PH is a logarithmic scale used to indicate the hydrogen ion concentration, [H+], of a solution: pH=−log[H+] Due to the autoionization of water, in any aqueous solution, the hydrogen ion concentration and the hydroxide ion concentration, [OH−], are related to each other by the Kw of water: Kw=[H+][OH−]=1.00×10−14 where 1.00×10−14 is the value at approximately 297 K. Based on this relation, the pH and pOH are also related to each other as 14.00=pH+pOH.
The temperature for each solution is carried out at approximately 297 K where Kw=1.00×10−14.

a. 0.40 g of hydrogen chloride (HCl) is dissolved in water to make 4.5 L of solution. What is the pH of the resulting hydrochloric acid solution?
b. 0.80 g of sodium hydroxide (NaOH) pellets are dissolved in water to make 2.0 L of solution. What is the pH of this solution?