Problem 80 - Chemistry: The Central Science in SI Units, Global Edition

Question

Assume that you encounter the following sentences in your reading. What is the chemical formula for each substance mentioned? (a) Sodium hydrogen carbonate is used as a deodorant. (b) Calcium hypochlorite is used in some bleaching solutions. (c) Hydrogen cyanide is a very poisonous gas. (d) Magnesium hydroxide is used as a cathartic. (e) Tin(II) fluoride has been used as a fluoride additive in toothpastes. (f) When cadmium sulfide is treated with sulfuric acid, fumes of hydrogen sulfide are given off.

Step-by-Step Solution

Answer

The chemical formulas for the mentioned substances are as follows: (a) Sodium hydrogen carbonate: NaHCO3 (b) Calcium hypochlorite: Ca(ClO)2 (c) Hydrogen cyanide: HCN (d) Magnesium hydroxide: Mg(OH)2 (e) Tin(II) fluoride: SnF2 (f) Cadmium sulfide: CdS

Step 1: (a) Sodium hydrogen carbonate

Sodium hydrogen carbonate consists of sodium (Na), hydrogen (H), and carbonate (CO3). The ions included are Na+ (from sodium) and HCO3- (from hydrogen carbonate). The chemical formula is formed by balancing the charges and combining the ions: NaHCO3.

Step 2: (b) Calcium hypochlorite

Calcium hypochlorite is composed of calcium (Ca) and hypochlorite (ClO). The ions involved are Ca2+ (from calcium) and ClO- (from hypochlorite). Balancing the charges, the chemical formula is: Ca(ClO)2.

Step 3: (c) Hydrogen cyanide

Hydrogen cyanide includes hydrogen (H) and cyanide (CN). The ions involved are H+ (from hydrogen) and CN- (from cyanide). The chemical formula is: HCN.

Step 4: (d) Magnesium hydroxide

Magnesium hydroxide consists of magnesium (Mg) and hydroxide (OH). The ions involved are Mg2+ (from magnesium) and OH- (from hydroxide). Balancing the charges results in the chemical formula: Mg(OH)2.

Step 5: (e) Tin(II) fluoride

Tin(II) fluoride consists of tin (Sn) and fluoride (F). Tin in this case has a +2 charge (indicated by the Roman numerals), so the ion is Sn2+(from tin). Fluoride is F- (from fluorine). Combining and balancing the charges gives the chemical formula: SnF2.

Step 6: (f) Cadmium sulfide

Cadmium sulfide is composed of cadmium (Cd) and sulfide (S). The ions involved are Cd2+ (from cadmium) and S2- (from sulfide). The chemical formula is: CdS.

Key Concepts

Chemical Compounds

Chemical compounds are materials made up of two or more elements chemically bonded together. These can be inorganic or organic, containing a structured arrangement of atoms. The molecules within a chemical compound share atoms that are bound tightly by chemical bonds, resulting in substances with specific characteristics and properties.
In the realm of inorganic chemistry, you'll frequently find chemical compounds formed through bonds between metals and non-metals, evidenced by compounds like magnesium hydroxide (Mg(OH)₂) or calcium hypochlorite (Ca(ClO)₂).

• Element Composition: Chemical compounds have specific elements combined in fixed ratios. For instance, in water (H₂O), there are always two hydrogen atoms for every one oxygen atom.
• Distinguishing Properties: Compounds possess unique properties distinct from the elements that compose them. This is why sodium hydrogen carbonate, common in deodorants, has different properties than pure sodium or pure carbon.

Chemical formulas are the way we express the composition of a compound in symbols showcasing the elements and their ratios. Understanding these formulas is essential, as it allows us to comprehend complex chemical interactions and reactions.

Ionic Bonds

Ionic bonds are a type of chemical bond formed through the electrostatic attraction between two oppositely charged ions. These bonds are common in inorganic compounds, where metals and non-metals interact.
For example, consider the compound tin(II) fluoride (SnF₂). In this compound, tin carries a positive charge ( \(\text{Sn}^{2+}\) ) while fluoride ions, derived from fluorine, carry a negative charge ( \(\text{F}^{-}\)). This contrast in charges creates a strong force, pulling the ions together into a stable ionic lattice.

• Formation of Ionic Bonds: The process involves the transfer of electrons from one atom, typically a metal, to another, usually a non-metal. This transfer leads to the formation of ions with complete electron shells.
• Properties: Ionic compounds are often solid at room temperature, have high melting points, and can conduct electricity when dissolved in water. These properties are due to the strong interactions between the ions.

Recognizing the nature of ionic bonds can help you predict and understand the properties of numerous chemical compounds, such as those you might encounter in toothpaste or cleaning agents.

Inorganic Chemistry

Inorganic chemistry focuses on the properties and behaviors of inorganic compounds, which lack carbon-hydrogen bonds that characterize organic molecules. This branch of chemistry is broad, covering a variety of substances from metals to minerals.
Calcium hypochlorite (Ca(ClO)₂), used in bleaching solutions, exemplifies inorganic chemistry's scope, showcasing the way metals and non-metals form complex structures with varied applications.

• Diverse Structures: Inorganic compounds can have a range of structural forms, including crystals, metals, salts, and minerals. This diversity is due to the versatility of bonding and arrangement of atoms in these compounds.
• Applications: The field of inorganic chemistry is crucial in the development of materials with everyday uses, from cleaning products to construction materials, highlighting the practical importance of these compounds.

A thorough understanding of inorganic chemistry principles is key to advancing in fields like materials science, metallurgy, and environmental science, enabling the creation of solutions to complex real-world problems.