Lab 3: pH and Buffers Flashcards
Define pH
pH is a measure of the concentration of hydrogen ions (H+) in a solution
Describe an acid and an acidic solution
An acid is a substance that donates hydrogen ions (H+) into a solution. Acidic solutions contain a high concentration of hydrogen ions (H+)
Describe a base and basic solution
A base is a substance that binds to hydrogen ions (H+) causing hydroxide ions (OH-) ions to be released. A basic solution has few hydrogen ions (H+)
Explain the relationship between hydrogen ion concentration and pH
pH measures hydrogen ion concentration
The lower the pH means high hydrogen ion (H+) concentration
The higher the pH means the lower the hydrogen ion (H+) concentration
Explain the use of the pH scale
The pH scale is used to describe the acidity or alkalinity of a solution based on the relative concentration of H+.
Explain the use of the pH indicator
A simple way of determining the approximate pH of a solution depending on color changes
Describe the function of a buffer and explain why buffers are important to life.
The function of a buffer is to maintain a particular pH of a solution, even when small amounts of acid or base are added to the solution.
Buffers are used in our blood, in order for us to maintain homeostasis
hydrogen ion
H+/ cation (positively charged ion)
hydroxide ion
OH-/ anion (negatively charged ion)
acid
A substance that donates hydrogen ions (H+) into a solution
base
A substance that binds to hydrogen ions (H+) in a solution causing a release of hydroxide ions (OH-)
alkaline
Basic solutions
neutral
A solution with an equal concentration of H+ and OH-
pH
A measure of the concentration of hydrogen ions (H+) in a solution
pH scale
Used to describe the acidity or alkalinity of a solution based on the relative concentrations of H+
pH indicator
A substance that changes color depending on the pH of the solution, in order to determine the pH of the solution.
anthocyanins
a pH indicator due to a group of pigments found in red cabbage that turns it the color purple
pH buffer
a substance that can maintain a particular pH when small amounts of an acid or a base are added
What are the two components of a buffer?
- A weak acid that releases H+
2. A weak base that binds to H+
How does a buffer work if the solution becomes basic?
If the solution becomes basic, the buffer donates H+ ions in order to increase the H+ concentration.
How does a buffer work if the solution becomes more acidic?
If the solution becomes more acids, the buffer will bind to H+ ions producing more OH- ion s in the solution. Thus decreasing the H+ concentration
buffering capacity
The ability of a buffer to resist changes in pH with the addition of increasing amounts of acid or base
pH range
A certain range that a buffer can successful work within
pH scale range for acidic solutions
0 to 6
pH scale range for basic solutions
8 to 14
pH scale range for neutral solutions
7
What is the range of the pH scale
0 to 14
alkaline
a (basic) solution that contains a low concentration of H+ ions
acidic
a solution that contains a high concentration of H+ ions
basic
a solution that contains a low concentration of H+ ions
titration curve
pH curve that is a graph that describes how pH changes during various acid-base titrations
phenol red
a pH indicator
