Choose the substance with the highest viscosity: BeCl2, SbBr3, IF2, AsI3, OF2 QUESTION 40: Choose the substance with the highest surface tension: CH3CH2Cl, CH3CH2CH2CH2, CH3CH2CH2OH, HOCH2CH2OH, CH2Br2
The Correct Answer and Explanation is:
Highest Viscosity:
To determine which substance has the highest viscosity, we need to consider factors like molecular size, intermolecular forces, and structure. Viscosity increases with stronger intermolecular forces and larger molecules.
- BeCl2: Beryllium chloride has ionic bonds, but it has a linear structure, which reduces the intermolecular attraction. As a result, its viscosity is relatively low compared to others.
- SbBr3: Antimony tribromide is a larger molecule than BeCl2, with relatively strong van der Waals forces, but it’s still less viscous compared to substances that have hydrogen bonding.
- IF2: Iodine difluoride has a relatively low molecular mass and weak intermolecular forces (mainly dispersion forces). It would have a lower viscosity compared to substances with stronger intermolecular attractions.
- AsI3: Arsenic triiodide is a molecular compound that exhibits van der Waals forces. It has a somewhat high molecular mass, but the forces at play here are weaker than hydrogen bonds.
- OF2: Oxygen difluoride is a highly electronegative molecule with polar bonds. Its high electronegativity leads to dipole-dipole interactions, increasing its viscosity more than the others, but still not as much as a hydrogen-bonded compound.
Answer: OF2 has the highest viscosity due to its polar nature and stronger intermolecular forces compared to the others, but it’s still weaker than a hydrogen-bonded compound.
Highest Surface Tension:
Surface tension is influenced by the strength of intermolecular forces at the liquid-air interface. Hydrogen bonding and polarity contribute to a high surface tension.
- CH3CH2Cl: Ethyl chloride has dipole-dipole interactions, but no hydrogen bonding. This leads to a moderate surface tension.
- CH3CH2CH2CH2: Butane is a nonpolar molecule with only dispersion forces. Nonpolar molecules tend to have lower surface tension because they don’t exhibit strong intermolecular forces.
- CH3CH2CH2OH: 1-Propanol has hydrogen bonding due to the hydroxyl group (-OH). Hydrogen bonding significantly increases surface tension.
- HOCH2CH2OH: Ethylene glycol has two hydroxyl groups, which means even stronger hydrogen bonding. This will give it a very high surface tension compared to other substances in the list.
- CH2Br2: Dibromomethane has dipole-dipole forces due to its polar nature but doesn’t have hydrogen bonding. Its surface tension will be moderate compared to those with hydrogen bonding.
Answer: HOCH2CH2OH (ethylene glycol) has the highest surface tension because it has the strongest intermolecular hydrogen bonds due to the two -OH groups, resulting in a high surface tension.
