Calculating pH and pOH - AP Chemistry
Card 0 of 64
There are __________ hydrogen ions in a solution with a pH of 3 than in a solution with a pH of 6.
There are __________ hydrogen ions in a solution with a pH of 3 than in a solution with a pH of 6.
Each whole number on the pH scale represents a factor of ten difference in concentration of hydrogen ions. We con verify this by finding the hydrogen ion concentrations for the two given pH values.
If we take the ratio of these values, we can see that there is a difference of 1000-times more protons in the solution with a pH of 3.
Each whole number on the pH scale represents a factor of ten difference in concentration of hydrogen ions. We con verify this by finding the hydrogen ion concentrations for the two given pH values.
If we take the ratio of these values, we can see that there is a difference of 1000-times more protons in the solution with a pH of 3.
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A sample of gastric juice has a pH of 2.5. What is the hydrogen ion concentration in this secretion?
A sample of gastric juice has a pH of 2.5. What is the hydrogen ion concentration in this secretion?
The concentration of hydrogen ions must lie somewhere between 
and 
; alternatively stated, it is between 
and 
. The pH of a solution with hydrogen ion concentration of 
will be 3, and the pH of a solution with hydrogen ion concentration 
will be 2; thus, our concentration must lie between these two values, since our pH is 2.5
To find the exact concentration, you must be familiar with the logarithmic scale. A difference of 0.5 is equivalent to a log of 3.
Our answer must therefore be 
, or 
.
We can calculate the pH in reverse to check our answer.
The concentration of hydrogen ions must lie somewhere between
To find the exact concentration, you must be familiar with the logarithmic scale. A difference of 0.5 is equivalent to a log of 3.
Our answer must therefore be
We can calculate the pH in reverse to check our answer.
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Sodium hydroxide is a strong base. What is the pH of a 0.02M sodium hydroxide solution?
Sodium hydroxide is a strong base. What is the pH of a 0.02M sodium hydroxide solution?
Since sodium hydroxide is a strong base, it will dissociate completely in water. This means that the concentration of the base will be equal to the concentration of hydroxide ions after the reaction runs to completion.
We can find the concentration of hydroxide ions via stoichiometry. One hydroxide ion is created from each molecule of sodium hydroxide that dissociates.
Since we have the concentration of hydroxide ions, we can solve for the pOH of the solution.
The question asks us to find the pH of the solution, so we will need to convert pOH to pH. To do so, we simply subtract the pOH from 14.
The pH of the solution is 12.3. Because sodium hydroxide is a strong base, it makes sense that the pH is above 7.
Since sodium hydroxide is a strong base, it will dissociate completely in water. This means that the concentration of the base will be equal to the concentration of hydroxide ions after the reaction runs to completion.
We can find the concentration of hydroxide ions via stoichiometry. One hydroxide ion is created from each molecule of sodium hydroxide that dissociates.
Since we have the concentration of hydroxide ions, we can solve for the pOH of the solution.
The question asks us to find the pH of the solution, so we will need to convert pOH to pH. To do so, we simply subtract the pOH from 14.
The pH of the solution is 12.3. Because sodium hydroxide is a strong base, it makes sense that the pH is above 7.
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Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
The pH of a solution of 
is lowered from 4 to 3, and then from 3 to 2. Which of the following is the most accurate description of what happens during these transitions?
Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
The pH of a solution of
The pH scale is logarithmic. Every pH unit drop corresponds to a tenfold increase in protons.
The pH scale is logarithmic. Every pH unit drop corresponds to a tenfold increase in protons.
Compare your answer with the correct one above
Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
A scientist is studying an aqueous sample of 
, and finds that the hydroxide concentration is 
. Which of the following is true?
Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
A scientist is studying an aqueous sample of
Given the hydroxide ion concentration, we will need to work using pOH to find the pH. We know that the sum of pH and pOH is equal to 14.
Use our value for the concentration to find the pOH.
Now that we have the pOH, we can use it to solve for the pH.
Given the hydroxide ion concentration, we will need to work using pOH to find the pH. We know that the sum of pH and pOH is equal to 14.
Use our value for the concentration to find the pOH.
Now that we have the pOH, we can use it to solve for the pH.
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What is the pOH of a 
aqueous solution of 
?
What is the pOH of a
The first step for this problem is to find the pH. We can then derive the pOH from the pH value.
The pH is given by the equation 
. Since hydrochloric acid is monoprotic, the concentration of the solution is equal to the concentration of protons.
Using this value and the pH equation, we can calculate the pH.
Now we can find the pOH. The sum of the pH and the pOH is always 14.
The pOH of the solution is 7.8.
Alternatively, a shortcut can be used to estimate the pH. If 
is in the form 
, then pH is roughly 
.
For this question, this shortcut gets us a pH of 6.4, which produces a pOH of 7.6; very close to the real answer!
The first step for this problem is to find the pH. We can then derive the pOH from the pH value.
The pH is given by the equation
Using this value and the pH equation, we can calculate the pH.
Now we can find the pOH. The sum of the pH and the pOH is always 14.
The pOH of the solution is 7.8.
Alternatively, a shortcut can be used to estimate the pH. If
For this question, this shortcut gets us a pH of 6.4, which produces a pOH of 7.6; very close to the real answer!
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An arterial blood sample from a patient has a pH of 7.4. One day later, the same patient has an arterial blood pH of 7.15. How many times more acidic is the patient's blood on the second day?
An arterial blood sample from a patient has a pH of 7.4. One day later, the same patient has an arterial blood pH of 7.15. How many times more acidic is the patient's blood on the second day?
The equation to calculate pH is:
The normal pH of arterial blood is around 7.4. This reflects a concentration of hydrogen ions that can be found using the pH equation.
Using similar calculations for the second blood sample, we can find the hydrogen ion concentration again.
Now that we have both concentrations, can find the ratio of the acidity of the two samples.
You may know from biological sciences that this is approaching a lethal level of acidosis.
The equation to calculate pH is:
The normal pH of arterial blood is around 7.4. This reflects a concentration of hydrogen ions that can be found using the pH equation.
Using similar calculations for the second blood sample, we can find the hydrogen ion concentration again.
Now that we have both concentrations, can find the ratio of the acidity of the two samples.
You may know from biological sciences that this is approaching a lethal level of acidosis.
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You are presented with a solution that has a pOH of 2.13. What is the pH of this solution?
You are presented with a solution that has a pOH of 2.13. What is the pH of this solution?
pH and pOH are the log concentrations of protons and hydroxide ions, respectively.
The sum of pH and pOH is always 14. This is because the product of proton concentration and hydroxide concentration must always equal the equilibrium constant for the ionization of water, which is equal to 
.
In this question, we know that the pOH is equal to 2.13, allowing us to solve for the pH.
pH and pOH are the log concentrations of protons and hydroxide ions, respectively.
The sum of pH and pOH is always 14. This is because the product of proton concentration and hydroxide concentration must always equal the equilibrium constant for the ionization of water, which is equal to
In this question, we know that the pOH is equal to 2.13, allowing us to solve for the pH.
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What is the pH for a 0.05M solution of hydrochloric acid?
What is the pH for a 0.05M solution of hydrochloric acid?
Hydrochloric acid is a strong monoprotic acid, meaning that it will dissociate completely in solution and generate one proton from each acid molecule. This means that a 0.05M solution of hydrochloric acid will result in a 0.05M concentration of protons.
The equation for pH is as follows:
Hydrochloric acid is a strong monoprotic acid, meaning that it will dissociate completely in solution and generate one proton from each acid molecule. This means that a 0.05M solution of hydrochloric acid will result in a 0.05M concentration of protons.
The equation for pH is as follows:
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Hydrofluoric acid has a 
value of 
. What is the pH of a 
solution of hydrofluoric acid?
Hydrofluoric acid has a
Hydrofluoric acid is a weak acid, meaning that we will need to use an ICE table in order to find the pH of the solution.
The balanced reaction for hydrofluoric acid in water is:
I: Before the reaction proceeds, we have 0.04M of hydrofluoric acid. Since water is a liquid, its concentration is irrelevant for the equilibrium expression. There are also no products yet made.
C: Once the reaction reaches equilibrium, both the hydronium and fluoride concentrations will have increased by an unknown concentration. We will call this increase 
. Conversely, the concentration of hydrofluoric acid concentration will have decreased by the same amount, in this case 
.
E: Using the equilibrium expression and making it equal to the acid dissociation constant, we can solve for 
.
Note: Since the value for 
is going to be very small compared to the initial acid concentration, we can disregard the 
in the denominator:
Keep in mind that 
is equal to the concentration of hydronium ions now in the solution.
Use this value in the equation for pH:
Hydrofluoric acid is a weak acid, meaning that we will need to use an ICE table in order to find the pH of the solution.
The balanced reaction for hydrofluoric acid in water is:
I: Before the reaction proceeds, we have 0.04M of hydrofluoric acid. Since water is a liquid, its concentration is irrelevant for the equilibrium expression. There are also no products yet made.
C: Once the reaction reaches equilibrium, both the hydronium and fluoride concentrations will have increased by an unknown concentration. We will call this increase
E: Using the equilibrium expression and making it equal to the acid dissociation constant, we can solve for
Note: Since the value for
Keep in mind that
Use this value in the equation for pH:
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What is the pH of a 
ammonia solution if its 
value is 
?
What is the pH of a
Ammonia is a weak base, meaning that we will require an ICE table in order to determine the pH of the solution.
Let's look at the dissociation of ammonia:
I: Before the reaction proceeds, ammonia has a concentration of 0.02M. No product has yet been made.
C: When the reaction is at equilibrium, the products will increase by a concentration of 
. Conversely, ammonia's concentration will decrease by the same amount, 
.
E: By setting the equilibrium expression equal to the base dissociation constant, we can solve for the value of 
.
Note: because the value for 
will be so much less than the initial base concentration, we can omit it from the denominator:
Keep in mind that is equal to the concentration of hydroxide ions now in the solution.
Use this value in the equation for pOH:
Remember that the sum of pH and pOH is always 14. To find the pH, subtract the pOH from 14.
Ammonia is a weak base, meaning that we will require an ICE table in order to determine the pH of the solution.
Let's look at the dissociation of ammonia:
I: Before the reaction proceeds, ammonia has a concentration of 0.02M. No product has yet been made.
C: When the reaction is at equilibrium, the products will increase by a concentration of
E: By setting the equilibrium expression equal to the base dissociation constant, we can solve for the value of
Note: because the value for
Keep in mind that
Use this value in the equation for pOH:
Remember that the sum of pH and pOH is always 14. To find the pH, subtract the pOH from 14.
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You find a bottle in a lab that has a 
solution of acid. The acid has the following dissociative properties:
What is the pH of this solution?
You find a bottle in a lab that has a
What is the pH of this solution?
is a strong acid, meaning it will completely dissociate in solution. As such, the concentration of the acid will be equal to the proton concentration. Thus, to find pH, you should just plug the molar concentration of the acid solution into the pH formula.
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What is the pOH of a solution containing a hydrogen ion concentration of 
?
What is the pOH of a solution containing a hydrogen ion concentration of
We can find the pOH by first finding the pH.
Use the given hydrogen ion concentration to find the pH:
We know that pH and pOH will always sum to equal 14, allowing us to find the pOH.
We can find the pOH by first finding the pH.
Use the given hydrogen ion concentration to find the pH:
We know that pH and pOH will always sum to equal 14, allowing us to find the pOH.
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Calculate the pH of the following solution at 
:
Calculate the pH of the following solution at
Use the the dissociation constant for water 
to calculate the concentration of hydrogen ions and then convert to the pH scale.
Rearrange the dissociation constant to solve for the hydrogen ion concentration:
Plug in the given concentrations to find the actual hydrogen ion concentration:
Convert the hydrogen ion concentration to pH scale:
Use the the dissociation constant for water
Rearrange the dissociation constant to solve for the hydrogen ion concentration:
Plug in the given concentrations to find the actual hydrogen ion concentration:
Convert the hydrogen ion concentration to pH scale:
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Calculate the pOH and hydroxide ion concentration in an organism whose blood pH was measured to be 8.00 at 
.
Calculate the pOH and hydroxide ion concentration in an organism whose blood pH was measured to be 8.00 at
To find the pOH note that 
. Therefore one can solve for 
. Plug in the value of the organism's blood pH and solve to get 
We find the concentration of hydroxide ions based on the formula for pOH:
.
To find the pOH note that
We find the concentration of hydroxide ions based on the formula for pOH:
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Calculate the 
of a 
solution.
Calculate the
Relevant equations:
is a strong acid, so 
Combine equations:
Plug in values:
Relevant equations:
Combine equations:
Plug in values:
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A sample of gastric juice has a pH of 2.5. What is the hydrogen ion concentration in this secretion?
A sample of gastric juice has a pH of 2.5. What is the hydrogen ion concentration in this secretion?
The concentration of hydrogen ions must lie somewhere between and ; alternatively stated, it is between and . The pH of a solution with hydrogen ion concentration of will be 3, and the pH of a solution with hydrogen ion concentration will be 2; thus, our concentration must lie between these two values, since our pH is 2.5
To find the exact concentration, you must be familiar with the logarithmic scale. A difference of 0.5 is equivalent to a log of 3.
Our answer must therefore be , or .
We can calculate the pH in reverse to check our answer.
The concentration of hydrogen ions must lie somewhere between
To find the exact concentration, you must be familiar with the logarithmic scale. A difference of 0.5 is equivalent to a log of 3.
Our answer must therefore be
We can calculate the pH in reverse to check our answer.
Compare your answer with the correct one above
Sodium hydroxide is a strong base. What is the pH of a 0.02M sodium hydroxide solution?
Sodium hydroxide is a strong base. What is the pH of a 0.02M sodium hydroxide solution?
Since sodium hydroxide is a strong base, it will dissociate completely in water. This means that the concentration of the base will be equal to the concentration of hydroxide ions after the reaction runs to completion.
We can find the concentration of hydroxide ions via stoichiometry. One hydroxide ion is created from each molecule of sodium hydroxide that dissociates.
Since we have the concentration of hydroxide ions, we can solve for the pOH of the solution.
The question asks us to find the pH of the solution, so we will need to convert pOH to pH. To do so, we simply subtract the pOH from 14.
The pH of the solution is 12.3. Because sodium hydroxide is a strong base, it makes sense that the pH is above 7.
Since sodium hydroxide is a strong base, it will dissociate completely in water. This means that the concentration of the base will be equal to the concentration of hydroxide ions after the reaction runs to completion.
We can find the concentration of hydroxide ions via stoichiometry. One hydroxide ion is created from each molecule of sodium hydroxide that dissociates.
Since we have the concentration of hydroxide ions, we can solve for the pOH of the solution.
The question asks us to find the pH of the solution, so we will need to convert pOH to pH. To do so, we simply subtract the pOH from 14.
The pH of the solution is 12.3. Because sodium hydroxide is a strong base, it makes sense that the pH is above 7.
Compare your answer with the correct one above
Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
The pH of a solution of is lowered from 4 to 3, and then from 3 to 2. Which of the following is the most accurate description of what happens during these transitions?
Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
The pH of a solution of
The pH scale is logarithmic. Every pH unit drop corresponds to a tenfold increase in protons.
The pH scale is logarithmic. Every pH unit drop corresponds to a tenfold increase in protons.
Compare your answer with the correct one above
Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
A scientist is studying an aqueous sample of , and finds that the hydroxide concentration is . Which of the following is true?
Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
A scientist is studying an aqueous sample of
Given the hydroxide ion concentration, we will need to work using pOH to find the pH. We know that the sum of pH and pOH is equal to 14.
Use our value for the concentration to find the pOH.
Now that we have the pOH, we can use it to solve for the pH.
Given the hydroxide ion concentration, we will need to work using pOH to find the pH. We know that the sum of pH and pOH is equal to 14.
Use our value for the concentration to find the pOH.
Now that we have the pOH, we can use it to solve for the pH.
Compare your answer with the correct one above