pH and pK - AP Chemistry
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What does a high pK$_a$ indicate about the strength of an acid?
What does a high pK$_a$ indicate about the strength of an acid?
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Weak acid. High pK$_a$ means low ionization tendency.
Weak acid. High pK$_a$ means low ionization tendency.
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What is the pH of a neutral solution at 25°C?
What is the pH of a neutral solution at 25°C?
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pH = 7. Equal concentrations of H$^+$ and OH$^-$ ions.
pH = 7. Equal concentrations of H$^+$ and OH$^-$ ions.
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If $K_a$ is small, is the acid strong or weak?
If $K_a$ is small, is the acid strong or weak?
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Weak acid. Small $K_a$ means limited ionization.
Weak acid. Small $K_a$ means limited ionization.
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Find the pOH of a solution with pH = 2.
Find the pOH of a solution with pH = 2.
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pOH = 12. Using the relationship pH + pOH = 14.
pOH = 12. Using the relationship pH + pOH = 14.
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Calculate the pH of a 0.1 M HCl solution.
Calculate the pH of a 0.1 M HCl solution.
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pH = 1. HCl completely ionizes; [H$^+$] = 0.1 M.
pH = 1. HCl completely ionizes; [H$^+$] = 0.1 M.
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What does a high pK$_a$ indicate about the strength of an acid?
What does a high pK$_a$ indicate about the strength of an acid?
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Weak acid. High pK$_a$ means low ionization tendency.
Weak acid. High pK$_a$ means low ionization tendency.
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What is the pK$_b$ of a strong base?
What is the pK$_b$ of a strong base?
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Low pK$_b$. Strong bases have very negative pK$_b$ values.
Low pK$_b$. Strong bases have very negative pK$_b$ values.
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What is the pH of a 0.1 M acetic acid solution with $K_a = 1.8 \times 10^{-5}$?
What is the pH of a 0.1 M acetic acid solution with $K_a = 1.8 \times 10^{-5}$?
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pH ≈ 2.88. Using the weak acid approximation formula.
pH ≈ 2.88. Using the weak acid approximation formula.
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Identify the term for the negative logarithm of the base dissociation constant.
Identify the term for the negative logarithm of the base dissociation constant.
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pK$_b$. Standard notation for base dissociation constant.
pK$_b$. Standard notation for base dissociation constant.
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Calculate the pK$_b$ for a base with $K_b = 4.5 \times 10^{-8}$.
Calculate the pK$_b$ for a base with $K_b = 4.5 \times 10^{-8}$.
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pK$_b$ ≈ 7.35. Using $\text{pK}_b = -\log(4.5 \times 10^{-8})$.
pK$_b$ ≈ 7.35. Using $\text{pK}_b = -\log(4.5 \times 10^{-8})$.
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What is the formula for calculating pOH?
What is the formula for calculating pOH?
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$\text{pOH} = -\text{log}_{10}[\text{OH}^-]$. Negative log base 10 of hydroxide ion concentration.
$\text{pOH} = -\text{log}_{10}[\text{OH}^-]$. Negative log base 10 of hydroxide ion concentration.
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What is the formula for the ion product of water ($K_w$) at 25°C?
What is the formula for the ion product of water ($K_w$) at 25°C?
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$K_w = 1.0 \times 10^{-14}$. Ion product constant for water at standard temperature.
$K_w = 1.0 \times 10^{-14}$. Ion product constant for water at standard temperature.
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What does a low pK$_b$ indicate about the strength of a base?
What does a low pK$_b$ indicate about the strength of a base?
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Strong base. Low pK$_b$ means high ionization tendency.
Strong base. Low pK$_b$ means high ionization tendency.
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Calculate the [OH$^-$] for a solution with pOH = 8.
Calculate the [OH$^-$] for a solution with pOH = 8.
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[OH$^-$] = $1.0 \times 10^{-8}$ M. Using [OH$^-$] = $10^{-\text{pOH}}$ relationship.
[OH$^-$] = $1.0 \times 10^{-8}$ M. Using [OH$^-$] = $10^{-\text{pOH}}$ relationship.
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What is the relationship between $K_a$ and $pK_a$?
What is the relationship between $K_a$ and $pK_a$?
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$\text{pK}a = -\text{log}{10}(K_a)$. Takes the negative logarithm of the acid constant.
$\text{pK}a = -\text{log}{10}(K_a)$. Takes the negative logarithm of the acid constant.
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Define the term 'acid dissociation constant' ($K_a$).
Define the term 'acid dissociation constant' ($K_a$).
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$K_a$ is the equilibrium constant for the dissociation of an acid. Measures the extent of acid ionization in solution.
$K_a$ is the equilibrium constant for the dissociation of an acid. Measures the extent of acid ionization in solution.
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What is the formula for the base dissociation constant ($K_b$)?
What is the formula for the base dissociation constant ($K_b$)?
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$K_b$ is the equilibrium constant for the dissociation of a base. Measures the extent of base ionization in solution.
$K_b$ is the equilibrium constant for the dissociation of a base. Measures the extent of base ionization in solution.
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Calculate the [H$^+$] for a solution with pH = 6.
Calculate the [H$^+$] for a solution with pH = 6.
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[H$^+$] = $1.0 \times 10^{-6}$ M. Using [H$^+$] = $10^{-\text{pH}}$ relationship.
[H$^+$] = $1.0 \times 10^{-6}$ M. Using [H$^+$] = $10^{-\text{pH}}$ relationship.
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Identify the pH range of a basic solution.
Identify the pH range of a basic solution.
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pH > 7. Higher OH$^-$ concentration than neutral solution.
pH > 7. Higher OH$^-$ concentration than neutral solution.
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Determine the pOH of a solution with [OH$^-$] = $1.0 \times 10^{-4}$ M.
Determine the pOH of a solution with [OH$^-$] = $1.0 \times 10^{-4}$ M.
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pOH = 4. Using $\text{pOH} = -\log(1.0 \times 10^{-4}) = 4$.
pOH = 4. Using $\text{pOH} = -\log(1.0 \times 10^{-4}) = 4$.
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What is the pH of a 0.01 M NH$_3$ solution ($K_b = 1.8 \times 10^{-5}$)?
What is the pH of a 0.01 M NH$_3$ solution ($K_b = 1.8 \times 10^{-5}$)?
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pH ≈ 11.13. Using weak base approximation with given $K_b$.
pH ≈ 11.13. Using weak base approximation with given $K_b$.
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Calculate the pK$_a$ for an acid with $K_a = 3.2 \times 10^{-4}$.
Calculate the pK$_a$ for an acid with $K_a = 3.2 \times 10^{-4}$.
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pK$_a$ ≈ 3.5. Using $\text{pK}_a = -\log(3.2 \times 10^{-4})$.
pK$_a$ ≈ 3.5. Using $\text{pK}_a = -\log(3.2 \times 10^{-4})$.
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If $K_a$ is large, is the acid strong or weak?
If $K_a$ is large, is the acid strong or weak?
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Strong acid. Large $K_a$ means extensive ionization.
Strong acid. Large $K_a$ means extensive ionization.
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Determine the pH of a 0.01 M NaOH solution.
Determine the pH of a 0.01 M NaOH solution.
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pH = 12. NaOH gives [OH$^-$] = 0.01 M, so pOH = 2.
pH = 12. NaOH gives [OH$^-$] = 0.01 M, so pOH = 2.
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Which has a higher pH: 0.1 M HCl or 0.1 M CH$_3$COOH?
Which has a higher pH: 0.1 M HCl or 0.1 M CH$_3$COOH?
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0.1 M CH$_3$COOH. Acetic acid is weak, HCl is strong acid.
0.1 M CH$_3$COOH. Acetic acid is weak, HCl is strong acid.
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Calculate $K_b$ if $K_a = 1.0 \times 10^{-5}$ for a conjugate acid-base pair.
Calculate $K_b$ if $K_a = 1.0 \times 10^{-5}$ for a conjugate acid-base pair.
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$K_b = 1.0 \times 10^{-9}$. Using $K_a \times K_b = 1.0 \times 10^{-14}$.
$K_b = 1.0 \times 10^{-9}$. Using $K_a \times K_b = 1.0 \times 10^{-14}$.
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What is the pH of pure water at 25°C?
What is the pH of pure water at 25°C?
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pH = 7. Autoionization gives equal H$^+$ and OH$^-$.
pH = 7. Autoionization gives equal H$^+$ and OH$^-$.
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Calculate the pH of a solution with [H$^+$] = $1.0 \times 10^{-3}$ M.
Calculate the pH of a solution with [H$^+$] = $1.0 \times 10^{-3}$ M.
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pH = 3. Using $\text{pH} = -\log(1.0 \times 10^{-3}) = 3$.
pH = 3. Using $\text{pH} = -\log(1.0 \times 10^{-3}) = 3$.
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State the relationship between pH and pOH in water at 25°C.
State the relationship between pH and pOH in water at 25°C.
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$\text{pH} + \text{pOH} = 14$. Based on the ion product of water at 25°C.
$\text{pH} + \text{pOH} = 14$. Based on the ion product of water at 25°C.
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If pK$_a$ is 4, what is the strength of the acid?
If pK$_a$ is 4, what is the strength of the acid?
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Weak acid. pK$_a$ = 4 indicates moderate acid strength.
Weak acid. pK$_a$ = 4 indicates moderate acid strength.
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