Question

the surface tension of isopropanol in air has a value of 23.00 units and the surface tension of water in air is 72.80 units. which two statements are true?
a. isopropanol will have a lower boiling point than water because the forces between the molecules are smaller.
b. isopropanol will have a flatter meniscus than water because the forces between the molecules are smaller.
c. isopropanol will have a higher boiling point than water because the forces between the molecules are greater.
d. isopropanol will have a more curved meniscus than water because the forces between the molecules are greater.

Explanation:

• For boiling point: Surface tension is related to intermolecular forces. Higher surface tension (like in water, 72.80 units) implies stronger intermolecular forces. Stronger intermolecular forces require more energy to break, so water has a higher boiling point. Isopropanol has lower surface tension (23.00 units), so weaker intermolecular forces and a lower boiling point. So, statement A is correct and statement C is wrong.
• For meniscus: A flatter meniscus is associated with weaker intermolecular forces. Since isopropanol has weaker intermolecular forces (lower surface tension), it will have a flatter meniscus compared to water. So, statement B is correct and statement D is wrong.

Answer:

A. Isopropanol will have a lower boiling point than water because the forces between the molecules are smaller.
B. Isopropanol will have a flatter meniscus than water because the forces between the molecules are smaller.