30 Questions
What is the pH range considered acidic?
0 down to 7
Which of the following has a pH value of 1.2?
Stomach acid
What is the pH of most plants' preferred soil?
5.5 to 7.5
Which statement about pH is correct?
If there's no water, pH has no meaning.
What does a substance with a pH of 9 indicate?
Basic
What is the pH of hydrochloric acid found in the stomach?
~1.2
What major classes of organic molecules are all cells made from?
Nucleic acids, proteins, carbohydrates, and lipids
Structurally, plant and animal cells are very similar because they are both:
Eukaryotic cells
What is a major structural difference between plant and animal cells?
Plant cells have chloroplasts
Which organelle is typically found in animal cells but rarely seen in plant cells?
Lysosomes
What type of organisms do prokaryotic cells include?
Bacteria and archaea
Which type of cells contain membrane-bound compartments called organelles?
Eukaryotic cells
What does the equilibrium constant reveal about a weak acid or a buffer?
The strength of the weak acid or the buffer
How can the pH of a buffer solution be calculated?
From the concentration of [H+]
What determines the effectiveness of a buffer solution?
The Ka value being similar to the desired pH
What is the Henderson-Hasselbalch equation used for in buffer calculations?
To find the concentration ratio of base to acid in a buffer
How is pH calculated from the H3O+ concentration in an equilibrium solution?
$pH = - ext{log}([H+])$
What must be approximately equal for a buffer to be most effective?
The amounts of acid and its conjugate base
What is the process where substances move from an area of high concentration to an area of low concentration?
Diffusion
Which process involves the movement of water into or out of cells?
Osmosis
What is the importance of diffusion in living things?
Transporting substances in and out of cells
Which cellular transport process involves the use of carrier proteins to facilitate substance movement?
Active transport
In dynamic homeostasis, how do cells maintain specific internal environments?
Through negative feedback loops
Which video exemplifies the comparison between active and passive transport?
Endocytosis, Exocytosis, and SodiumPotassium pump
What is the most accurate method for measuring pH?
Using a pH meter
What did Danish biochemist Søren Peter Lauritz Sørensen propose in 1909 regarding pH calculation?
pH = - log [H+]
In which units is the hydrogen ion concentration represented in the pH equation?
Moles per liter solution
Why is the color change observed on pH test strips different?
Depends on the type of indicator dye used
Which method is generally used in schools and labs for measuring pH?
Using a pH meter
What can affect the accuracy of pH test kits?
Other chemicals present in the sample
Study Notes
Buffer Solutions
- The pH of a buffer solution can be calculated using the equilibrium constant (K) and the initial concentration of the acid.
- The equilibrium constant (K) reveals the strength of the weak acid or the buffer.
- An effective buffer should be made of an acid and its conjugate base or a base and its conjugate acid with similar Ka values to the desired pH.
- The Henderson-Hasselbalch equation is used to determine the exact ratio of the conjugate base to the acid for the desired pH.
pH Calculation
- pH can be calculated from the concentration of [H+] using the equation: pH = - log ([H+])
- The pH of a solution can be calculated using the Ka value and the equilibrium equation.
pH Values
- A pH value around 7 is considered neutral.
- pH values range from 0 (acidic) to 14 (basic).
- The closer the pH is to 0 or 14, the greater its acidity or basicity, respectively.
- Many common cleaners are basic, with a very high pH.
- Blood is close to neutral but is slightly basic.
- Most fruits, vegetables, and body fluids are acidic.
pH Measurement
- pH can be measured using pH paper or a pH meter.
- pH paper test strips can be used to test the pH of substances, with the color of the test strips corresponding to a pH range.
- pH test kits are available to test liquids, but may be affected by other chemicals in a sample.
- pH meters are more accurate than test papers or kits, but require calibration.
pH Equation
- The pH equation was proposed in 1909 by Søren Peter Lauritz Sørensen: pH = - log [H+]
- The equation calculates the pH of a solution based on the hydrogen ion concentration in units of moles per liter.
Cell Types
- Plant cells are usually larger than animal cells and contain structures such as chloroplasts, cell walls, and large vacuoles.
- Animal cells have organelles such as centrioles, lysosomes, microvilli, cilia, and filaments that are absent in plant cells.
- Prokaryotic cells lack a nucleus and membranous organelles, and include all bacteria and archaea.
- Eukaryotic cells contain a nucleus and membrane-bound organelles, and include fungi, animals, and plants as well as some unicellular organisms.
Cellular Transport
- Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
- Active transport involves the use of special carrier proteins to facilitate the movement of substances across cell membranes.
- Passive transport includes diffusion and facilitated diffusion.
- Osmosis is the specific movement of water into or out of cells.
Learn how to calculate the pH of a buffer solution using the equilibrium constant and initial acid concentration. Understand how the equilibrium constant indicates the strength of a weak acid or buffer, and how to determine the concentration of [H+] using Ka. Explore how the pH can be calculated from [H+] concentration, and what makes a buffer effective.
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