Eugenol is one of the compounds responsible for the flavor...

Eugenol is one of the compounds responsible for the flavor of cloves. A 111 mg sample of eugenol is dissolved in $1.00 \mathrm{g}$ of chloroform $\left(K_{\mathrm{b}}=3.63^{\circ} \mathrm{C} / \mathrm{m}\right)$ increasing the boiling point of chloroform by $2.45^{\circ} \mathrm{C}$ Calculate eugenol's molar mass. Eugenol is $73.17 \% \mathrm{C}$ $7.32 \% \mathrm{H},$ and $19.51 \% \mathrm{O}$ by mass. What is the molecular formula of eugenol?

Eugenol is one of the compounds responsible for the flavor of cloves. A 111 mg sample of eugenol is dissolved in $1.00 \mathrm{g}$ of chloroform $\left(K_{\mathrm{b}}=3.63^{\circ} \mathrm{C} / \mathrm{m}\right)$
increasing the boiling point of chloroform by $2.45^{\circ} \mathrm{C}$ Calculate eugenol's molar mass. Eugenol is $73.17 \% \mathrm{C}$ $7.32 \% \mathrm{H},$ and $19.51 \% \mathrm{O}$ by mass. What is the molecular formula of eugenol?

Key Concepts

Boiling Point Elevation

Boiling point elevation is a colligative property where the addition of a nonvolatile solute to a solvent raises the boiling point. Its magnitude depends on the concentration of the solute rather than its identity, and it is quantified by the ebullioscopic constant (Kb) of the solvent.

Molality and Colligative Properties

Molality is defined as the number of moles of solute per kilogram of solvent, and it is used in calculations involving colligative properties such as boiling point elevation. These properties depend solely on the ratio of the number of solute particles to the amount of solvent, making molality a convenient concentration unit especially when temperature changes are involved.

Molar Mass Determination Using Colligative Properties

Molar mass can be determined by using the boiling point elevation method, where the observed temperature increase is linked to the molality of the solution. By calculating the number of moles of solute (from the elevation in boiling point and known Kb) and dividing the mass of the solute by this number, one obtains the molar mass.

Percent Composition and Empirical Formula

Percent composition provides the percentage by mass of each element within a compound. Using these values, one can calculate the number of moles of each element in a given mass (typically 100 grams) and determine the simplest whole-number ratio of the elements, which is the empirical formula.

Empirical and Molecular Formula Determination

Once the empirical formula is known, the molecular formula can be determined by comparing the empirical formula mass to the molar mass obtained experimentally. The molecular formula is an integer multiple of the empirical formula, providing the actual number of atoms in a molecule of the compound.

Transcript

Please give Ace some feedback