Two Students Measured an Equilibrium Constant for the Same Chemical

question 98

Multiple Choice

Two students measured an equilibrium constant for the same chemical reaction. Ken obtained a value of 130 for the equilibrium constant, but Barbie obtained a value of 11.4. The instructor checked their results and said they were both correct. How can that be?

• A) The values vary according to the way the measurement is made. Ken must have measured product concentrations, while Barbie measured reactant concentrations.
• B) The values vary according to the starting conditions of the reaction prior to equilibrium. Ken must have started with all reactants, while Barbie must have started with all products.
• C) The values vary according to the stoichiometric coefficients that are used. The balancing coefficients that Ken used must have been twice those that Barbie used.
• D) The values vary according to direction of the reaction. Ken must have used the reverse reaction.
• E) The instructor must have made a mistake as the equilibrium constant for a reaction must always be the same.

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