Question

At a certain temperature the rate of this reaction is first order in HI with a rate constant of :7.21s-1

2HI(g) â H2(g) + I2(g)

Suppose a vessel contains HI at a concentration of 0.440M
Calculate the concentration of HI in the vessel 0.210 seconds later. You may assume no other reaction is important. Round your answer to 2 significant digits.

Answer 1

C HI = 0.1 M ..... 0.210 second later

Step-by-step explanation:

• 2 HI(g) = H2(g) + I2(g)

∴ order (∝) = 1

∴ κ = 7.21 s-1

∴ Cao = 0.440 M ...... initial concentration of HI

∴ t = 0.210 s

rate of this reaction (r):

⇒ - ra = κ.(Ca)∧∝ .......∝ = 1

⇒ - ra = κ.Ca = - δCa/δt

⇒ - δCa/Ca = κ.δt

⇒ - ∫ δCa/Ca = κ ∫δt

⇒ Ln Cao/Ca = κ.t

⇒ Cao/Ca = e∧(κ.t)

⇒ Ca = Cao/e∧(κ.t)

⇒ Ca = ( 0.44 ) / e∧(7.21×0,21)

⇒ Ca = 0.0968 M

⇒ Ca = 0.1 M