A materials scientist investigates the mechanical response of three unknown…
PHYSICS · Multi-part · ISC · Physics · Properties of Bulk Matter · Elastic moduli and Hooke's law
Problem
A materials scientist investigates the mechanical response of three unknown homogeneous samples (A, B, and C) that are each known to be pure and in a single phase at 25 °C. To compare their compressibilities, the scientist applies an additional 50 atm of external pressure to each 10.0 cm³ sample and measures the fractional volume decrease ΔV/V0. The results are given below.
Sample | ΔV/V0 upon +50 atm
————|———————————————
A | 0.150
B | 0.0070
C | 0.00045
(a) Identify which sample is most likely a gas, which is most likely a liquid, and which is most likely a solid. Justify your identifications using the data.
(b) Rank the samples in order of increasing average intermolecular distance. Explain how the measured compressibilities support your ranking.
(c) Discuss how the relative strengths of intermolecular forces in the three samples correlate with both their compressibilities and their likely phases.
(d) Propose one additional experimental measurement—other than compressibility—that could help confirm the phase assignment of samples A, B, and C. Describe what results you would expect for each sample and why.