Two substances have the same molecular and empirical formulas. Does this mean that they must be the same compound?

Verified step by step guidance

1. Understand the definitions: The molecular formula of a compound shows the actual number of atoms of each element in a molecule. The empirical formula is the simplest whole-number ratio of atoms of each element in the compound.
2. Consider the relationship: If two substances have the same molecular formula, they contain the same number and type of atoms. If they also have the same empirical formula, their elemental composition is expressed in the same simplest ratio.
3. Analyze exceptions: Despite having the same molecular and empirical formulas, substances can differ if they are isomers. Isomers are compounds with the same molecular formula but different arrangements of atoms in space, leading to different properties.
4. Evaluate the context: If the substances are not isomers, and there is no indication of differing structural arrangements, then they are likely the same compound.
5. Conclude: Two substances with the same molecular and empirical formulas are generally the same compound unless they are different types of isomers.

Key Concepts

Molecular Formula

The molecular formula of a compound indicates the actual number of atoms of each element present in a molecule. It provides specific information about the composition of the compound, such as C6H12O6 for glucose, which shows that there are six carbon, twelve hydrogen, and six oxygen atoms in each molecule.

Empirical Formula

The empirical formula represents the simplest whole-number ratio of the elements in a compound. For example, the empirical formula for glucose (C6H12O6) is CH2O, indicating that for every carbon atom, there are two hydrogen atoms and one oxygen atom, regardless of the actual number of atoms in the molecule.

Isomerism

Isomerism occurs when two or more compounds have the same molecular and empirical formulas but differ in the arrangement of atoms or the connectivity of their structures. These variations can lead to different physical and chemical properties, meaning that compounds with identical formulas can still be distinct substances.