Question
FiQ Practice: The structures for butanone, mathrm(CH)_(3) mathrm(COCH)_(2) mathrm(CH)_(2) , and n -butane, mathrm(CH)_(3) mathrm(CH)_(2) mathrm(CH)_(2) mathrm(CH)_(3) , are show below. (A) *Identify the type of intermolecular forces in butanone and in n -butane. (B) *Butanone is much more soluble in mathrm(H)_(2) mathrm(O) than is n -butane. Account for this difference. (C) Predict the solubility of n -butane in toluene, the solvent we investigated in class today. Justify your response.
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Vincent
Master · Tutor for 5 years
Answer
(A) Step 1: Identify the type of intermolecular forces in butanone and in n-butane.Butanone (CH3COCH2CH3) is a polar molecule due to the presence of a carbonyl group (C=O). The oxygen atom is more electronegative than the carbon atom, creating a dipole moment. Therefore, the primary type of intermolecular force in butanone is dipole-dipole interaction.n-Butane (CH3CH2CH2CH3) is a nonpolar molecule because the electronegativity difference between carbon and hydrogen is very small, and the molecule is symmetric. Therefore, the primary type of intermolecular force in n-butane is London dispersion forces (also known as van der Waals forces).Answer: The type of intermolecular force in butanone is dipole-dipole interaction, and in n-butane is London dispersion forces.(B) Step 2: Account for the difference in solubility of butanone and n-butane in water.The solubility of a substance in water is determined by its ability to form hydrogen bonds with water molecules. Butanone, being a polar molecule, can form hydrogen bonds with water, making it more soluble. On the other hand, n-butane, being a nonpolar molecule, cannot form hydrogen bonds with water, making it less soluble.Answer: Butanone is more soluble in water than n-butane because it can form hydrogen bonds with water, while n-butane cannot.(C) Step 3: Predict the solubility of n-butane in toluene and justify your response.Toluene is a nonpolar solvent. According to the "like dissolves like" principle, nonpolar solvents dissolve nonpolar solutes well. Since n-butane is a nonpolar molecule, it should be soluble in toluene.Answer: n-Butane is likely to be soluble in toluene because both are nonpolar, and "like dissolves like".