Question

The composition of a given pure compound is always ________ no matter what the source of the compound.

Short answer

The composition of a given pure compound is always \(\textbf{constant}\), no matter what the source of the compound.

Step-by-step solution

Define Pure Compound#

A pure compound is a substance that consists of two or more elements chemically bonded together in a fixed proportion. Examples of pure compounds are water (H2O), carbon dioxide (CO2), and salt (NaCl). The proportion of elements in a pure compound always remains the same, no matter where the compound is found.

Determine the Correct Term#

In the context of the given sentence, the missing term should emphasize the fact that the composition of a pure compound is consistent and does not change. The correct term for this context is "constant."

Complete the Sentence#

Now that we have determined the correct word to fill in the blank, the completed sentence should read: "The composition of a given pure compound is always constant, no matter what the source of the compound."

Key concepts

Pure Compounds

Pure compounds are a class of substances that have a fixed and uniform chemical structure. They consist of two or more elements that are chemically bonded in precise, unchanging ratios. This characteristic makes them distinguishable from mixtures, where the composition can vary. When we think of pure compounds, imagine substances like water (H₂O), carbon dioxide (CO₂), and sodium chloride (NaCl). Each of these has a specific formula, which represents the exact proportion of atoms involved.

• Water is always made up of two hydrogen atoms for each oxygen atom.
• Carbon dioxide always contains one carbon atom bonded to two oxygen atoms.
• Salt, or sodium chloride, comprises an equal number of sodium and chloride ions.

Because their composition doesn’t change regardless of where you find them, pure compounds are said to have a constant composition. This is why they play a crucial role in scientific studies and industrial applications, where consistency and predictability are essential.

Element Proportion

Element proportion refers to the fixed ratio of elements within a pure compound. This means each element in a compound contributes a specific number of atoms or molecules that remains unchanged. Understanding this concept of unchanging proportion helps us predict the properties and reactions of compounds.

• For example, every molecule of water always consists of two hydrogen atoms and one oxygen atom, represented by the formula H₂O.
• This fixed proportionality is why we can predict that water will evaporate and freeze at certain temperatures, given specific pressure conditions.

The principle of a constant element proportion gives pure compounds their unique characteristics.
This unalterable ratio keeps their chemical properties consistent, making them reliable substances for various uses.

Chemical Bonding

Chemical bonding is the force that holds the elements of a pure compound together. These bonds are essential for creating stability and determining the structure of the compound. There are several types of chemical bonds, including ionic, covalent, and metallic bonds.

• Ionic bonds, such as those in sodium chloride (NaCl), form when electrons are transferred from one atom to another, creating ions that attract each other.
• Covalent bonds occur when atoms, like those in water (H₂O) or carbon dioxide (CO₂), share electrons to achieve stability.
• Metallic bonds are found in metals, where electrons are shared among a lattice of atoms, providing properties like conductivity.

Understanding these bonds helps explain why compounds behave as they do. Each type of bond contributes differently to the strength and properties of the compound.
This knowledge is crucial in fields ranging from chemistry to materials science, influencing everything from new drug development to the creation of new materials.