S03 Properties of Acids and Bases
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/76
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced | Call with Kai | Chat |
|---|
No analytics yet
Send a link to your students to track their progress
77 Terms
Learning Objective 1: Define electrolytes, acids, and bases, and describe the effect of acid/base strength on overall dissociation
What are electrolytes?
Charged molecules.
What are strong electrolytes?
Electrolytes that are completely charged when dissolved in water.
What is an example of a strong electrolyte?
NaCl.
What are weak electrolytes?
Electrolytes in which charged and uncharged forms are in equilibrium in solution.
What is an example of a weak electrolyte?
Acetic acid.
What is an acid?
A proton donor (H⁺ donor).
What is a base?
A proton acceptor (H⁺ acceptor).
What determines the strength of an acid or base?
The degree of dissociation of that molecule in solution.
How do strong acids dissociate in solution?
Completely.
How do weak acids dissociate in solution?
Partially.
Why do weak acids dissociate only partially?
Not all acid molecules present donate their protons.
How do strong bases dissociate in solution?
Completely.
How do weak bases dissociate in solution?
Partially.
What does Ka measure?
The strength of an acid.
How does acid strength relate to Ka?
The stronger the acid, the higher its Ka value.
What happens to acid dissociation as acid strength increases?
The acid dissociates more readily.
What is the equation for pKa?
pKa = −log Ka.
What does Kb measure?
The strength of a base.
How does base strength relate to Kb?
The stronger the base, the higher its Kb value.
What happens to base dissociation as base strength increases?
The base dissociates more readily.
What is the equation for pKb?
pKb = −log Kb.
Learning Objective 2: Define pH and explain the relationship between the pH of the environment and pKa using the Henderson-Hasselbalch equation
What is pH?
A way to quantify the acidity or basicity of a solution.
What does pH measure mathematically?
The negative logarithm of hydronium ion concentration.
What is the equation for pH?
pH = −log[H₃O⁺].
What is the relationship between pH and pOH?
pH + pOH = 14.
What is Kw?
The ionization constant (dissociation constant) of water under pure conditions.
What is the value of Kw?
1.0 × 10⁻¹⁴.
What is pKw?
The negative logarithmic expression associated with Kw.
What is the relationship between pKw, pKa, and pKb?
pKw = pKa + pKb.
What is the value of pKw?
14.
In the Henderson-Hasselbalch equation, what does HA represent?
The conjugate acid.
In the Henderson-Hasselbalch equation, what does A⁻ represent?
The conjugate base.
Is A⁻ always charged?
No; A⁻ is always the conjugate base whether it is charged or not.
What is the Henderson-Hasselbalch equation?
pH = pKa + log([A⁻]/[HA]).
What does HA do in the equilibrium HA ⇌ H⁺ + A⁻?
HA is the acid.
What does A⁻ do in the equilibrium HA ⇌ H⁺ + A⁻?
A⁻ is the base.
What happens to the H⁺ concentration when an acid is added to water?
H⁺ concentration significantly increases.
What happens to a solution when an acid is added to water?
The solution becomes acidic.
What happens to the OH⁻ concentration when a base is added to water?
OH⁻ concentration significantly increases.
What happens to a solution when a base is added to water?
The solution becomes basic.
Why can water or a neutral salt solution not resist pH changes?
It cannot neutralize small amounts of added acid or base.
What is an unbuffered solution?
A solution that cannot resist changes in pH when small amounts of acid or base are added.
Learning Objective 3: Explain how buffers work to maintain relatively constant pH and describe how acid/base titration curves can be used to illustrate the buffering range
What is a buffer?
A combination of substances that allows an aqueous solution to maintain a desired pH at a relatively constant level.
What does a buffer resist?
Changes in pH when small amounts of acids or bases are added.
What is the first component combination of a buffer system?
A weak acid and the conjugate base of that acid.
What is an example of a weak acid/conjugate base buffer?
Acetic acid and sodium acetate.
What is the second component combination of a buffer system?
A weak base and the conjugate acid of that base.
What is an example of a weak base/conjugate acid buffer?
Ammonia and ammonium chloride.
What is a buffer system composed of when using an acid?
A weak acid and the salt of that acid.
What is a buffer system composed of when using a base?
A weak base and the salt of that base.
What happens when additional base is added to a buffer?
The weak acid reacts with and neutralizes the added base.
What happens when additional acid is added to a buffer?
The conjugate base reacts with and neutralizes the added acid.
What is the result when a buffer neutralizes added acid or base?
The pH remains relatively constant.
What is the effective buffering range?
pKa ± 1 pH unit.
Learning Objective 4: Describe the biological buffer systems that maintain pH intracellularly and extracellularly
What is the major acid produced by the body?
Carbonic acid.
What also functions as a buffer in the body?
Carbonic acid.
What ion acts as a buffer in the blood?
Bicarbonate ion.
What does bicarbonate prevent in the blood?
Radical changes in blood pH.
What is the bicarbonate buffer equilibrium?
H₂CO₃ ⇌ H⁺ + HCO₃⁻.
What is the pKa of the bicarbonate buffer system?
6.3.
What primarily maintains intracellular pH?
Inorganic phosphate and proteins.
What is the intracellular phosphate buffer equilibrium shown in the lecture?
H₂PO₄⁻ ⇌ H⁺ + HPO₄²⁻.
What is the pKa of the intracellular phosphate system?
7.2.
Where is NH₃ produced?
From amino acid catabolism or absorption through the intestine.
Why must NH₃ be maintained at very low concentrations in the blood?
NH₃ is toxic to neural tissues.
Where do cells generate and excrete NH₃?
In the kidney and urine.
What determines the proportion of NH₃ generated and excreted in urine?
The acidity (proton concentration) of the blood.
What is the ammonium equilibrium?
NH₃ + H⁺ ⇌ NH₄⁺.
What is the pKa of the ammonium system?
9.25.
Where is HCl secreted?
In the stomach.
What is the role of HCl in the stomach?
It is secreted to ingest proteins.
What happens to HCl when stomach contents reach the small intestines?
HCl is neutralized by bicarbonate.
Why is HCl neutralized in the small intestines?
To prevent degradation of digestive enzymes by HCl.
At what pH is blood maintained?
7.4.
What maintains blood pH at 7.4?
Primary buffers in plasma and secondary buffers in erythrocytes.
What is one primary buffer in plasma?
The carbonic acid/bicarbonate system.
What is the pKa of the carbonic acid/bicarbonate buffer system in plasma?
6.3.