All compounds with the same empirical formula (which indicates the ratio of elements in a compound and not the exact number of atoms) have the same atomic composition. This means that these compounds contain the same proportion of elements by mass, although the number of atoms in the molecules may vary depending on the molecular structure.
Compounds that possess the same empirical formula and are therefore identical in terms of elements and their proportions by mass, include molecules with different structures such as isomers. Examples of compounds with the same empirical formula but distinct molecular structures include cyclohexane and cyclohexanol which contain six carbon atoms, 12 hydrogen atoms and six oxygen atoms, but the arrangement is different.
Other examples include the three different isomers of hexane, 2-methylpentane, 3-methylpentane, and 2,2-dimethylbutane, all of which have the same empirical formula (C5H12).
Table of Contents
For which of the following empirical formula is same?
The empirical formula for a chemical compound is the simplest whole number ratio of atoms of each element in the compound. Therefore, two compounds that have the same empirical formula have the same ratio of atoms of each element.
However, they may have different molecular structures and different chemical and physical properties. In addition, they may have different molecular formulas. For example, molecular and isomers have the same molecular formula, C3H6O, but different molecular structures and properties.
In which of the following pairs both have same empirical?
The atoms in a pair of elements have the same empirical formula when they have the same combination of atoms, regardless of the arrangement of the atoms or the mass of the atoms. For example, in a pair of elements such as carbon dioxide (CO2) and carbon monoxide (CO), although the mass of the carbon atom is different in each, the number of atoms is the same – one carbon atom and two oxygen atoms – and hence the empirical formula is the same for both.
Similarly, any two substances that contain the same elements in the same proportions will have the same empirical formula, regardless of the mass of individual atoms or the arrangement of the atoms.
Is empirical formula same in homologous series?
No, the empirical formula is not the same in homologous series. A homologous series is a series of compounds which all have the same functional group and similar chemical properties but can differ in their molecular structures.
In homologous series the empirical formula will remain the same, but the molecular formula will differ. For example, the alkanes are a homologous series of hydrocarbons that contain the same number of atoms, but the molecular formula increases as the number of carbon atoms increases.
The empirical formula for all alkanes is CnH2n+2, while the molecular formula increases linearly as the number of atoms increases, i. e. CH4, C2H6, C3H8, etc.
What has the same empirical formula but different?
The empirical formula is the simplest whole number ratio between the constituent atoms of a compound. Although two compounds may have the same empirical formula, they can often possess different structural formulas, and thus be entirely different.
For example, ethanol (C2H6O) and dimethyl ether (C2H6O) both have the same empirical formula of CH3O, but are distinct compounds due to their different structural formulas. Ethanol consists of a chain of two carbon molecules with a hydroxyl (-OH) group attached to one end, while dimethyl ether consists of two methyl groups (-CH3) flanking oxygen.
While these molecules have the same ratio of atoms, their structures and resulting chemical properties are vastly different.
What are the 3 steps to determining an empirical formula?
The three steps to determining an empirical formula are as follows:
1. Calculate the mass of each element present in the sample.
2. Divide each mass by the atomic mass of the element to calculate the number of moles of each element.
3. Divide each mole value by the smallest mole value to calculate the relative number of moles of each element in the empirical formula. The final result is the empirical formula of the compound.
Do all compounds with the same empirical formula have the same properties?
No, not all compounds with the same empirical formula have the same properties. The empirical formula is a representation of the ratio of elements in a compound, but it does not indicate the arrangement or type of bond that holds the elements together.
As a result, compounds with the same empirical formula can have different chemical properties, known as isomers. Isomers are compounds with the same molecular formula, but the atoms are arranged differently.
Chemically, the isomers may have very different properties, such as boiling point, melting point, chemical reactivity, and solubility. For example, the two compounds hexane and 2-methylpentane have the same molecular formula (C 6 H 14 ), but different properties; hexane is a liquid at room temperature and is highly volatile, whereas 2-methylpentane is a solid and is almost non-volatile at room temperature.
This demonstrates that compounds with the same empirical formula can have different physical and chemical properties due to the different arrangement of the atoms.
