Problem 76 - Chemistry: The Central Science

Question

Provide the name or chemical formula, as appropriate, for each of the following acids: (a) hydroiodic acid, (b) chloric acid, (c) nitrous acid, (d) \(\mathrm{H}_{2} \mathrm{CO}_{3}\), (e) \(\mathrm{HClO}_{4}\), (f) \(\mathrm{CH}_{3} \mathrm{COOH}\).

Step-by-Step Solution

Answer

(a) hydroiodic acid: HI, (b) chloric acid: HClO₃, (c) nitrous acid: HNO₂, (d) \(\mathrm{H}_{2} \mathrm{CO}_{3}\): carbonic acid, (e) \(\mathrm{HClO}_{4}\): perchloric acid, (f) \(\mathrm{CH}_{3} \mathrm{COOH}\): acetic acid.

Step 1: (a) hydroiodic acid

To find the chemical formula for hydroiodic acid, we need to recognize the fact that it is a binary acid (composed of two elements). In this case, the elements are hydrogen (H) and iodine (I). The formula for hydroiodic acid can be written as HI.

Step 2: (b) chloric acid

For chloric acid, we need to identify the polyatomic ion, which in this case is chlorate (ClO₃⁻). The hydrogen ion (H⁺) combines with the chlorate ion to form chloric acid. Therefore, the chemical formula for chloric acid is HClO₃.

Step 3: (c) nitrous acid

For nitrous acid, the polyatomic ion is nitrite (NO₂⁻). The hydrogen ion (H⁺) combines with the nitrite ion to form nitrous acid. Thus, the chemical formula for nitrous acid is HNO₂.

Step 4: (d) \(\mathrm{H}_{2} \mathrm{CO}_{3}\)

To find the name of this acid, we need to identify the polyatomic ion. The polyatomic ion here is carbonate (CO₃²⁻). Carbonate ion combined with two hydrogen ions (2H⁺) form this particular acid. Therefore, the name of the acid is carbonic acid.

Step 5: (e) \(\mathrm{HClO}_{4}\)

In this case, the polyatomic ion is perchlorate (ClO₄⁻). The hydrogen ion (H⁺) combines with the perchlorate ion to form the acid. The name of this acid is perchloric acid.

Step 6: (f) \(\mathrm{CH}_{3} \mathrm{COOH}\)

In this case, we have a carboxylic acid. The formula \(\mathrm{CH}_{3} \mathrm{COOH}\) gives us acetic acid, which is a weak organic acid commonly used in the household as vinegar. As a result, the name of this acid is acetic acid.

Key Concepts

Binary Acids

Binary acids are a type of acid that consist of only two elements. One of the elements is always hydrogen, and the other is a non-metal. Common examples include hydrochloric acid (HCl) and hydroiodic acid (HI). How Binary Acids Are Named:

• The name begins with "hydro-", which hints at the presence of hydrogen.
• Next comes the stem of the non-metal's name with the ending "-ic".
• The word "acid" is added at the end.

For instance, in the case of hydroiodic acid, the name indicates the elements are hydrogen and iodine, resulting in the formula HI. Understanding how to identify and name binary acids helps in writing their chemical formulas accurately.

Polyatomic Ions

Polyatomic ions are ions that consist of two or more atoms bonded together that function as a single charged entity. They are crucial in naming and formulating certain acids. Examples of common polyatomic ions include:

• Chlorate (\(\mathrm{ClO}_3^-\)): forms chloric acid (\(\mathrm{HClO}_3\))
• Perchlorate (\(\mathrm{ClO}_4^-\)): forms perchloric acid (\(\mathrm{HClO}_4\))
• Nitrite (\(\mathrm{NO}_2^-\)): forms nitrous acid (\(\mathrm{HNO}_2\))
• Carbonate (\(\mathrm{CO}_3^{2-}\)): forms carbonic acid (\(\mathrm{H}_2\mathrm{CO}_3\))

Naming acids from polyatomic ions usually involves modifying the name of the ion. Typically, an "-ate" suffix turns into "-ic" and "-ite" becomes "-ous" when naming the acid. This systematic approach aids in converting the ion's name into the acid's name effectively.

Chemical Formulas

Chemical formulas are a concise way of representing chemical substances using symbols and subscripts. They are essential in chemistry to convey information about the elements in a compound and their proportions.How to Read Chemical Formulas:

• Each symbol represents an element present in the compound.
• Subscripts indicate the number of atoms of each element in the compound.
• If no subscript is present, it is understood as 1.

For example, in \(\mathrm{H}_2\mathrm{CO}_3\), the formula reveals there are two hydrogen atoms, one carbon atom, and three oxygen atoms. Understanding chemical formulas helps interpret the composition of acids and other compounds in chemistry.

Organic Acids

Organic acids are acids with a carbon backbone and are often found in biological systems. They typically contain the carboxyl group (-COOH), which is responsible for their acidic properties.Features of Organic Acids:

• They contain carbon atoms and are based on carbon structures.
• The presence of the carboxyl group (\(\mathrm{-COOH}\)) is common in these acids.
• They are generally weaker than inorganic acids like hydrochloric acid.

An example is acetic acid (\(\mathrm{CH}_3\mathrm{COOH}\)), known for its role in vinegar. Organic acids are essential in both industrial applications and biological processes, demonstrating their versatility and importance in chemistry and daily life.