Final answer:
Extraction of salicylic acid and naphthalene uses the principle of differing solubilities with sodium bicarbonate to separate them. Sublimation purifies naphthalene by directly converting it from solid to vapor. Empirical and molecular formulas of compounds are derived from combustion analysis, and percent yield of sodium bicarbonate purification is calculated based on solubility at different temperatures.
Step-by-step explanation:
The extraction of a mixture of salicylic acid and naphthalene using saturated aqueous sodium bicarbonate and water takes advantage of their different solubility properties. Salicylic acid is an acidic compound and reacts with sodium bicarbonate to form a water-soluble salt, thus removing it from the nonpolar naphthalene. Water, being polar, is not an effective solvent for naphthalene, which is nonpolar. Therefore, naphthalene remains undissolved when the bicarbonate solution is used. When the mixture is subjected to the process of sublimation, naphthalene, having a high vapor pressure, can turn directly from a solid into a vapor, leaving behind impurities. This is useful in purifying crude naphthalene, as only the naphthalene vaporizes and then re-solidifies on a cool surface, separate from other non-sublimable impurities.
To calculate the empirical and molecular formulas of compounds, combustion analysis is typically used. For example, a sample of naphthalene that produces a certain mass of CO₂ upon combustion can be used to determine the empirical formula and, with the molecular mass, also the molecular formula of naphthalene. Similarly, a compound composed of boron and hydrogen would also have its empirical and molecular formulas determined from the amounts of products formed during combustion.
In a purification process like that of sodium bicarbonate, the percentage yield can be calculated by comparing the amount of sodium bicarbonate recovered after cooling and filtration to the total amount that could have been dissolved based on its solubility at different temperatures.