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What Is the Ph of a 3.5x10-11 M H+ Solution

Assignment 026

Question 1
What is the pH of a solution where [H3O +] = 5.2x10-2?

Question 2
What is the pH of a solution where [OH-] = 3.4x10-12?

Question 3
What is the pOH of a solution where [OH-] = 5.9x10-8?

Question 4
What is the [H3O +] in a solution with a pH of 9.45?

Question 5
What is the [ OH- ] in a solution with a pH of 6.88?

Question 6
What is the [ OH- ] in a solution where [H3O +] is 5.37x10-9?

Question 7
What is the [H3O +] in a solution where [ OH- ] is 7.75x10-7?

ANSWERS

Question 1 (00000001B0402400, Variation No. 70): 1.28

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An alternative method of specifying the acidity of a solution is by using the term called pH (for the "power of the hydrogen ion")

pH = - log10 [H+] = - log10 [H3O +]

The lower the pH, the more acidic the solution.

In this problem,

pH = - log10 [H3O +] = - log10 [5.2x10-2] = 1.28

Question 2 (00000001B0402401, Variation No. 53): 2.53

Feedback
An alternative method of specifying the acidity of a solution is by using the term called pH (for the "power of the hydrogen ion")

pH = - log10 [H+] = - log10 [H3O +]

The lower the pH, the more acidic the solution.

In this problem, we are given the [

OH-

] not the [H3O + ] ; therefore, there are several ways to obtain the correct answer. The easiest method is to combine the following two equations into one simple equation:

14.00 = pH + pOH
pOH = - log10 [OH-]

rearranging the first equation for pH and substituting the second equation for pOH in the first we obtain

pH = 14.00 + log[OH-] = 14.00 + log[3.4x10-12] = 2.53

Note: This is a useful equation to remember that converts [OH-] to pH quite easily.

Question 3 (00000001B0402402, Variation No. 57): 7.23

Feedback
An alternative method of specifying the acidity of a solution is by using the term called pH (for the "power of the hydrogen ion")

pH = - log10 [H+] = - log10 [H3O +]

A similar approach is used for the hydroxide ion concentration. The pOH of a solution is defined as

pOH = - log10 [

OH-

]

In this problem,

pOH = - log10 [

OH-

] = - log10 [5.9x10-8] = 7.23

Question 4 (00000001B0402403, Variation No. 28): 3.5x10-10 M

Feedback
An alternative method of specifying the acidity of a solution is by using the term called pH (for the "power of the hydrogen ion")

pH = - log10 [H+] = - log10 [H3O +]

[H3O +] = [H+] = 10-pH

In this problem,

[H3O +] = 10-9.45 = 3.5x10-10 M

Question 5 (00000001B0402404, Variation No. 30): 7.6x10-8 M

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In this problem we are given the pH but want the [

OH-

]. To obtain this value, we will need to convert the pH to pOH by rearranging the following equation

14.00 = pH + pOH
pOH = 14.00 - pH = 14.00 - 6.88 = 7.12

Next, we will calculate the [

OH-

] using the following equation

[

OH-

] = 10-pOH = 10-7.12 = 7.6x10-8 M

Question 6 (00000001B0402405, Variation No. 77): 1.86x10-6 M

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There is an inverse relationship between [

OH-

] and [H3O +] through the ionization of water. The equilibrium constant expression is

Kw = [H3O + ][

OH-

] = 1.00 x 10-14 @25oC

where Kw is referred to as the ionization constant for water. Plugging in the given concentration for hydronium and rearranging for the concentration of hydroxide we obtain

[

OH-

] = 1.00 x 10-14 / 5.37x10-9 = 1.86x10-6 M

Question 7 (00000001B0402406, Variation No. 1): 1.29x10-8 M

Feedback
There is an inverse relationship between [

OH-

] and [H3O +] through the ionization of water. The equilibrium constant expression is

Kw = [H3O + ][

OH-

] = 1.00 x 10-14 @25oC

where Kw is referred to as the ionization constant for water. Plugging in the given concentration for hydroxide and rearranging for the concentration of hydronium we obtain

[H3O +]= 1.00 x 10-14 / 7.75x10-7 = 1.29x10-8 M

What Is the Ph of a 3.5x10-11 M H+ Solution

Source: http://www.faculty.sfasu.edu/janusama/Assignment026.htm