The pH of a solution is 2.57 at 25 degrees C. What is the molar concentration of hydronium ions? What is the molar concentration of hydroxide ions?

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The pH of a solution is 2.57 at 25 degrees C. What is the molar concentration of hydronium ions? What is the molar concentration of hydroxide ions?

The pH of a solution is 2.57 at 25 degrees C.

What is the molar concentration of hydronium ions?
What is the molar concentration of hydroxide ions?

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Answer 1 · 2016-09-07T07:47:03

Given the definition of $pH$ , I can write immediately that if $pH=2.57$ , then $[H_3O^+]=10^(-2.57)$ $mol*L^-1$

Explanation:

And also given the definitions, I know that $[H_3O^+][HO^-]=10^-14$ under standard condtions; taking $log_10$ of both sides, this gives our defining relationship:

$pH+pOH=14$

And thus $pOH$ $=$ ${14-2.57}$ , and $HO^-$ $=$ $10^(-11.43)*mol*L^-1$ .

Of course you will need a calculator to assess these values. I have never got one handy.

In a neutral solution at $298*K$ , the equilibrium operates, $[H_3O^+][HO^-]=10^-14$ , and $pH$ $=$ $pOH$ $=$ $7$ . At temperatures higher than $298K$ , how would you expect $pH$ to evolve in a neutral solution. Would it increase, decrease, stay the same?

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The pH of a solution is 2.57 at 25 degrees C. What is the molar concentration of hydronium ions? What is the molar concentration of hydroxide ions?