Consider the gaseous equilibrium
H2(g) + I2(g) ⇌ 2 HI(g)
A particulate diagram produced by a lab partner shows the following:
• 20 purple diatomic molecules labeled “H2”
• 20 red diatomic molecules labeled “I2”
• 40 purple–red heteronuclear molecules labeled “HI”
Closer inspection reveals that the purple diatomic molecules actually contain iodine atoms, and the red diatomic molecules actually contain hydrogen atoms—the labels are reversed.
a. Identify the labeling error in the diagram and explain why it would mislead someone analyzing the equilibrium mixture.
b. Describe how the mislabeled diagram could lead to an incorrect numerical value for the equilibrium constant when the particle counts are used in the equilibrium expression.
c. Propose two best-practice guidelines students should follow to avoid such representational errors when constructing particulate diagrams for equilibrium systems.