Question

equimolar samples of ch₄(g) and c₂h₆(g) are in identical containers at the same temperature. the c₂h₆(g) deviates much more from ideal behavior than the ch₄(g) does. which of the following best helps explain this deviation?
a c₂h₆ molecules have more hydrogen bonding than ch₄ molecules do.
b c₂h₆ molecules have a larger, more polarizable electron cloud than ch₄ molecules do.
c the c₂h₆ molecules have a greater average kinetic energy than the ch₄ molecules have.
d the c₂h₆ molecules have a greater average speed than the ch₄ molecules have.

Explanation:

1. Hydrogen - bonding: Neither \(CH_4\) nor \(C_2H_6\) can form hydrogen - bonding since they do not have \(H\) bonded to \(N\), \(O\), or \(F\), so option A is incorrect.
2. Polarizability: \(C_2H_6\) has a larger molecular structure with more electrons. Larger, more complex molecules have larger, more polarizable electron clouds. This leads to stronger London - dispersion forces, which cause greater deviation from ideal gas behavior. \(C_2H_6\) has a larger, more polarizable electron cloud than \(CH_4\), making option B correct.
3. Average kinetic energy: At the same temperature, equimolar samples of different gases have the same average kinetic energy (\(K_{avg}=\frac{3}{2}RT\)), so option C is incorrect.
4. Average speed: The average speed of gas molecules is related to molar mass (\(u = \sqrt{\frac{3RT}{M}}\)). Since \(C_2H_6\) has a higher molar mass than \(CH_4\), at the same temperature, \(C_2H_6\) has a lower average speed, so option D is incorrect.

Answer:

B. \(C_2H_6\) molecules have a larger, more polarizable electron cloud than \(CH_4\) molecules do.