The hydrogen ion concentration in weak acid of dissociation constant `K_(a)` and concentration `c` is nearly equal to

Options

A. `sqrt(K_(a)//c)`
B. `c//K_(a)`
C. `K_(a)c`
D. `sqrt(K_(a)c)`

Answer

D

Explanation

`{:(HA,rarr,H^(+),+,A^(-)),(C(1-alpha),,C alpha,,C alpha):}`
Hydrogen ion concentration `[H^(+)] = C alpha` ....(i)
By the ostwald's law `alpha = sqrt((K_(a))/(C))` ...(ii)
By putting this value in equation (i) we get
`rArr c xx sqrt((K_(a))/(C)) = sqrt(K_(a)C)`.