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, \((\mathrm{e})\) sulfuric acid.

Short answer

The chemical formulas for the given compounds are as follows: (a) Sulfur tetrachloride: SCl4, (b) Selenium trioxide: SeO3, (c) Sodium thiosulfate: Na2S2O3, (d) Hydrogen sulfide: H2S, (e) Sulfuric acid: H2SO4. The oxidation states of the group 6A elements are: (a) Sulfur in Sulfur Tetrachloride: +4, (b) Selenium in Selenium Trioxide: +6, (c) Sum of oxidation states of Sulfur in Sodium Thiosulfate: +4, (d) Sulfur in Hydrogen Sulfide: -2, (e) Sulfur in Sulfuric Acid: +6.

Step-by-step solution

(a) Sulfur Tetrachloride

For sulfur tetrachloride, we have a sulfur atom (S) bonding with four chlorine atoms (Cl). So, the chemical formula will be SCl4.

(b) Selenium Trioxide

For selenium trioxide, we have a selenium atom (Se) bonding with three oxygen atoms (O). So, the chemical formula will be SeO3.

(c) Sodium Thiosulfate

For sodium thiosulfate, we have two sodium atoms (Na), one sulfur atom (S), and three oxygen atoms (O). So, the chemical formula will be Na2S2O3.

(d) Hydrogen Sulfide

For hydrogen sulfide, we have a sulfur atom (S) bonding with two hydrogen atoms (H). So, the chemical formula will be H2S.

(e) Sulfuric Acid

For sulfuric acid, we have a sulfur atom (S) bonding with four oxygen atoms (O) and two hydrogen atoms (H). So, the chemical formula will be H2SO4. Step 2: Determine the Oxidation State

(a) Oxidation State of Sulfur in Sulfur Tetrachloride

We let the oxidation state of Sulfur be x. Each chlorine atom (-1 charge) contributes a -1 charge. So, we have: x + 4(-1) = 0 x = +4

(b) Oxidation State of Selenium in Selenium Trioxide

We let the oxidation state of Selenium be x. Each oxygen atom (-2 charge) contributes a -2 charge. So, we have: x + 3(-2) = 0 x = +6

(c) Oxidation State of Sulfur in Sodium Thiosulfate

We have two sulfur atoms, one with an oxidation state of x and another with an oxidation state of y. Each sodium atom (+1 charge) contributes a +1 charge, and each oxygen atom (-2 charge) contributes a -2 charge. So, we have: 2(+1) + x + y + 3(-2) = 0 x + y = +4 Since we can't precisely determine the oxidation states of each sulfur atom in this compound, we can only say that the sum of their oxidation states is +4.

(d) Oxidation State of Sulfur in Hydrogen Sulfide

We let the oxidation state of Sulfur be x. Each hydrogen atom (+1 charge) contributes a +1 charge. So, we have: x + 2(+1) = 0 x = -2

(e) Oxidation State of Sulfur in Sulfuric Acid

We let the oxidation state of Sulfur be x. Each oxygen atom (-2 charge) contributes a -2 charge, and each hydrogen atom (+1 charge) contributes a +1 charge. So, we have: x + 4(-2) + 2(+1) = 0 x = +6 So, the oxidation states of the group 6A elements are as follows: (a) Sulfur in Sulfur Tetrachloride = +4 (b) Selenium in Selenium Trioxide = +6 (c) Sum of oxidation states of Sulfur in Sodium Thiosulfate = +4 (d) Sulfur in Hydrogen Sulfide = -2 (e) Sulfur in Sulfuric Acid = +6

Key concepts

Chemical Formulas

Chemical formulas provide a simple way to represent the composition of a compound. They use symbols for the elements combined with numerical subscripts to show the number of each type of atom in a molecule. For example, the chemical formula for water is H₂O, indicating two hydrogen atoms and one oxygen atom per molecule.

Writing a chemical formula involves knowing the elements involved and their proportions. For instance, sulfur tetrachloride has the formula SCl₄, meaning one sulfur atom is combined with four chlorine atoms. When writing down these formulas, it's crucial to balance the charges if it’s an ionic compound, to maintain a neutral charge.

Remember, while covalent compounds like sulfur tetrachloride use prefix names to denote the number of atoms, ionic compounds will depend on the charge of ions involved.

Sulfur Compounds

Sulfur compounds are crucial in chemistry and exhibit various oxidation states, which affect their chemical behavior. They include simple molecules like hydrogen sulfide (H₂S), where sulfur is combined with hydrogen. Here, sulfur exhibits an oxidation state of -2, as it gains electrons from the more electropositive hydrogen atoms.

Another important sulfur compound is sulfuric acid (H₂SO₄), a strong acid and oxidizer. It features sulfur in a +6 oxidation state, obtained after it shares electrons with more electronegative oxygen. Sulfur forms compounds like thiosulfates, Na₂S₂O₃, where sulfur itself appears in mixed oxidation states.

Understanding the oxidation state and bonding structure can help predict reactivity and properties of sulfur compounds, making them significant in industrial applications, such as in the production of fertilizers or as part of various chemical reactions.

Group 6A Elements

Group 6A elements, also known as the chalcogens, include oxygen, sulfur, selenium, tellurium, and polonium. These elements are characterized by their ability to form -2 oxidation states, similar to oxygen, but they also form various positive oxidation states.

Sulfur and selenium especially, share similar chemical properties. They can form multiple oxides and their ability to have various oxidation states (+2, +4, +6) makes them versatile.

These elements are non-metals, often participating in covalent bond formation with metals and non-metals alike. Their presence in many biological and industrial compounds, like amino acids or the conductive materials, highlights their importance.

Selenium Compounds

Selenium, a member of Group 6A, forms compounds where it can exhibit different oxidation states. One common selenium compound is selenium trioxide, SeO₃, with selenium in a +6 oxidation state.

This compound is formed by bonding selenium with three oxygen atoms. It is analogous to sulfur trioxide and exhibits similar reactions and uses. Selenium compounds are influential in electronics and glassmaking due to their ability to enhance conductivity or alter light properties.

While sharing similarities with sulfur, selenium compounds sometimes exhibit unique behaviors due to their slightly larger atomic size and different electronegativity. It's essential to understand these nuances to predict the behavior of selenium in various chemical reactions.

Sodium Thiosulfate

Sodium thiosulfate is a compound with the chemical formula Na₂S₂O₃. It's widely recognized for its application in the photographic industry for removing silver halides, and in medicine, as an antidote for cyanide poisoning.

In sodium thiosulfate, sulfur exhibits mixed oxidation states, often making it a versatile and useful compound in redox reactions. The complex structure allows it to participate effectively in a variety of chemical processes.

The 'thio-' prefix indicates the presence of sulfur replacing an oxygen atom in related compounds, here showing the unique chemistry that sulfur can impart to an otherwise typical sulfate structure. This chemical peculiarity offers diverse uses in both industrial and analytical chemistry.