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What is the hydronium ion concentration of a solution with a pOH of 6.90?

A. [tex]$6.29 \times 10^{-7} M$[/tex]
B. [tex]$6.53 \times 10^{-7} M$[/tex]
C. [tex]$7.18 \times 10^{-8} M$[/tex]
D. [tex]$7.94 \times 10^{-8} M$[/tex]


Sagot :

To find the hydronium ion concentration \([H_3O^+]\) of a solution with a given \( \text{pOH} \) of 6.90, we follow these steps:

1. Calculate the pH:
The relationship between pH and pOH is given by:
[tex]\[ \text{pH} + \text{pOH} = 14 \][/tex]
So, we can find the pH by subtracting the pOH from 14:
[tex]\[ \text{pH} = 14 - \text{pOH} = 14 - 6.90 = 7.10 \][/tex]

2. Calculate the hydronium ion concentration \([H_3O^+]\):
The hydronium ion concentration can be found using the formula:
[tex]\[ [H_3O^+] = 10^{-\text{pH}} \][/tex]
Plugging in the pH value:
[tex]\[ [H_3O^+] = 10^{-7.10} \approx 7.94 \times 10^{-8} \, M \][/tex]

3. Compare calculated \([H_3O^+]\) with given choices:
We are given the following options:
[tex]\[ \begin{align*} &6.29 \times 10^{-7} \, M \\ &6.53 \times 10^{-7} \, M \\ &7.18 \times 10^{-8} \, M \\ &7.94 \times 10^{-8} \, M \\ \end{align*} \][/tex]
The calculated \( [H_3O^+] \) value is \( \approx 7.94 \times 10^{-8} \, M \), which matches most closely with the option \( 7.94 \times 10^{-8} \, M \).

Therefore, the hydronium ion concentration is [tex]\( 7.94 \times 10^{-8} \, M \)[/tex], which matches the fourth option.