During a lecture demonstration three different gases are allowed to flow into…
CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
During a lecture demonstration three different gases are allowed to flow into identical rigid containers. For each gas, the instructor measures several sample masses while simultaneously counting the amount (in moles) that entered. When the combined data are plotted on a single set of axes (mass versus moles), three distinct straight lines are observed with the following slopes:
• Line X: 18 g mol⁻¹
• Line Y: 32 g mol⁻¹
• Line Z: 44 g mol⁻¹
The possible identities of the gases are water vapour (H₂O), oxygen (O₂), and carbon dioxide (CO₂).
(a) Match each line (X, Y, Z) to the correct gas. Justify your assignments.
(b) For the gas represented by line Y, calculate the mass that would be present when 0.350 mol occupies the container.
(c) Suppose a future measurement for oxygen produced the ordered pair (0.250 mol, 6.8 g). Explain how the plotted point could be used to evaluate the purity of the oxygen sample.