Question

Classify each of the following as a binary ionic compound, ternary ionic compound, binary molecular compound, binary acid, or ternary oxyacid: (a) water, \(\mathrm{H}_{2} \mathrm{O}\) (b) table salt, \(\mathrm{NaCl}\) (c) limestone, \(\mathrm{CaCO}_{3}\) (d) stomach acid, \(\mathrm{HCl}(a q)\)

Short answer

(a) Binary molecular compound (b) Binary ionic compound (c) Ternary ionic compound (d) Binary acid

Step-by-step solution

Classify water

Water, \( \mathrm{H}_{2} \mathrm{O} \), is a compound composed of two nonmetals: hydrogen (H) and oxygen (O). Therefore, it is classified as a **binary molecular compound**.

Classify table salt

Table salt, \( \mathrm{NaCl} \), consists of a metal (sodium, \( \mathrm{Na} \)) and a nonmetal (chlorine, \( \mathrm{Cl} \)). Consequently, it is classified as a **binary ionic compound**.

Classify limestone

Limestone, \( \mathrm{CaCO}_{3} \), contains calcium (Ca), a metal, and a polyatomic ion, carbonate \( (\mathrm{CO}_{3}^{2-}) \). As it contains a metal and polyatomic ion, it is classified as a **ternary ionic compound**.

Classify stomach acid

Stomach acid, \( \mathrm{HCl}(aq) \), is composed of hydrogen (H) and chlorine (Cl), both nonmetals, but it plays the role of an acid when aqueous. This makes it a **binary acid**.

Key concepts

Binary Ionic Compound

Binary ionic compounds are made up of two elements: a metal and a non-metal. When a metal atom transfers one or more of its electrons to a non-metal atom, an ionic bond is formed. This ionic bond holds the compound together. A familiar example is table salt, NaCl. Sodium (Na) is a metal, and chlorine (Cl) is a non-metal. When sodium gives up an electron to chlorine, a strong electrical attraction occurs, creating NaCl. This type of compound typically forms crystalline structures with high melting and boiling points. Examples of binary ionic compounds include:

• Sodium chloride ( b bnb{{NaCl}})
• Magnesium oxide ( b bnb{{MgO}})
• Calcium fluoride ( b bnb{{CaF}}_2)

Binary ionic compounds conduct electricity when dissolved in water, making them important in chemistry and industry.

Ternary Ionic Compound

Ternary ionic compounds contain three elements, typically involving a metal and a polyatomic ion. A polyatomic ion is a charged group of covalently bonded atoms that function as a single ion. In ternary ionic compounds, this combination extends the structure beyond the more straightforward binary ionic type. An example is limestone, or calcium carbonate ( b bnb{{CaCO}}_3). Here, calcium (Ca), a metal, combines with the polyatomic carbonate ion ( b bnb{{CO}}_3^{2-}). These compounds are characterized by their stability and varying solubility in water. Common examples include:

• Calcium carbonate ( b bnb{{CaCO}}_3)
• Sodium nitrate ( b bnb{{NaNO}}_3)
• Potassium sulfate ( b bnb{{K}}_2 b{{SO}}_4)

In essence, ternary ionic compounds expand the possibilities for ionic bonding in nature and industry.

Binary Molecular Compound

Binary molecular compounds are primarily formed between two non-metal elements. Unlike ionic compounds, which rely on electron transfer, molecular compounds share electrons. Water ( b bnb{{H}}_2 b bnb{{O}}) is a prime example as it consists of two hydrogen atoms bonded to one oxygen atom. The sharing of electrons creates a covalent bond, which holds the atoms together. Features of binary molecular compounds include:

• Exist as discrete molecules rather than network structures.
• Generally have lower melting and boiling points compared to ionic compounds.
• Often do not conduct electricity.

Other examples of binary molecular compounds:

• Carbon dioxide ( b bnb{{CO}}_2)
• Sulfur dioxide ( b bnb{{SO}}_2)
• Nitrogen dioxide ( b bnb{{NO}}_2)

These properties make binary molecular compounds crucial in everyday life, especially in biological and chemical processes.

Binary Acid

Binary acids consist of hydrogen and one other non-metal element. When dissolved in water, they act as acids. For example, stomach acid is hydrochloric acid ( b bnb{{HCl}}(aq)), which consists of hydrogen and chlorine. In an aqueous solution, the hydrogen ion ( b bnb{{H}}{^+}) is released, which is responsible for the compound's acidic nature. Binary acids are usually characterized by:

• The prefix "hydro-" and the suffix "-ic acid."
• Being strong acids with high dissociation in water, which makes them excellent conductors of electricity.

Common examples of binary acids are:

• Hydrochloric acid ( b bnb{{HCl}}(aq))
• Hydrobromic acid ( b bnb{{HBr}}(aq))
• Hydroiodic acid ( b bnb{{HI}}(aq))

These acids are vital in many chemical reactions, making them fundamental in both industrial applications and biological systems.