Case 4 Too much or too little
dinsdag 16 september 2025 12:02
Point of interest
- Buffers
- Calculating with ph.
- Weak and stronger acids/alkaline
- Enzymes in blood and it's functions
- How does drugs interact with blood
- Osmotic value
- Hemoglobin
- Osmoses
- Why did the experiment failed (blood cells burst)
- PBS
- Why did pbs work
Learning goals
- What is a buffer (How do they work, where do we use them, what are they, which are there, why do we use them)
- What is PH and how do we calculate with it (acids/alkaline)
- Weak and stronger acids/alkaline
- Enzymes in blood and it's functions
- How does PH affect a reaction, in human biochemical systems.
- What is osmolarity, and how does it work
- Basic components of blood
- Henderson Hasselbach equation (calculate)
- Why did it fail with water and success with pbs.
What is a buffer?
A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or
base, thus maintaining the pH of the solution relatively stable.
To effectively maintain a pH range, a buffer must consist of a weak conjugate acid-base pair, meaning either a weak acid and its conjugate base, or a weak
base and its conjugate acid. The use of one or the other will simply depend upon the desired pH when preparing the buffer.
How buffers work
A mixture of acetic acid and sodium acetate is acidic because the Ka of acetic acid is greater than the Kb of its conjugate base acetate. It is a buffer because it
contains both the weak acid and its salt. Hence (vandaar), it acts to keep the hydronium ion concentration (and the pH) almost constant by the addition of
either a small amount of a strong acid or a strong base. If we add a base such as sodium hydroxide, the hydroxide ions react with the few hydronium ions
present. The more of the acetic acid react with water, restoring the hydronium ion concentration almost to its original value.
CH3CO2H(𝑎𝑞)+H2O(𝑙)⟶H3O+(𝑎𝑞)+CH3CO−2(𝑎𝑞)
The pH changes very little. If we add an acid such as hydrochloric acid, most of the hydronium ions from the hydrochloric acid combine with acetate ions,
forming acetic acid molecules.
H3O+(𝑎𝑞)+CH3CO−2(𝑎𝑞)⟶CH3CO2H(𝑎𝑞)+H2O(𝑙)
Thus, there is very little increase in the concentration of the hydronium ion, and the pH remains practically unchanged.
Composition - A buffer solution contains a weak acid (HA) and its conjugate base (A-).
Added Acid - When a strong acid is added, it introduces excess H+ ions
Neutralization - The conjugate base (A-) in the buffer reacts with these excess h+ ions to form more weak acid (HA)
A- + H+ --> HA
Outcome - The increase in the concentration of HA prevents a significant rise in H+ concentration, thus resisting the change in ph.
Where do we use them
Buffers are used to stabilize pH in many industrial processes like dyeing fabrics and manufacturing cosmetics, as well as in biological research for cell culture
and electrophoresis. They are also found in everyday products like antacids and buffered aspirin, and in fermentation and food preservation to maintain
specific conditions for chemical reactions and product stability.
Why do we use them?
We use buffers to maintain a stable and consistent pH level in chemical and biological systems, as many reactions and processes are sensitive to even small
PH changes. Buffers achieve this by neutralizing added acids or bases, which prevents a rapid and dramatic shift in pH and ensures that reactions can
proceed under their optimal conditions.
What is pH and how do we calculate with it (acids/alkaline
Ph is a scale from 0 to 14 that measures how acidic or basic (alkaline) a liquid solution is, with 7 being neutral. It indicates the concentration of hydrogen
ions (h+) is a solution, more H+ means more acidity while more hydroxyl ions (OH-) mean a solution is basic. Each whole number change on the pH scale
represents a ten-fold difference in acidity or basicity
Understanding the pH scale
Acids - Solutions with a pH less than 7 are acidic. Acids have a higher concentration of hydrogen ions.
Neutral - A pH of 7 is neutral. Pure water at 25 degree is neutral, containing equal amounts of hydrogen and hydroxyl ions.
Bases (Alkaline) - Solutions with a pH greater than 7 are basic or alkaline. Bases have higher concentration of hydroxyl ions.
The logarithmic nature of pH - The pH scale is logarithmic, meaning each step represents a tenfold change. A solution with a pH of 5 is ten times more acidic
than a solution with a pH of 6. A solution with a pH of 4 is 100 times more acidic than a solution with a pH of 6.
How to calculate with pH
Steps to calculate with pH
1. Find the hydronium ion concentration (H3O+) - this is mostly given in moles per liter.
2. Use the formula - pH = -log[H3O+]
3. Calculate the result - is [H3O+] is a simple power of 10, the pH is simply the positive exponent
If [H3O+] is not a simple power of 10, such as 0,0062 x10^3, use a calculator to find the logarithm and take its negative.
Weak and stronger acids/alkalizes
Weak acid/bases
Weak acids and weak alkalis or bases are substances that do not fully dissociate or ionize, in water, meaning only a portion of the molecules break apart into
ions to release H+ for acids and OH- for alkalis ions. This partial ionization results in a lower concentrations of H+ or OH- ions, leading to pH values closer to
neutral (for weak acids) or moderately basic (for weak alkalis) compered to their strong counterparts
Weak acids - Ac acid that only partially ionized in water.
Dissociation - The ionization reaction is a reversible process, with the majority of molecules remaining undissociated
PH - Weak acids have a pH value generally between 4 and 6
Examples - Ethanoic acid, citric acid
Reaction rate - Due to the lower concentration of H+ ions, they react more slowly than strong acids with substances like metals and metal carbonates.
Weak bases - A base that only partially dissociates into ions with water.
Ionization - Like weak acids, the ionization of weak bases is a reversible equilibrium (evenwicht) process, with only some molecules producing OH- ions.
PH - Weak bases have pH values typically ranging from 8 to 11
Strong acid/bases
Strong acids and strong alkalis are completely ionized in water, producing a high concentration of hydrogen ions (H+) for acids or hydroxide ions (OH-) for
alkalis. Which results in very low or very high pH values.
Strong acids - A strong acid is a substance that completely or nearly completely dissociates (breaks apart into ions) when dissolved in water, releasing a high
dinsdag 16 september 2025 12:02
Point of interest
- Buffers
- Calculating with ph.
- Weak and stronger acids/alkaline
- Enzymes in blood and it's functions
- How does drugs interact with blood
- Osmotic value
- Hemoglobin
- Osmoses
- Why did the experiment failed (blood cells burst)
- PBS
- Why did pbs work
Learning goals
- What is a buffer (How do they work, where do we use them, what are they, which are there, why do we use them)
- What is PH and how do we calculate with it (acids/alkaline)
- Weak and stronger acids/alkaline
- Enzymes in blood and it's functions
- How does PH affect a reaction, in human biochemical systems.
- What is osmolarity, and how does it work
- Basic components of blood
- Henderson Hasselbach equation (calculate)
- Why did it fail with water and success with pbs.
What is a buffer?
A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or
base, thus maintaining the pH of the solution relatively stable.
To effectively maintain a pH range, a buffer must consist of a weak conjugate acid-base pair, meaning either a weak acid and its conjugate base, or a weak
base and its conjugate acid. The use of one or the other will simply depend upon the desired pH when preparing the buffer.
How buffers work
A mixture of acetic acid and sodium acetate is acidic because the Ka of acetic acid is greater than the Kb of its conjugate base acetate. It is a buffer because it
contains both the weak acid and its salt. Hence (vandaar), it acts to keep the hydronium ion concentration (and the pH) almost constant by the addition of
either a small amount of a strong acid or a strong base. If we add a base such as sodium hydroxide, the hydroxide ions react with the few hydronium ions
present. The more of the acetic acid react with water, restoring the hydronium ion concentration almost to its original value.
CH3CO2H(𝑎𝑞)+H2O(𝑙)⟶H3O+(𝑎𝑞)+CH3CO−2(𝑎𝑞)
The pH changes very little. If we add an acid such as hydrochloric acid, most of the hydronium ions from the hydrochloric acid combine with acetate ions,
forming acetic acid molecules.
H3O+(𝑎𝑞)+CH3CO−2(𝑎𝑞)⟶CH3CO2H(𝑎𝑞)+H2O(𝑙)
Thus, there is very little increase in the concentration of the hydronium ion, and the pH remains practically unchanged.
Composition - A buffer solution contains a weak acid (HA) and its conjugate base (A-).
Added Acid - When a strong acid is added, it introduces excess H+ ions
Neutralization - The conjugate base (A-) in the buffer reacts with these excess h+ ions to form more weak acid (HA)
A- + H+ --> HA
Outcome - The increase in the concentration of HA prevents a significant rise in H+ concentration, thus resisting the change in ph.
Where do we use them
Buffers are used to stabilize pH in many industrial processes like dyeing fabrics and manufacturing cosmetics, as well as in biological research for cell culture
and electrophoresis. They are also found in everyday products like antacids and buffered aspirin, and in fermentation and food preservation to maintain
specific conditions for chemical reactions and product stability.
Why do we use them?
We use buffers to maintain a stable and consistent pH level in chemical and biological systems, as many reactions and processes are sensitive to even small
PH changes. Buffers achieve this by neutralizing added acids or bases, which prevents a rapid and dramatic shift in pH and ensures that reactions can
proceed under their optimal conditions.
What is pH and how do we calculate with it (acids/alkaline
Ph is a scale from 0 to 14 that measures how acidic or basic (alkaline) a liquid solution is, with 7 being neutral. It indicates the concentration of hydrogen
ions (h+) is a solution, more H+ means more acidity while more hydroxyl ions (OH-) mean a solution is basic. Each whole number change on the pH scale
represents a ten-fold difference in acidity or basicity
Understanding the pH scale
Acids - Solutions with a pH less than 7 are acidic. Acids have a higher concentration of hydrogen ions.
Neutral - A pH of 7 is neutral. Pure water at 25 degree is neutral, containing equal amounts of hydrogen and hydroxyl ions.
Bases (Alkaline) - Solutions with a pH greater than 7 are basic or alkaline. Bases have higher concentration of hydroxyl ions.
The logarithmic nature of pH - The pH scale is logarithmic, meaning each step represents a tenfold change. A solution with a pH of 5 is ten times more acidic
than a solution with a pH of 6. A solution with a pH of 4 is 100 times more acidic than a solution with a pH of 6.
How to calculate with pH
Steps to calculate with pH
1. Find the hydronium ion concentration (H3O+) - this is mostly given in moles per liter.
2. Use the formula - pH = -log[H3O+]
3. Calculate the result - is [H3O+] is a simple power of 10, the pH is simply the positive exponent
If [H3O+] is not a simple power of 10, such as 0,0062 x10^3, use a calculator to find the logarithm and take its negative.
Weak and stronger acids/alkalizes
Weak acid/bases
Weak acids and weak alkalis or bases are substances that do not fully dissociate or ionize, in water, meaning only a portion of the molecules break apart into
ions to release H+ for acids and OH- for alkalis ions. This partial ionization results in a lower concentrations of H+ or OH- ions, leading to pH values closer to
neutral (for weak acids) or moderately basic (for weak alkalis) compered to their strong counterparts
Weak acids - Ac acid that only partially ionized in water.
Dissociation - The ionization reaction is a reversible process, with the majority of molecules remaining undissociated
PH - Weak acids have a pH value generally between 4 and 6
Examples - Ethanoic acid, citric acid
Reaction rate - Due to the lower concentration of H+ ions, they react more slowly than strong acids with substances like metals and metal carbonates.
Weak bases - A base that only partially dissociates into ions with water.
Ionization - Like weak acids, the ionization of weak bases is a reversible equilibrium (evenwicht) process, with only some molecules producing OH- ions.
PH - Weak bases have pH values typically ranging from 8 to 11
Strong acid/bases
Strong acids and strong alkalis are completely ionized in water, producing a high concentration of hydrogen ions (H+) for acids or hydroxide ions (OH-) for
alkalis. Which results in very low or very high pH values.
Strong acids - A strong acid is a substance that completely or nearly completely dissociates (breaks apart into ions) when dissolved in water, releasing a high
