If the following rate constant, Kf, and the reverse rate constant, Kr, for a che
ID: 504770 • Letter: I
Question
If the following rate constant, Kf, and the reverse rate constant, Kr, for a chemical reaction are NOT equal, which must be true.
a: The reaction will be unable to acheive equilibrium
b: Kf and Kr will become equal as equilibrium is approached owing to concentration changes.
c: Kf and Kr will become equal as equilibrium is approached owing to temperature changes
d: Kf and Kr will remain unequal bot rates will become equal owing to concentration changes
e: Kf and Kr will remain unequal but the rates will become equal owing to temperature changes
Explanation / Answer
Answer:
Equilibrium constant (K) for any reaction is the ratio of Rate constant for Forward reaction (Kf) to the Rate constant for Backward reaction (Kr).
K = Kf / Kr.
The reaction said to be at equilibrium when Rate of forward reaction Rf become equal to Rate of backward reaction (Rr) i.e Rf = Rr. (not when Kf = Kr i.e when rate constants equals which is not goining to happen)
Hence we have following inferences,
a) FALSE. Reaction will be able to achieve equilibrium.(As per Le Chatelier's Principle)
b) FALSE. Kf and Kr may or may not become equal as equilibrium is approached owing to concentration changes.
c) & e) FALSE. Temperature affects Rates of reaction (forward or Backward) and not the rate constants.
d) TRUE. Kf and Kr remains unequal but respective rate will become equal owing to concentration change.
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