Acids And Bases Flashcards
Define a Brønsted-Lowry acid.
A Brønsted-Lowry acid is a proton donor.
Give an example of a Brønsted-Lowry acid.
Ammonium ions (NH4+).
Define a Brønsted-Lowry base.
A Brønsted-Lowry base is a proton acceptor.
Give an example of a Brønsted-Lowry base.
Hydroxide ions (OH-).
Describe the relationship between acid strength and dissociation.
A strong acid completely dissociates to ions in solution, while a weak acid only slightly dissociates.
What pH range is associated with strong acids?
Strong acids have a pH range of 0-1.
What pH range is associated with weak acids?
Weak acids have a pH range of 3-5.
Explain the pH range for strong bases.
Strong bases have a pH range of 12-14.
Explain the pH range for weak bases.
Weak bases have a pH range of 9-11.
How can substances be classified as acids or bases?
Substances can be classified as acids or bases based on their interaction with protons.
What does acid strength not refer to?
Acid strength does not refer to the concentration of a solution.
Define pH.
pH is a measure of acidity and alkalinity, represented on a logarithmic scale from 0 to 14, indicating the concentration of H+ ions in a solution.
Describe the significance of a pH of 0.
A pH of 0 indicates an acidic solution with a high concentration of H+ ions.
Describe the significance of a pH of 14.
A pH of 14 indicates a basic solution with a low concentration of H+ ions.
How can the concentration of H+ ions be determined?
The concentration of H+ ions can be determined if the pH of the solution is known.
Explain the relationship between strong acids and H+ ion concentration.
The concentration of H+ ions in a solution is equivalent to the concentration of a strong acid, as strong acids completely dissociate into ions.
What is the ionic product of water (Kw) at 25°C?
At 25°C, the ionic product of water (Kw) has a constant value of 1 x 10^-14.
How does temperature affect the ionic product of water?
As temperature changes, the value of the ionic product of water (Kw) also changes.
Describe the nature of the forward reaction in the equilibrium of water.
The forward reaction in the equilibrium of water is endothermic and is favored when the temperature of the water is increased.
What happens to H+ ion production as the temperature of water increases?
As the temperature of water increases, more H+ ions are produced, making the water more acidic.
Describe the dissociation of weak acids and bases in solution.
Weak acids and bases only slightly dissociate in solution, forming an equilibrium mixture.
Define the equilibrium dissociation constant for weak acids.
The equilibrium dissociation constant for weak acids is denoted as Ka.
How can pKa be used in relation to weak acids and bases?
pKa can be used to find the concentration of hydrogen ions
Explain the method to find pH when HA is in excess.
When HA is in excess, use the concentrations of [HA] and [A - ] along with Ka to find [H + ], then calculate pH.
What is the approach when A - is in excess?
When A - is in excess, use the ion product of water, Kw, to find [H + ], then calculate pH.
How is pKa related to pH when HA equals A - ?
When HA equals A - , pKa is equal to pH, so you can find pKa directly.
Describe a pH titration curve.
A pH titration curve shows how the pH of a solution changes during an acid-base reaction.
What is the significance of the neutralisation point in a titration curve?
The neutralisation point is identified as a large vertical section in the titration curve, indicating the equivalence point of the acid-base reaction.
Describe the process of investigating the pH of an acid-base reaction.
Alkali is slowly added to an acid while measuring the pH with a pH probe, or vice versa. Smaller added volumes yield a more accurate pH curve.
Define the neutralization point for a strong acid and strong base reaction.
The neutralization point for a strong acid and strong base reaction occurs around pH 7.
How does the neutralization point differ between strong acids and weak bases?
For a strong acid and weak base reaction, the neutralization point is less than pH 7, indicating a more acidic solution.
What is the expected pH when a weak acid reacts with a strong base?
The expected pH when a weak acid reacts with a strong base is greater than pH 7, indicating a more basic solution.
Explain the neutralization point for weak acid and weak base combinations.
The neutralization point for weak acid and weak base combinations is normally around pH 7, but it can be hard to determine accurately.
How does the volume of alkali added affect the accuracy of the pH curve?
The smaller the added volumes of alkali, the more accurate the pH curve produced during the investigation.
Describe the role of specific indicators in chemical reactions.
Specific indicators are used for specific reactions as they indicate a pH change within a certain range.
Define methyl orange and its use in titrations.
Methyl orange is an indicator used for reactions with a more acidic neutralisation point, appearing orange in acids and turning yellow at the neutralisation point.
Explain the color change of phenolphthalein in different pH environments.
Phenolphthalein is pink in alkalis and turns colourless at the neutralisation point, making it suitable for reactions with a more basic neutralisation point.
How does the choice of indicator affect titration results?
The correct indicator must be selected based on the chemicals used in a titration to accurately reflect the pH change.
What components make up an acidic buffer solution?
An acidic buffer solution contains a weak acid and the salt of that weak acid.
Identify the components of a basic buffer solution.
A basic buffer solution consists of a weak base and the salt of that weak base.
Describe the function of a buffer solution when an acid is added.
When an acid is added to a buffer solution, it resists a change in pH by reacting with the buffer components, such as ethanoate ions, to form the weak acid.
How does a buffer solution maintain pH stability?
A buffer solution maintains pH stability by neutralizing small amounts of added acid or base, preventing significant changes in pH.
Define a buffer solution in terms of pH changes.
A buffer solution is defined as a solution that can resist changes in pH when small volumes of acid or base are added.
Describe the process of calculating pH for an acid and base buffer system.
Find the number of moles of each species, calculate their concentration at equilibrium using the total volume, and use Ka to find [H+] and therefore pH.
How does adding small volumes of acid affect the pH of a buffer solution?
Adding small amounts of acid (H+) increases the concentration of the acid in the buffer solution, making the overall solution slightly more acidic.
What happens to the pH of a buffer solution when small amounts of base are added?
Adding small amounts of base (OH-) decreases the concentration of acid in the buffer solution, making the overall solution slightly more basic.
Define the role of buffer solutions in biological systems.
Buffer solutions help maintain a specific pH, which is crucial for the proper functioning of enzymes and reactions in living organisms.
Explain the significance of buffer solutions in nature.
Buffer solutions are important for regulating systems in nature, ensuring that biological processes can occur within the required pH range.
How do you calculate pH for an acid and salt buffer system?
Find the moles of the salt and use Ka to determine the pH.
What is the typical change in pH when small volumes of acid or base are added to a buffer solution?
The pH of a buffer solution typically changes by about 0.1 or 0.01 units when small volumes of acid or base are added.
