For the reaction W(aq) + 2X(aq) ⇋ 2Y(aq) + 3Z(aq) What are the correct units for the equilibrium constant Kc?
Correct answer: B. mol2 dm-6
- A. mol dm-3
- B. mol2 dm-6
- C. mol-1 dm3
- D. mol-2 dm6
Explanation
The equilibrium constant Kc is calculated using the formula Kc = [Y]2[Z]3 / [W][X]2. For the given reaction, the total moles of products (5 moles) minus the total moles of reactants (3 moles) results in a net change of 2 moles. Thus, the units for Kc are (mol dm-3)2 (mol dm-3)3 / (mol dm-3)(mol dm-3)2, simplifying to mol2 dm-6. This confirms that Option B is correct. The other options incorrectly calculate the change in moles, leading to incorrect Kc units.
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Reversible reactions reach dynamic equilibrium when forward and reverse rates become equal, and Le Chatelier's principle predicts the effect of changing concentration, pressure or temperature. The chapter also covers solubility product, the common ion effect, buffer action and the conditions used in Haber's process, with equilibrium shifts distinguished from changes in the equilibrium constant.
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