Problem 112 - Chemistry: The Central Science in SI Units, Global Edition

Question

Many familiar substances have common, unsystematic names. For each of the following, give the correct systematic name: \((\mathbf{a})\) saltpeter, \(\mathrm{KNO}_{3} ;(\mathbf{b})\) soda ash, \(\mathrm{Na}_{2} \mathrm{CO}_{3} ;(\mathbf{c})\) lime, \(\mathrm{CaO} ;\) (d) muriatic acid, HCl; (e) Epsom salts, \(\mathrm{MgSO}_{4} ;\) (f) milk of magnesia, \(\mathrm{Mg}(\mathrm{OH})_{2}\).

Step-by-Step Solution

Answer

The correct systematic names for the substances are: 1. Saltpeter - Potassium nitrate 2. Soda ash - Sodium carbonate 3. Lime - Calcium oxide 4. Muriatic acid - Hydrochloric acid 5. Epsom salts - Magnesium sulfate 6. Milk of magnesia - Magnesium hydroxide

Step 1: Saltpeter (KNO3)

The systematic name for KNO3, containing potassium (K), nitrogen (N), and oxygen (O) is "Potassium nitrate".

Step 2: Soda ash (Na2CO3)

The systematic name for Na2CO3, containing sodium (Na) and carbonate ion (CO3), is "Sodium carbonate".

Step 3: Lime (CaO)

The systematic name for CaO, containing calcium (Ca) and oxygen (O), is "Calcium oxide".

Step 4: Muriatic acid (HCl)

The systematic name for HCl, containing hydrogen (H) and chlorine (Cl), is "Hydrochloric acid".

Step 5: Epsom salts (MgSO4)

The systematic name for MgSO4, containing magnesium (Mg) and sulfate ion (SO4), is "Magnesium sulfate".

Step 6: Milk of magnesia (Mg(OH)2)

The systematic name for Mg(OH)2, containing magnesium (Mg) and hydroxide ion (OH), is "Magnesium hydroxide".

Key Concepts

Common vs. Systematic Names

Chemical compounds often have both common and systematic names, which can be confusing for beginners. Common names are traditional names that many people recognize, but they don't always tell you about the composition or the structure of the compound. For example:

• "Saltpeter" is known systematically as Potassium nitrate ( KNO_3 ).
• "Muriatic acid" is typically referred to as Hydrochloric acid ( HCl ) in systematic terms.

Systematic names follow a set of rules devised by the International Union of Pure and Applied Chemistry (IUPAC), and they help us understand the component elements or ions and their proportions.
This makes them particularly useful for scientists and students who need to understand the precise nature of the compound. While it may be easier to remember common names, learning systematic names provides a standardized way to identify and communicate chemicals in scientific settings.

Ionic Compounds

Ionic compounds consist of positive and negative ions bonded together by ionic bonds. These compounds are typically formed when metals react with nonmetals. For instance:

• Potassium nitrate ( KNO_3 ) consists of potassium ions ( K^+ ) and nitrate ions ( NO_3^- ).
• Sodium carbonate ( Na_2CO_3 ) includes sodium ions ( Na^+ ) and carbonate ions ( CO_3^{2-} ).

The formation of ionic compounds involves the transfer of electrons from the metal to the nonmetal, resulting in a stable electronic configuration. This electron transfer creates opposite charges that attract each other, forming a strong ionic bond.
Understanding ionic compounds is essential for decoding the systematic names and formulas used in chemistry.

Chemical Formulas

Chemical formulas are a shorthand way to represent the elements in a compound and the ratio in which they combine. Each element is represented by its chemical symbol, with numbers indicating the number of atoms of each element. For example:

• KNO_3 signifies one potassium (K), one nitrogen (N), and three oxygen (O) atoms.
• Mg(OH)_2 indicates one magnesium (Mg) atom and two hydroxide (OH) groups.

By understanding how chemical formulas are structured, you can determine not just the elements in a compound but also how they interact with each other.
Formulas like these provide essential insight into the compound's composition, which is crucial for writing chemical equations and understanding reactions.

Chemical Naming Conventions

Chemical naming conventions are systematic guidelines for creating a chemical name from a chemical formula. The IUPAC rules govern the naming of compounds to ensure consistency and clarity.

• For ionic compounds, names are derived from the cation (positive ion) followed by the anion (negative ion). For example, MgSO_4 is named Magnesium sulfate.
• Polyatomic ions, like carbonate (CO_3^{2-}) or hydroxide (OH^-), often have names you'll need to memorize as they don't follow regular naming conventions.

Following these conventions ensures that the name clearly indicates the compound's composition and charge balance.
This standardization is vital for clear communication in scientific literature and education, bridging gaps between common language and scientific terminology.