Answer: [tex]k_a[/tex] for [tex]C_6H_5NH_3^+[/tex] at 25°C is [tex]0.588\times 10^{-4}[/tex]
Explanation: We are given [tex]k_b[/tex] of [tex]C_6H_5NH_2[/tex] at 25°C which is [tex]1.7\times 10^{-9}[/tex]
To calculate the [tex]k_a[/tex] of [tex]C_6H_5NH_3^+[/tex], we use the formula:
[tex]k_w=k_a\times k_b[/tex]
[tex]k_w\text{ at }25^o=1\times 10^{-14}[/tex]
Putting values in above equation, we get:
[tex]1\times 10^{-14}=k_a\times (1.7\times 10^{-9})\\k_a=0.588\times 10^{-5}[/tex]