Question

Write the formula for each of the following compounds, and indicate the oxidation state of the halogen: (a) Paraperiodic acid (b) Chlorous acid

Short answer

Paraperiodic acid: \(H_5IO_6\), Iodine is +7; Chlorous acid: \(HClO_2\), Chlorine is +3.

Step-by-step solution

Identify the Halogen and Its Compound

Paraperiodic acid is known to contain iodine as the halogen, while chlorous acid contains chlorine. Identifying the halogen in each compound is crucial to determining the oxidation state.

Write the Chemical Formula

The chemical formula for paraperiodic acid is \( H_5IO_6 \) and for chlorous acid is \( HClO_2 \). These formulas represent the combination of hydrogen, oxygen, and the halogen in each acid.

Determine the Oxidation States

For paraperiodic acid \( H_5IO_6 \), we set up the equation: \( 5(+1) + x + 6(-2) = 0 \) to solve for the oxidation state of iodine. Simplifying gives \( 5 + x - 12 = 0 \), which means \( x = +7 \). For chlorous acid \( HClO_2 \), the equation is \( +1 + x + 2(-2) = 0 \). Simplifying gives \( 1 + x - 4 = 0 \), yielding \( x = +3 \). Thus, the oxidation state for iodine in paraperiodic acid is +7, and for chlorine in chlorous acid, it is +3.

Key concepts

Halogens

Halogens are a group of elements in the periodic table known for their high reactivity due to seven electrons in their outer shell. This group consists of five elements: fluorine, chlorine, bromine, iodine, and astatine. These elements typically gain an electron in reactions to form a stable compound, making them highly effective oxidizers.

• The word "halogen" comes from Greek roots meaning "salt-former," as these elements readily form salts when combined with metals.
• In the context of acids, halogens often combine with hydrogen and oxygen to form oxyacids, such as iodic and chlorous acids, in which their oxidation states can vary.

Understanding the behavior of halogens in such compounds is crucial for grasping the concept of oxidation states, helping us determine how they interact with other elements in chemical formulas.

Chemical Formula

A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. It indicates the types and ratios of atoms present. For example, in the compound paraperiodic acid, represented by the formula \(H_5IO_6\), the formula shows that it contains five hydrogen atoms, one iodine atom, and six oxygen atoms.

• In the formula \(H_5IO_6\), the subscript numbers tell you the number of each type of atom present in a single molecule of the compound.
• Similarly, for chlorous acid \(HClO_2\), the formula indicates one hydrogen, one chlorine, and two oxygen atoms.

These chemical formulas are fundamental in understanding the composition of compounds, guiding us in tasks such as identifying oxidation states or predicting reactions.

Iodine

Iodine is a halogen positioned prominently in Group 17 of the periodic table, known for its distinct violet color in the gaseous state. It is less reactive compared to other halogens like fluorine and chlorine. Iodine's role in forming acids like paraperiodic acid is significant in chemical reactions,where it assumes different oxidation states.

• In paraperiodic acid \(H_5IO_6\), iodine has an oxidation state of +7, which is its highest possible state, indicating a strong oxidation potential.
• This high oxidation state is balanced by the five hydrogen atoms each with +1 oxidation and six oxygen atoms each with -2, maintaining overall neutrality.

Understanding iodine's behavior in compounds illuminates how oxidation states are allocated and helps predict chemical behavior.

Chlorine

Chlorine is another vital element from the halogen family, well-known for its use in disinfectants and pool maintenance. It is highly reactive and plays a critical role in forming various acids, including chlorous acid. Unlike iodine, which has a broader range of positive oxidation states, chlorine predominantly achieves a modest range of oxidation states, crucial for different reactions.

• In the case of chlorous acid \(HClO_2\), chlorine has an oxidation state of +3.
• This oxidation state arises from combining one hydrogen atom with +1 and two oxygen atoms with -2, maintaining ionic equilibrium.

Chlorine’s reactivity and diverse oxidation states enable it to participate in various chemical reactions, significantly impacting everything from industrial processes to biological systems.