Question

Because many ions and compounds have very similar names, there is great potential for confusing them. Write the correct chemical formulas to distinguish between (a) sodium carbonate and sodium bicarbonate, (b) potassium peroxide and potassium oxide, \((\mathbf{c})\) calcium sulfide and calcium sulfate, \((\mathbf{d})\) manganese (II) oxide and manganese (III) oxide, (e) hydride ion and hydroxide ion, \((\mathbf{f})\) magnesium nitride and magnesium nitrite, \((\mathbf{g})\) silver nitrate and silver nitrite, \((\mathbf{h})\) cuprous oxide and cupric oxide.

Short answer

(a) Sodium carbonate: Na2CO3; sodium bicarbonate: NaHCO3. (b) Potassium peroxide: K2O2; potassium oxide: K2O. (c) Calcium sulfide: CaS; calcium sulfate: CaSO4. (d) Manganese (II) oxide: MnO; manganese (III) oxide: Mn2O3. (e) Hydride ion: H-; hydroxide ion: OH-. (f) Magnesium nitride: Mg3N2; magnesium nitrite: Mg(NO2)2. (g) Silver nitrate: AgNO3; silver nitrite: AgNO2. (h) Cuprous oxide: Cu2O; cupric oxide: CuO.

Step-by-step solution

(a) Sodium carbonate and sodium bicarbonate

Sodium carbonate has a formula Na2CO3 where the sodium ion has a charge of +1 and the carbonate ion has a charge of -2. Sodium bicarbonate has a formula NaHCO3, where the bicarbonate ion has a charge of -1.

(b) Potassium peroxide and potassium oxide

Potassium peroxide has a formula K2O2 where the potassium ion has a charge of +1 and the peroxide ion has a charge of -2. Potassium oxide has a formula K2O where the oxide ion has a charge of -2.

(c) Calcium sulfide and calcium sulfate

Calcium sulfide has a formula CaS where the calcium ion has a charge of +2 and the sulfide ion has a charge of -2. Calcium sulfate has a formula CaSO4 where the sulfate ion has a charge of -2.

(d) Manganese (II) oxide and manganese (III) oxide

Manganese (II) oxide has a formula MnO where manganese has a charge of +2 and the oxide ion has a charge of -2. Manganese (III) oxide has a formula Mn2O3 where manganese has a charge of +3 and oxide ion has a charge of -2.

(e) Hydride ion and hydroxide ion

The hydride ion has a formula H- which has a single negative charge. The hydroxide ion has a formula OH- which also has a single negative charge, but includes an oxygen atom bonded to the hydrogen atom.

(f) Magnesium nitride and magnesium nitrite

Magnesium nitride has a formula Mg3N2 where the magnesium ion has a charge of +2 and the nitride ion has a charge of -3. Magnesium nitrite has a formula Mg(NO2)2 where the nitrite ion has a charge of -1.

(g) Silver nitrate and silver nitrite

Silver nitrate has a formula AgNO3 where the silver ion has a charge of +1 and the nitrate ion has a charge of -1. Silver nitrite has a formula AgNO2 where the nitrite ion has a charge of -1.

(h) Cuprous oxide and cupric oxide

Cuprous oxide has a formula Cu2O where the copper (I) ion, also known as cuprous ion, has a charge of +1 and the oxide ion has a charge of -2. Cupric oxide has a formula CuO where the copper (II) ion, also known as cupric ion, has a charge of +2 and the oxide ion has a charge of -2.

Key concepts

Ions

Ions are atoms or molecules that have lost or gained one or more electrons, giving them a net charge. Ions play a crucial role in the formation of chemical compounds and are responsible for many of the properties of materials.

• Cations are positively charged ions, meaning they have more protons than electrons. For example, sodium (Na⁺) and calcium (Ca²⁺) are examples of cations.
• Anions are negatively charged ions, with more electrons than protons. Chloride (Cl^-) and sulfide (S^2-) are common anions.

When ions are involved in forming compounds, the opposite charges attract, helping to stabilize the compound. Recognizing the charge on an ion is essential, as it dictates how ions will combine to form stable chemical formulas. For instance, in sodium carbonate (Na₂CO₃), the sodium ion has a +1 charge and the carbonate ion a -2 charge, maintaining charge balance.

Chemical Nomenclature

Chemical nomenclature is the systematic naming of chemical compounds based on their composition and structure. This system helps chemists and students communicate unambiguously about chemical substances.

• The name often reveals crucial details about the compound's composition. For example, sodium bicarbonate signifies the presence of sodium (Na⁺) ion and bicarbonate (HCO₃^-) ion.
• Common suffixes like '-ate', '-ite', and '-ide' in the names of compounds indicate different ratios and types of elements. For instance, the difference between nitrates (NO₃^-) and nitrites (NO₂^-) is crucial, as reflected by their names and formulas.

Understanding chemical nomenclature can prevent confusion, especially with similar sounding compounds, such as sulfur dioxide (SO₂) and sulfur trioxide (SO₃). This knowledge is indispensable for deciphering chemical equations and understanding chemical reactions.

Oxidation States

Oxidation states, also known as oxidation numbers, represent the degree of oxidation of an atom in a chemical compound. This concept is central for understanding redox (reduction-oxidation) reactions.

• An element’s oxidation state helps identify how electrons are distributed within a compound. In manganese (II) oxide (MnO), manganese has an oxidation state of +2, indicating it has lost two electrons.
• Redox reactions often involve elements changing oxidation states, signifying electron transfer. For instance, moving from cuprous oxide (Cu₂O) with copper at +1 to cupric oxide (CuO) with copper at +2 represents an oxidation process.

Consistently identifying oxidation states allows chemists to predict the reactivity of substances, how they interact during chemical reactions, and in balancing chemical equations. By mastering the concept of oxidation states, you gain deeper insights into the energy changes and electron flow in reactions.