Question

Find the item in column 2 that best explains or completes the statement or question in column 1 Column 1 (1) \(1 \mathrm{amu}\) (2) 1008 amu (3) mass of the "average" atom of an element (4) number of carbon atoms in \(12.01 \mathrm{~g}\) of carbon (5) \(6.022 \times 10^{23}\) molecules (6) total mass of all atoms in 1 mole of a compound (7) smallest whole-number ratio of atoms present in a molecule (8) formula showing actual number of atoms present in a molecule (9) product formed when any carbon-containing compound is burned in \(\mathrm{O}_{2}\) (10) have the same empirical formulas, but different molecular formulas Column 2 (a) \(6.022 \times 10^{23}\) (b) atomic mass (c) mass of 1000 hydrogen atoms (d) benzene, \(\mathrm{C}_{6} \mathrm{H}_{6},\) and acetylene, \(\mathrm{C}_{2} \mathrm{H}_{2}\) (e) carbon dioxide (f) empirical formula (g) \(1.66 \times 10^{-24} \mathrm{~g}\) (h) molecular formula (i) molar mass (j) 1 mole

Short answer

The matched pairs for the statements or questions in column 1 with their best explanations or completions in column 2 are as follows: (1) $1 \mathrm{amu}$ - (g) $1.66 \times 10^{-24} \mathrm{~g}$ (2) 1008 amu - (c) mass of 1000 hydrogen atoms (3) mass of the "average" atom of an element - (b) atomic mass (4) number of carbon atoms in $12.01 \mathrm{~g}$ of carbon - (a) $6.022 \times 10^{23}$ (5) $6.022 \times 10^{23}$ molecules - (j) 1 mole (6) total mass of all atoms in 1 mole of a compound - (i) molar mass (7) smallest whole-number ratio of atoms present in a molecule - (f) empirical formula (8) formula showing actual number of atoms present in a molecule - (h) molecular formula (9) product formed when any carbon-containing compound is burned in $\mathrm{O}_{2}$ - (e) carbon dioxide (10) have the same empirical formulas, but different molecular formulas - (d) benzene, $\mathrm{C}_{6} \mathrm{H}_{6},$ and acetylene, $\mathrm{C}_{2} \mathrm{H}_{2}$

Step-by-step solution

Match statement (1) to its best explanation or completion

In this step, look for the definition or units of 1 amu (atomic mass unit) in column 2. From the list, we can see that the term 1 amu is represented by the expression \(1.66 \times 10^{-24} \mathrm{~g}\), which is item (g) in column 2.

Match statement (2) to its best explanation or completion

In this step, look for the meaning of 1008 amu in column 2. The expression 1008 amu represents the mass of 1000 hydrogen atoms (1 amu is the approximate mass of one hydrogen atom). This corresponds to item (c) in column 2.

Match statement (3) to its best explanation or completion

In this step, look for the definition of the mass of the "average" atom of an element in column 2. The mass of the "average" atom of an element is called the atomic mass, which is item (b) in column 2.

Match statement (4) to its best explanation or completion

In this step, look for the number of carbon atoms present in 12.01 g of carbon in column 2. This quantity is the same as Avogadro's number, which is represented by the expression \(6.022 \times 10^{23}\), and is item (a) in column 2.

Match statement (5) to its best explanation or completion

In this step, look for the meaning of \(6.022 \times 10^{23}\) molecules in column 2. This number represents one mole of molecules and is item (j) in column 2.

Match statement (6) to its best explanation or completion

In this step, look for the definition of the total mass of all atoms in 1 mole of compound in column 2. The total mass of all atoms in one mole of a compound is called the molar mass, which is item (i) in column 2.

Match statement (7) to its best explanation or completion

In this step, look for the term that defines the smallest whole-number ratio of atoms present in a molecule in column 2. This term is known as the empirical formula, which is item (f) in column 2.

Match statement (8) to its best explanation or completion

In this step, look for the term that defines the formula showing the actual number of atoms present in a molecule in column 2. This term is known as the molecular formula, which is item (h) in column 2.

Match statement (9) to its best explanation or completion

In this step, look for the product formed when any carbon-containing compound is burned in \(\mathrm{O}_{2}\) in column 2. The product from this reaction is carbon dioxide, which is item (e) in column 2.

Match statement (10) to its best explanation or completion

In this step, look for compounds that have the same empirical formulas but different molecular formulas in column 2. An example of such compounds is benzene, \(\mathrm{C}_{6} \mathrm{H}_{6},\) and acetylene, \(\mathrm{C}_{2} \mathrm{H}_{2}\), which can be found in item (d) in column 2.

Key concepts

Atomic Mass

Atomic mass is a fundamental concept in chemistry that plays a crucial role in understanding the composition of elements. It refers to the mass of a single atom of a chemical element. This mass is expressed in atomic mass units (amu), where 1 amu is defined as one-twelfth of the mass of a carbon-12 atom. Understanding atomic mass allows chemists to predict the behavior of atoms in chemical reactions and their interactions with other atoms.

Atomic mass is generally relative, focusing on the average mass of atoms in a sample that contains isotopes of an element in their natural abundance. This is why the atomic mass of an element on the periodic table often looks like a whole number with decimals, like 12.01 for carbon. Calculating the atomic mass involves taking into account the different isotopes of an element and their respective masses and abundance.

• For example, hydrogen has an atomic mass of approximately 1.008 amu.
• Carbon has an atomic mass of about 12.01 amu.

Molar Mass

Molar mass extends the concept of atomic mass to a macroscopic scale and is defined as the mass of one mole of a substance. A mole is a quantity known to contain Avogadro's number of entities, specifically, \(6.022 \times 10^{23}\) molecules or atoms. Molar mass is expressed in grams per mole (g/mol).

To find the molar mass of a compound, you add up the atomic masses of all the atoms present in a molecule of that compound, according to their respective stoichiometry. For example, to calculate the molar mass of water \(H_2O\), you would add the atomic masses of two hydrogen atoms and one oxygen atom, which approximately equals \(18.02\) g/mol.

• This allows us to convert between moles and grams, a fundamental step in stoichiometry.
• Essential for balancing chemical equations and predicting how much of a product a reaction will yield.

Empirical Formula

The empirical formula of a compound provides the simplest whole-number ratio of the elements within it. This does not necessarily reflect the actual number of atoms present in a molecule but rather simplifies the ratio of these atoms. For instance, hydrogen peroxide is composed of hydrogen and oxygen, and its empirical formula is HO, indicating a 1:1 ratio of these elements. However, its molecular formula is \(H_2O_2\).

Empirical formulas are particularly useful for identifying compounds in situations where the exact molecular formula might be complex or uncertain. For substances with complicated structures or lack of precise molecular data, the empirical formula offers a simple way to gain insights into the composition of the compound.

• Helps in understanding the composition of unknown substances discovered during chemical analysis.
• Vital in analyzing and comparing chemical reactions where the proportions need to be managed.

Molecular Formula

A molecular formula exhibits the actual number of atoms of each element present in a molecule of a compound. Unlike the empirical formula, which only shows the simplest ratio of elements, the molecular formula gives a richer description of a compound's composition. It highlights the specific number of atoms involved and is essential for understanding the structure and specific properties of a compound.

For example, glucose has the empirical formula \(CH_2O\) and the molecular formula \(C_6H_{12}O_6\). These formulas suggest that every molecule of glucose contains six carbon, twelve hydrogen, and six oxygen atoms. The molecular formula not only provides clarity on the proportions within the molecule but also informs about its potential interactions and stability.

• Crucial for understanding the unique chemical behavior and reactivity of a compound.
• Used extensively in organic chemistry to deduce structural formulas and identify isomers.