Question

Which solution will be basic ? A) [H3O+] = 10^-5M B) [H3O+] =10^-12M C) [H3O+] =10^-7M D) [H3O+] =10^-4M

Page 150 Chapter - 7.Acids, Bases and Salts

Answer 1

Answer:

Option (B) $[H_3O^{+}]=10^{-12}M$

Explanation:

$H_2O+H^{+}\rightarrow H_3O^{+}$

Therefore the concentration of $H_3O^{+}$ is nothing but the concentration of $H^{+}$ ions

Also the pH is given by

$\boxed{pH=-\log[H^+]}$

Therefore the pH value of the given concentration of $H_3O^{+}$ are as following

(A) When $[H_3O^{+}] =10^{-5}M$

$pH=-\log[10^{-5}]=-(-5\log10)=5$

(B) When $[H_3O^{+}] =10^{-12}M$

$pH=-\log[10^{-12}]=-(-12\log10)=12$

(C) When $[H_3O^{+}] =10^{-7}M$

$pH=-\log[10^{-7}]=-(-7\log10)=7$

(D) When $[H_3O^{+}] =10^{-4}M$

$pH=-\log[10^{-4}]=-(-4\log10)=4$

The solution with pH value greater than 7 will be basic

Here the solution with concentration of $H_3O^{+}$ being $10^{-12}M$ has the highest pH

Therefore it is basic