Consider this reaction: →2NH3g+N2g3H2g At a certain temperature it obeys this rate law: rate =2.11·M−1s−1NH32 Suppose a vessel contains NH3 at a concentration of 0.590M. Calculate how long it takes for the concentration of NH3 to decrease by 88.0%. You may assume no other reaction is important. Round your answer to 2 significant digits

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Answer:

5.9 s

Explanation:

Let's consider the following reaction.

2 NH₃(g) ⇄ N₂(g) + 3 H₂(g)

The rate law is:

rate = 2.11 M⁻¹s⁻¹[NH₃]²

where

2.11 M⁻¹s⁻¹ is the rate constant (k)

2 is the order of reaction for NH₃

The initial concentration of NH₃ ([NH₃]₀) is 0.590 M. If it decreases by 88.0%, the final concentration ([NH₃]) will be 100.0% - 88.0% = 12.0% of the initial concentration, that is, 0.0708 M.

For a second order reaction we can use the following expression.

[tex]\frac{1}{[NH_{3}]} =\frac{1}{[NH_{3}]_{0}} + k.t\\\frac{1}{0.0708M} =\frac{1}{0.590M} +2.11M^{-1} s^{-1} .t\\t=5.89s[/tex]

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