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.

C HI = 0.1 M 0.210 second later

Explanation:

∴ 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

"the periodic table is arranged in order of atomic number."