In a study of the decomposition of ammonia on a tungsten surface at 1100 degree

Question

In a study of the decomposition of ammonia on a tungsten surface at 1100 degree C NH_3 rightarrow 1/2 N_2 + 3/2 H_2 the following data were obtained: The observed half life for this reaction when the starting concentration is 8.55 times 10^-3 M is s and when the starting concentration is 4.28 times 10^-2 M is s. The average rate of disappearance of NH_3 from t = 0 s to t = 441 s is M s^-1. The average rate of disappearance of NH_3 from t = 441 s to t = 662 s is M s^-1. Based on these data, the rate constant for this order reaction is M s^-1.

Explanation / Answer

1) when [8.55 x 10-3 M] then half life = 441 seconds

when [4.28 x 10-3M] then half life = 221 seconds

2) rate of disappearence of NH3 when t = 0 to 441 seconds = (8.55 x 10-3  - 4.28 x 10-3) / 441 = 9.7 x 10-6 M/s

3) t = 441 to 662 seconds then = (4.28 x 10-3  - 2.14 x 10-3) / 221 = 9.7 x 10-6 M/s

4) when concentration decreases half life also decreases so reaction is zero order

order = zero

K = [A0] /2t1/2

K = [0.00855 ] / 2x441

K = 0.00855 / 882

K = 9.7 x 10-6 Ms-1

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.