Problem 41 - Chemistry: The Central Science in SI Units, Global Edition

Question

Write the chemical formula for each of the following compounds, and indicate the oxidation state of the group 16 elements in each: (a) potassium peroxide, (b) potassium thiosulfate, \((\mathbf{c})\) selenium oxychloride, \((\mathbf{d})\) sodium telluride, (e) magnesium sulfite, (f) selenium hexafluoride.

Step-by-Step Solution

Answer

(a) Potassium Peroxide: K2O2 \((Oxidation State: O = -1)\) (b) Potassium Thiosulfate: K2S2O3 \((Oxidation State: S = +2, O = -2)\) (c) Selenium Oxychloride: SeOCl2 \((Oxidation State: Se = +4)\) (d) Sodium Telluride: Na2Te \((Oxidation State: Te = -2)\) (e) Magnesium Sulfite: MgSO3 \((Oxidation State: S = +4)\) (f) Selenium Hexafluoride: SeF6 \((Oxidation State: Se = +6)\)

Step 1: (a) Potassium Peroxide

Potassium Peroxide is formed by the reaction of potassium and oxygen under specific conditions. The chemical formula for potassium peroxide is K2O2. The group 16 element in this compound is oxygen. Since there are two potassium ions carrying a +1 charge each, the peroxide ion (O2^2-) carries a total of -2 charge. Each oxygen atom in the peroxide ion has an oxidation state of -1.

Step 2: (b) Potassium Thiosulfate

Potassium thiosulfate consists of potassium, sulfur, and oxygen. The chemical formula for potassium thiosulfate is K2S2O3. The group 16 element in this compound is oxygen and sulfur. In order to determine the oxidation state of sulfur, we use the algebraic sum method. Let x be the oxidation state of sulfur, then: 2(+1) + 2x + 3(-2) = 0 Solving this, we get the oxidation state of sulfur is +2. The oxidation state of oxygen remains -2.

Step 3: (c) Selenium Oxychloride

Selenium oxychloride is a compound consisting of selenium, oxygen, and chlorine. The chemical formula for selenium oxychloride is SeOCl2. Here, selenium is the group 16 element. To find the oxidation state of selenium, let x be its oxidation state: x + (-2) + 2(-1) = 0 Solving this, we get the oxidation state of selenium is +4.

Step 4: (d) Sodium Telluride

Sodium telluride is a compound formed from sodium and tellurium. The chemical formula for sodium telluride is Na2Te. The group 16 element in this compound is tellurium. Since there are two sodium ions carrying a +1 charge each, tellurium must carry a -2 charge to balance the charges. Thus, the oxidation state of tellurium is -2.

Step 5: (e) Magnesium Sulfite

Magnesium sulfite is a compound composed of magnesium, sulfur, and oxygen. The chemical formula for magnesium sulfite is MgSO3. The group 16 elements in this compound are sulfur and oxygen. The oxidation state of magnesium is +2 and that of oxygen is -2. Let x be the oxidation state of sulfur, then: (+2) + x + 3(-2) = 0 Solving this, we get the oxidation state of sulfur is +4.

Step 6: (f) Selenium Hexafluoride

Selenium hexafluoride is a compound containing selenium and fluorine. The chemical formula for selenium hexafluoride is SeF6. The group 16 element in this compound is selenium. The oxidation state of fluorine is always -1. Let x be the oxidation state of selenium: x + 6(-1) = 0 Solving this, we get the oxidation state of selenium to be +6.

Key Concepts

Chemical Formulas

Chemical formulas are a shorthand representation of the elements and the number of atoms present in a compound. They help in understanding the composition and structure of the compound by using the element symbols from the periodic table.
For example, potassium peroxide is represented as \( K_2O_2 \), indicating that it contains two potassium atoms and two oxygen atoms.
It's important to know the charges of individual ions to accurately determine the chemical formula. Each ion has a specific charge, which helps balance the formula so the compound is neutral overall. When writing these formulas, the sum of the positive and negative charges should always be zero.

• The subscript in the formula indicates the number of each type of atom in the compound.
• Coefficients are used to balance the overall formula charge.

Understanding chemical formulas is crucial for predicting the behavior and reactions of compounds in studies of chemistry.

Group 16 Elements

Group 16 elements, also known as the chalcogens, include oxygen, sulfur, selenium, tellurium, and polonium. These elements are critical in forming various inorganic compounds due to their unique properties.
Oxidation states are significant in determining how these elements interact with other elements. For instance, oxygen typically exhibits an oxidation state of -2, but in peroxides, it can have an oxidation state of -1, as seen in potassium peroxide (\( K_2O_2 \)).
Sulfur often displays multiple oxidation states, such as -2, +2, +4, and +6, which allows it to form diverse compounds like potassium thiosulfate (\( K_2S_2O_3 \)) and magnesium sulfite (\( MgSO_3 \)).

• Selenium and tellurium behave similarly to sulfur, having multiple oxidation states like +4 and +6.
• These variations in oxidation states allow group 16 elements to participate in a wide range of chemical reactions.

The versatility of group 16 elements is why they are vital in both biological and chemical processes.

Inorganic Compounds

Inorganic compounds are compounds which typically do not contain carbon-hydrogen bonds. These compounds are widely found in nature and play a key role in many chemical and physical processes.
An example includes sodium telluride (\( Na_2Te \)), comprised of sodium and tellurium, where tellurium exhibits an oxidation state of -2.
Inorganic compounds like selenium hexafluoride (\( SeF_6 \)) and selenium oxychloride (\( SeOCl_2 \)) highlight the diversity of chemical bonding among nonmetals.

• Often, these compounds have high melting and boiling points.
• They are generally good conductors of electricity in solution.

In the study of chemistry, understanding the structure, formation, and properties of inorganic compounds helps elucidate their applications in industrial processes and the environment.