Question

Water is a polar solvent and carbon tetrachloride \(\left(\mathrm{CCl}_{4}\right)\) is a nonpolar solvent. In which solvent is each of the following more likely to be soluble? a. \(\mathrm{NaNO}_{3}\), ionic b. \(\mathrm{I}_{2}\), nonpolar c. sucrose (table sugar), polar d. gasoline, nonpolar

Short answer

a. Water b. carbon tetrachloride c. Water d. carbon tetrachloride

Step-by-step solution

Identify the nature of each substance

Determine whether each substance is polar, nonpolar, or ionic. a. \(\text{NaNO}_{3}\): Ionic b. \(\text{I}_{2}\): Nonpolar c. Sucrose: Polar d. Gasoline: Nonpolar

Understand the solvent properties

Water is a polar solvent. Carbon tetrachloride (\(\text{CCl}_{4}\)) is a nonpolar solvent.

Apply 'like dissolves like' principle

Substances tend to dissolve in solvents that have similar polarity. \(\text{NaNO}_{3}\), being ionic, will dissolve in polar solvents. \(\text{I}_{2}\) and gasoline, both nonpolar, will dissolve in nonpolar solvents. Sucrose, being polar, will dissolve in polar solvents.

Assign each substance to the appropriate solvent

a. \(\text{NaNO}_{3}\) will dissolve in water (polar solvent). b. \(\text{I}_{2}\) will dissolve in carbon tetrachloride (nonpolar solvent). c. Sucrose will dissolve in water (polar solvent). d. Gasoline will dissolve in carbon tetrachloride (nonpolar solvent).

Key concepts

polar solvents

Polar solvents have molecules with a positive end and a negative end, creating an overall dipole moment. This dipole allows polar solvents to interact with and dissolve other polar substances and ionic compounds. Water is the most common example of a polar solvent. Because of water's polar nature, it has strong hydrogen bonds and a high specific heat capacity.

nonpolar solvents

Nonpolar solvents, in contrast to polar solvents, have molecules that do not have significant charge separation. No dipole moment is created in nonpolar molecules, which means they cannot form strong interactions with polar molecules or ionic compounds. Nonpolar solvents are excellent at dissolving other nonpolar substances. An example of a nonpolar solvent is carbon tetrachloride (CCl4).

like dissolves like principle

The 'like dissolves like' principle is a guideline used to predict the solubility of substances in different solvents. It states that substances with similar polarities are more likely to dissolve in each other.

• Polar substances dissolve in polar solvents.
• Nonpolar substances dissolve in nonpolar solvents.
• Ionic compounds typically dissolve better in polar solvents.

This principle helps us understand why water (polar) can dissolve salt (ionic) but not oil (nonpolar).

ionic compounds

Ionic compounds, like NaNO3, are composed of positively and negatively charged ions. These compounds tend to dissolve well in polar solvents due to the solvent's ability to stabilize the ions. When an ionic compound dissolves, the ions separate and are surrounded by solvent molecules, each oriented to align with the appropriate charge.

polarity

Polarity refers to the distribution of electrical charges over the atoms joined by the bond. A molecule with significant charge differences between its atoms will be polar. This feature is determined by the differences in electronegativity between the atoms involved.

• Polar molecules have distinct positive and negative ends.
• Nonpolar molecules have no significant charge imbalance.

Polarity is a key factor in determining solubility and chemical behavior of substances.