A sample of `HI(g)` is placed in flask at at pressure of `0.2` atm . At equilibrium the partial pressure of `HI(g)` is `0.04 `atm what is `K_(p)` for the given equilibrium ?
`2HI(g) hArr H_(2)(g) + I_(2)(g)`

Explanation

`2HI(g) hArr H_(2)(g)+I_(2)(g)`
`{:("Initial pressure",0.2 atm,,0,0),("At Eq",0.04 atm,,0.16/2 atm,0.16/2 atm),(,,,=0.08 atm,=0.08 atm):}`
`("Decrease in the pressure of" HI=0.2-0.04=0.16 atm)`
`:. K_(p)=(p_(H_(2))xxp_(I_(2)))/(P_(HI)^(2))=(0.08 atmxx0.08 atm)/((0.04 atm)^(2))=4.0`