Question

question 15 of 20
consider the table.

solid	triple point	normal melting point
b	0.35 atm, - 17 °c	50 °c
c	0.0072 atm, 88 °c	89 °c

based on the data in the table, which solids will melt under applied pressure?
□ b
□ c
□ a

Explanation:

Step1: Recall melting - pressure relationship

For substances with a negative slope of the solid - liquid phase boundary (on a phase diagram), increasing pressure causes melting. This occurs when the normal melting point is lower than the triple - point temperature.

Step2: Analyze solid A

Solid A has a triple - point temperature of $124^{\circ}C$ and a normal melting point of $108^{\circ}C$. Since the normal melting point is lower than the triple - point temperature, increasing pressure will cause it to melt.

Step3: Analyze solid B

Solid B has a triple - point temperature of $- 17^{\circ}C$ and a normal melting point of $50^{\circ}C$. Since the normal melting point is higher than the triple - point temperature, increasing pressure will not cause it to melt.

Step4: Analyze solid C

Solid C has a triple - point temperature of $88^{\circ}C$ and a normal melting point of $89^{\circ}C$. Since the normal melting point is higher than the triple - point temperature, increasing pressure will not cause it to melt.

Answer:

A