To determine which substance most likely has the highest boiling point among calcium chloride (CaCl₂), methanol (CH₃OH), and carbon tetrachloride (CCl₄), we need to consider the types of bonding and intermolecular forces present in each substance.
1. Calcium chloride (CaCl₂):
- Type of Bonding: Ionic bonding.
- Intermolecular Forces: Strong electrostatic forces between the positively charged calcium ions (Ca²⁺) and negatively charged chloride ions (Cl⁻).
- Boiling Point: Ionic compounds typically have very high boiling points due to the strength of these electrostatic forces.
2. Methanol (CH₃OH):
- Type of Bonding: Polar covalent bonding.
- Intermolecular Forces: Hydrogen bonding (due to the presence of an -OH group) and dipole-dipole interactions.
- Boiling Point: Hydrogen bonds are relatively strong among intermolecular forces for covalent compounds, but they are generally weaker than ionic bonds. Hence, methanol will have a moderate boiling point.
3. Carbon tetrachloride (CCl₄):
- Type of Bonding: Nonpolar covalent bonding.
- Intermolecular Forces: London dispersion forces (Van der Waals forces).
- Boiling Point: These forces are weaker compared to hydrogen bonds and especially ionic bonds, so carbon tetrachloride will have a relatively low boiling point.
Comparing the three:
- Calcium chloride (CaCl₂) has strong ionic bonds, leading to the highest boiling point among the substances.
- Methanol (CH₃OH) has hydrogen bonds and some dipole-dipole interactions but is not as strong as ionic bonds, so its boiling point is moderate.
- Carbon tetrachloride (CCl₄) has weak London dispersion forces, leading to the lowest boiling point.
Therefore, the substance with the highest boiling point is calcium chloride (CaCl₂).
