The generic reaction
2A?B
has the following rate laws:
forward reaction:reversereaction:rate=kf[A]2rate=kr[B]
where kf is the rate constant for the forward reactionand kr is the rate constant for the reverse reaction. Atequilibrium, the two rates are equal and sokf[A]2=kr[B]. The equilibrium constant for areaction is related by the law of mass action to the rate constantsfor the forward and reverse reactions:
Kc=[B][A]2=kfkr
Formation of nitrosyl bromide
Nitrosyl bromide, NOBr, is formed in the reaction of nitricoxide, NO, with bromine, Br2:
2NO(g)+Br2(g)?2NOBr(g)
The reaction rapidly establishes equilibrium when the reactantsare mixed.
A.
At a certain temperature the concentration of NO was 0.400M and that of Br2 was 0.265M . At equilibrium theconcentration of NOBr was found to be 0.250 M. What is thevalue of Kc at this temperature?
Express your answer numerically.
