Question

Determine the oxidation number of sulfur in each of the following substances: (a) barium sulfate, \(\mathrm{BaSO}_{4},\) (b) sulfurous acid, \(\mathrm{H}_{2} \mathrm{SO}_{3},\) (c) strontium sulfide, \(\mathrm{SrS},\) (d) hydrogen sulfide, \(\mathrm{H}_{2} \mathrm{~S} .\) (e) Based on these compounds what is the range of oxidation numbers seen for sulfur? Is there any relationship between the range of accessible oxidation states and sulfur's position on the periodic table?

Short answer

The oxidation numbers of sulfur in the given compounds are: (a) in barium sulfate (BaSO4), +6; (b) in sulfurous acid (H2SO3), +4; (c) in strontium sulfide (SrS), -2; and (d) in hydrogen sulfide (H2S), -2. The range of oxidation numbers for sulfur is from -2 to +6. This range is related to sulfur's position in group 16 on the periodic table, as it can gain, lose, or share electrons with other elements during chemical reactions due to the presence of lone pair electrons.

Step-by-step solution

Assign Oxidation Numbers to Barium Sulfate (BaSO4)

To assign oxidation numbers to the elements in barium sulfate, let's look at the author's list and their typical oxidation numbers. Barium (Ba) belongs to group 2 and generally forms +2 ions. Oxygen (O) typically has an oxidation number of -2. We can now write an equation and find the oxidation number of sulfur (S), represented by x: \(Ba^{+2} + S^{x} + 4O^{-2} = 0\) \(2 + x - 8 = 0\)

Calculate the Oxidation Number of Sulfur in BaSO4

Solving for x in the equation for the oxidation number of sulfur in BaSO4 gives us: \(x = 8 - 2\) \(x = +6\) Therefore, the oxidation number of sulfur in barium sulfate (BaSO4) is +6.

Assign Oxidation Numbers to Sulfurous Acid (H2SO3)

In sulfurous acid, hydrogen (H) has an oxidation number of +1 and oxygen (O) has an oxidation number of -2. We can now write an equation to find the oxidation number of sulfur (S), represented by x: \(2H^{+1} + S^{x} + 3O^{-2} = 0\) \(2 + x - 6 = 0\)

Calculate the Oxidation Number of Sulfur in H2SO3

Solving for x in the equation for the oxidation number of sulfur in H2SO3 gives us: \(x = 6 - 2\) \(x = +4\) Therefore, the oxidation number of sulfur in sulfurous acid (H2SO3) is +4.

Assign Oxidation Numbers to Strontium Sulfide (SrS)

Strontium (Sr) belongs to group 2 and generally forms +2 ions. We can now write an equation to find the oxidation number of sulfur (S), represented by x: \(Sr^{+2} + S^{x} = 0\) \(2 + x = 0\)

Calculate the Oxidation Number of Sulfur in SrS

Solving for x in the equation for the oxidation number of sulfur in SrS gives us: \(x = -2\) Therefore, the oxidation number of sulfur in strontium sulfide (SrS) is -2.

Assign Oxidation Numbers to Hydrogen Sulfide (H2S)

In hydrogen sulfide, hydrogen (H) has an oxidation number of +1. We can now write an equation to find the oxidation number of sulfur (S), represented by x: \(2H^{+1} + S^{x} = 0\) \(2 + x = 0\)

Calculate the Oxidation Number of Sulfur in H2S

Solving for x in the equation for the oxidation number of sulfur in H2S gives us: \(x = -2\) Therefore, the oxidation number of sulfur in hydrogen sulfide (H2S) is -2.

Determine the Range of Oxidation Numbers for Sulfur and its Relationship with the Periodic Table

Based on the compounds given, the oxidation numbers of sulfur are -2, +4, and +6. The range of oxidation numbers for sulfur is from -2 to +6. Sulfur belongs to group 16, also known as the oxygen family, and typically displays multiple oxidation states because of the presence of lone pair electrons. The range of accessible oxidation states for sulfur is directly related to its position on the periodic table and its ability to gain, lose, or share electrons with other elements during chemical reactions.

Key concepts

barium sulfate

Barium sulfate (BaSO₄) is a compound consisting of barium, sulfur, and oxygen. It is often used in medical imaging and as a pigment. Barium is from group 2 on the periodic table, meaning it usually carries a +2 oxidation number. Oxygen, which is a group 16 element like sulfur, also has a consistent oxidation number, which is -2. With these oxidation numbers, we determine sulfur's oxidation state in BaSO₄ by using the charge balance in the compound.

Here's how: Barium contributes a +2, and each of the four oxygen atoms contributes -2 each, totaling -8. To make the compound neutral, the oxidation state of sulfur must balance these values, giving sulfur an oxidation number of +6 in BaSO₄. It's like solving a simple math puzzle, where the total charges must equal zero for the compound to be stable.

sulfurous acid

Sulfurous acid, denoted as H₂SO₃, is an acid formed by dissolving sulfur dioxide in water. In this molecule, hydrogen typically has a +1 oxidation number, and oxygen carries a -2. Using these known values, we look for sulfur's oxidation number to ensure the molecule's neutrality.

Here’s the breakdown: We have two hydrogen atoms contributing a +2 charge, and three oxygen atoms contributing a -6 charge. For the charges to balance, sulfur’s oxidation number must be +4. This sees sulfur in a less oxidized state compared to barium sulfate, due to the fewer number of oxygen atoms bonded. Understanding this concept helps students get a handle on how acids differ from salts in terms of oxidation states.

strontium sulfide

Strontium sulfide (SrS) contains strontium and sulfur. Strontium is another group 2 element, similar to barium. Hence, it carries a typical +2 oxidation number. Sulfur's task here is to balance the charge from the strontium ion.

In strontium sulfide, you can think of the puzzle as determining what number, when added to +2, results in zero, since the compound needs to be neutral. Solving this little equation, we find sulfur has an oxidation number of -2. This is a reduced oxidation state, common when sulfur forms ions with metals, because sulfur has a natural tendency to accept electrons.

hydrogen sulfide

Hydrogen sulfide (H₂S) is a compound with a distinct rotten egg smell. It's simple yet crucial in understanding redox chemistry. With two hydrogen atoms, each having a +1 oxidation state, we determine sulfur’s oxidation number by balancing the charge to zero.

Using the same logic, since the total charge contribution from hydrogen is +2, sulfur must counterbalance it with a -2 charge. This means sulfur’s oxidation number here is -2. The simplicity of hydrogen sulfide makes it a go-to example for illustrating oxidation numbers and elemental tendencies in chemical reactions.