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33. Calculate the concentration of hydronium, [tex]H_3O^+[/tex], in a solution with:

a. [tex]\([ OH^- ]=5 \times 10^{-5} M\)[/tex]

b. [tex]\([ OH^- ]=100[ H_3O^+]\)[/tex]

c. [tex]\(0.05 M Sr(OH)_2\)[/tex]

d. [tex]\(0.01 M H_2SO_4\)[/tex]


Sagot :

Certainly! Let's go through each part of the question step-by-step to find the concentration of hydronium ions, [tex]\( \text{H}_3\text{O}^+ \)[/tex], in different scenarios.

### Part a: Given [tex]\([ \text{OH}^- ] = 5 \times 10^{-5} \text{ M}\)[/tex]

We use the ion-product constant for water at 25 degrees Celsius:
[tex]\[ K_w = [\text{H}_3\text{O}^+][\text{OH}^-] = 1 \times 10^{-14} \][/tex]

We can find the concentration of [tex]\(\text{H}_3\text{O}^+\)[/tex] using the given [tex]\([ \text{OH}^- ]\)[/tex]:
[tex]\[ [\text{H}_3\text{O}^+] = \frac{K_w}{[ \text{OH}^- ]} \][/tex]

Substitute the values:
[tex]\[ [\text{H}_3\text{O}^+] = \frac{1 \times 10^{-14}}{5 \times 10^{-5}} \][/tex]
[tex]\[ [\text{H}_3\text{O}^+] = 2 \times 10^{-10} \text{ M} \][/tex]

So, the concentration of hydronium ions is [tex]\( 2 \times 10^{-10} \text{ M} \)[/tex].

### Part c: Given [tex]\(0.05 \text{ M Sr(OH)}_2\)[/tex]

Strontium hydroxide, [tex]\( \text{Sr(OH)}_2 \)[/tex], dissociates completely in water and provides 2 hydroxide ions ([tex]\( \text{OH}^- \)[/tex]) per formula unit:
[tex]\[ \text{Sr(OH)}_2 \rightarrow \text{Sr}^{2+} + 2\text{OH}^- \][/tex]

Therefore, the concentration of hydroxide ions is:
[tex]\[ [ \text{OH}^- ] = 2 \times 0.05 \text{ M} = 0.10 \text{ M} \][/tex]

Now, we use the ion-product constant for water:
[tex]\[ [\text{H}_3\text{O}^+] = \frac{K_w}{[ \text{OH}^- ]} \][/tex]

Substitute the values:
[tex]\[ [\text{H}_3\text{O}^+] = \frac{1 \times 10^{-14}}{0.10} \][/tex]
[tex]\[ [\text{H}_3\text{O}^+] = 1 \times 10^{-13} \text{ M} \][/tex]

So, the concentration of hydronium ions is [tex]\( 1 \times 10^{-13} \text{ M} \)[/tex].

### Part b: Given [tex]\([ \text{OH}^- ] = 100 [ \text{H}_3\text{O}^+ ]\)[/tex]

This gives us a relationship between [tex]\([ \text{OH}^- ]\)[/tex] and [tex]\([ \text{H}_3\text{O}^+ ]\)[/tex]:

[tex]\[ [ \text{OH}^- ] = 100 [ \text{H}_3\text{O}^+ ] \][/tex]

We use the ion-product constant for water:
[tex]\[ K_w = [\text{H}_3\text{O}^+][\text{OH}^-] \][/tex]

Using the given relationship:
[tex]\[ K_w = [\text{H}_3\text{O}^+] \cdot 100 [ \text{H}_3\text{O}^+ ] \][/tex]
[tex]\[ K_w = 100 [\text{H}_3\text{O}^+]^2 \][/tex]

Solving for [tex]\([ \text{H}_3\text{O}^+] \)[/tex]:
[tex]\[ [\text{H}_3\text{O}^+]^2 = \frac{K_w}{100} \][/tex]
[tex]\[ [\text{H}_3\text{O}^+] = \sqrt{\frac{1 \times 10^{-14}}{100}} = \sqrt{1 \times 10^{-16}} \][/tex]
[tex]\[ [\text{H}_3\text{O}^+] = 1 \times 10^{-8} \text{ M} \][/tex]

So, the concentration of hydronium ions is [tex]\( 1 \times 10^{-8} \text{ M} \)[/tex].

### Part d: Given [tex]\(0.01 \text{ M H}_2\text{SO}_4\)[/tex]

Sulfuric acid, [tex]\( \text{H}_2\text{SO}_4 \)[/tex], is a strong acid that dissociates completely in water and provides 2 hydronium ions ([tex]\( \text{H}_3\text{O}^+ \)[/tex]) per formula unit:
[tex]\[ \text{H}_2\text{SO}_4 \rightarrow 2\text{H}_3\text{O}^+ + \text{SO}_4^{2-} \][/tex]

Therefore, the concentration of hydronium ions is:
[tex]\[ [\text{H}_3\text{O}^+] = 2 \times 0.01 \text{ M} = 0.02 \text{ M} \][/tex]

So, the concentration of hydronium ions is [tex]\( 0.02 \text{ M} \)[/tex].

### Summary:
a. [tex]\( [\text{H}_3\text{O}^+] = 2 \times 10^{-10} \text{ M} \)[/tex]

c. [tex]\( [\text{H}_3\text{O}^+] = 1 \times 10^{-13} \text{ M} \)[/tex]

b. [tex]\( [\text{H}_3\text{O}^+] = 1 \times 10^{-8} \text{ M} \)[/tex]

d. [tex]\( [\text{H}_3\text{O}^+] = 0.02 \text{ M} \)[/tex]