Problem 48 - Chemistry: The Central Science

Question

Write the chemical formula for each of the following compounds, and indicate the oxidation state of the group \(6 \mathrm{~A}\) element in each: (a) sulfur tetrachloride, (b) selenium trioxide, (c) sodium thiosulfate, (d) hydrogen sulfide, (e) sulfuric acid.

Step-by-Step Solution

Answer

The chemical formulas and oxidation states of the group 6A elements in the given compounds are: (a) Sulfur tetrachloride: SCl_4, oxidation state of S: +4 (b) Selenium trioxide: SeO_3, oxidation state of Se: +6 (c) Sodium thiosulfate: Na_2S_2O_3, oxidation state of S: +2 (d) Hydrogen sulfide: H_2S, oxidation state of S: -2 (e) Sulfuric acid: H_2SO_4, oxidation state of S: +6

Step 1: Identify chemical symbols and numbers of atoms

Sulfur can be represented by the chemical symbol 'S' and chlorine by 'Cl'. There is one sulfur atom and four chlorine atoms.

Step 2: Write the chemical formula

The chemical formula of sulfur tetrachloride is: SCl_4

Step 3: Determine the oxidation state of sulfur

Since there are 4 chlorine atoms with an oxidation state of -1, the oxidation state of sulfur is: +4 (b) Selenium trioxide

Step 4: Identify chemical symbols and numbers of atoms

Selenium can be represented by the chemical symbol 'Se' and oxygen by 'O'. There is one selenium atom and three oxygen atoms.

Step 5: Write the chemical formula

The chemical formula of selenium trioxide is: SeO_3

Step 6: Determine the oxidation state of selenium

Since there are 3 oxygen atoms with an oxidation state of -2, the oxidation state of selenium is: +6 (c) Sodium thiosulfate

Step 7: Identify chemical symbols and numbers of atoms

Sodium can be represented by the chemical symbol 'Na', sulfur by 'S', and oxygen by 'O'. There are two sodium atoms, one sulfur atom, and three oxygen atoms.

Step 8: Write the chemical formula

The chemical formula of sodium thiosulfate is: Na_2S_2O_3

Step 9: Determine the oxidation state of sulfur

Since there are 2 sodium atoms with an oxidation state of +1 and 3 oxygen atoms with an oxidation state of -2, the total oxidation state of the two sulfur atoms is: +4. Since there are two sulfur atoms, the oxidation state of each sulfur atom is: +2 (d) Hydrogen sulfide

Step 10: Identify chemical symbols and numbers of atoms

Hydrogen can be represented by the chemical symbol 'H' and sulfur by 'S'. There are two hydrogen atoms and one sulfur atom.

Step 11: Write the chemical formula

The chemical formula of hydrogen sulfide is: H_2S

Step 12: Determine the oxidation state of sulfur

Since there are 2 hydrogen atoms with an oxidation state of +1, the oxidation state of sulfur is: -2 (e) Sulfuric acid

Step 13: Identify chemical symbols and numbers of atoms

Hydrogen can be represented by the chemical symbol 'H', sulfur by 'S', and oxygen by 'O'. There are two hydrogen atoms, one sulfur atom, and four oxygen atoms.

Step 14: Write the chemical formula

The chemical formula of sulfuric acid is: H_2SO_4

Step 15: Determine the oxidation state of sulfur

Since there are 2 hydrogen atoms with an oxidation state of +1 and 4 oxygen atoms with an oxidation state of -2, the oxidation state of sulfur is: +6

Key Concepts

Chemical Formula

Understanding the concept of a chemical formula is crucial for anyone studying chemistry. A chemical formula is a symbolic representation of the composition of a chemical compound. It shows the elements that are present in the compound and the relative number of atoms of each. For instance, when we look at sulfur tetrachloride, its chemical formula is written as SCl₄, indicating that one atom of sulfur (S) bonds with four atoms of chlorine (Cl).

Chemical formulas provide a wealth of information. They reveal the types of atoms involved, their proportions, and, in some instances, how the atoms are arranged in space. This is essential for predicting the behavior of compounds under different conditions, understanding their properties, and for the synthesis of new materials. When decoding a chemical formula, the subscript numbers indicate the quantity of each type of atom. No subscript implies there is only one atom of that element, as seen in selenium trioxide (SeO₃), where there is one selenium (Se) atom for every three oxygen (O) atoms.

Oxidation Numbers

Oxidation numbers, also known as oxidation states, play a pivotal role in understanding the electron transfer in chemical reactions, especially redox (reduction-oxidation) reactions. An oxidation number is a number assigned to an element in a compound that indicates the number of electrons it gains, loses, or shares when it forms chemical bonds.

In the chemical formula Na₂S₂O₃ (sodium thiosulfate), the oxidation state of sodium (Na) is +1, indicating that each sodium atom has

Inorganic Compounds

lost one electron. In the same formula, the two sulfur (S) atoms together have an oxidation state of +4, meaning they share two additional electrons between them. The concept of oxidation numbers also helps to balance chemical equations and to identify oxidizing and reducing agents in chemical reactions.

Oxidation numbers can be positive, negative, or zero, and they are determined based on a set of rules, considering the periodic table, electronegativity, and molecular structure. For instance, in sulfuric acid (H₂SO₄), the sulfur (S) atom has an oxidation number of +6 since the associated hydrogen atoms have an oxidation state of +1 and the oxygen atoms have an oxidation state of -2, leading to a balanced charge in the compound.