. The "ate" suffix shows us that it's an iodine-based oxoanion with the maximum number of oxygen atoms. The formula for the iodate ion is IO3-. So, the formula and charge of the oxoanion in lithium iodate are IO3- and -1, respectively.

Step 4: (d) Magnesium nitrite

Finally, in the compound magnesium nitrite, the cation is magnesium (Mg^2+) and the anion is nitrite. The nitrite ion is an oxoanion containing nitrogen and oxygen, with one less oxygen atom than its corresponding "ate" form (nitrate, NO3-). The formula for the nitrite ion is NO2-. Therefore, the formula and charge of the oxoanion in magnesium nitrite are NO2- and -1, respectively.

Key Concepts

Sodium Hypobromite

Sodium hypobromite is an interesting compound, primarily because of the hypobromite ion it contains. This ion is part of a group called oxoanions, which are negatively charged ions (anions) that include oxygen as a key component.
The formula for the hypobromite ion is BrO-. This is noteworthy due to the "hypo" prefix and "ite" suffix. These indicate that the ion has one less oxygen atom than the bromite ion, which is represented by BrO2-.
The presence of sodium, which forms a Na+ cation, balances the charge of the hypobromite ion, resulting in the neutral compound known as sodium hypobromite.

Potassium Sulfate

Potassium sulfate is best known for its sulfate ion, an oxoanion that carries a significant charge. The sulfate ion has a formula of SO4^{2-}. This indicates the presence of four oxygen atoms bonded to a single sulfur atom, forming a stable structure that is common in chemistry.
Potassium, represented as K+, combines two of its ions with the sulfate ion to create a balanced and neutral compound.

• The "ate" suffix indicates this oxoanion is fully oxygenated, which means it has a full complement of oxygen.
• Potassium sulfate is widely used in industry and agriculture, particularly for its potassium and sulfur content, both essential nutrients.

Lithium Iodate

When you encounter lithium iodate, you're dealing with an oxoanion known as iodate, often seen in chemistry due to its iodine content. The formula for the iodate ion is IO3-. The "ate" suffix suggests that the ion has all the oxygen atoms typically present in such a compound, distinguishing it from hypo- and per- variations.

• In lithium iodate, Li+ ions balance the negatively charged iodate ion by creating an electrically neutral compound.
• It's notable in various applications including as an oxidizing agent.

Understanding iodate ions is crucial, as they are prevalent in both organic and inorganic chemistry.

Magnesium Nitrite

Magnesium nitrite features the unique nitrite ion, an oxoanion that consists of nitrogen bonded with two oxygen atoms, forming NO2-. This ion is intriguing because it holds one less oxygen than the nitrate ion, NO3-.
For magnesium nitrite, the compound needs two nitrite ions to counterbalance the charge of one Mg^{2+} ion.

• Magnesium, with a 2+ charge, pairs with two negatively charged nitrite ions for electrical neutrality.
• The nitrite ion exhibits resonance, meaning the electrons are delocalized over the nitrogen and oxygen, providing extra stability.

This compound is interesting in studying the differences and similarities in oxoanions.