Question

Calculate the pH and pOH of the solutions with the following hydrogen ion or hydroxide ion concentrations. Indicate which solutions are acidic, basic, or neutral. (And please show how to solve! Thanks!) a. [H+]= 3.45x10^-8 M b. [H+]= 2.0x10^-5 M c. [H+]= 7.0x10^-8 M d. [OH-]= 8.56x10^-4 M

Answer 1

Answer :

(a) The pH of the solution is, 7.46 and solution is basic in nature.

(b) The pH of the solution is, 4.70 and solution is acidic in nature.

(c) The pH of the solution is, 7.15 and solution is basic in nature.

(d) The pH of the solution is, 10.9 and solution is basic in nature.

Explanation :

pH : It is defined as the negative logarithm of hydrogen ion concentration.

The pH range is, 1 to 14.

When the pH = 7 then the solution is neutral.

When the pH > 7 then the solution is basic.

When the pH < 7 then the solution is acidic.

Part (a) :  [H⁺]= 3.45 × 10⁻⁸ M

Now we have to calculate the pH of the solution.

$pH=-\log [H^+]$

$pH=-\log (3.45\times 10^{-8})$

$pH=7.46$

The pH of the solution is 7.46 that means the solution is basic in nature.

Part (b) :  [H⁺]= 2.0 × 10⁻⁵ M

Now we have to calculate the pH of the solution.

$pH=-\log [H^+]$

$pH=-\log (2.0\times 10^{-5})$

$pH=4.70$

The pH of the solution is 4.70 that means the solution is acidic in nature.

Part (c) :  [H⁺]= 7.0 × 10⁻⁸ M

Now we have to calculate the pH of the solution.

$pH=-\log [H^+]$

$pH=-\log (7.0\times 10^{-8})$

$pH=7.15$

The pH of the solution is 7.15 that means the solution is basic in nature.

Part (d) :  [OH⁻]= 8.56 × 10⁻⁴ M

Now we have to calculate the pOH of the solution.

$pOH=-\log [OH^-]$

$pOH=-\log (8.56\times 10^{-4})$

$pOH=3.07$

Now we have to calculate the pH.

$pH+pOH=14\\\\pH=14-pOH\\\\pH=14-3.07\\\\pH=10.9$

The pH of the solution is 10.9 that means the solution is basic in nature.