Under certain conditions the rate of this reaction is zero order in ammonia with a rate constant of ·0.0038Ms−1: 2NH3(g)→N2(g)+3H2(g) Suppose a 450.mL flask is charged under these conditions with 150.mmol of ammonia. How much is left 20.s later? You may assume no other reaction is important. Be sure your answer has a unit symbol, if necessary, and round it to 2 significant digits.

mmol of is left after 20 s.

Explanation:

Initial concentration of = M = 0.333 M

The integrated rate law for the given zero order reaction:

where, represents concentration of after "t" time, k is rate constant and is initial concentration of .

Here, k = 0.0038 M/s, = 0.333 M and t = 20 s

So,

   or, = 0.257 M

So, number of mol of left after 20 s = mol = 0.11565 mol

So, number of mmol of left after 20 s = 115.65 mmol = mmol (2 sig. digits)