pH Fundamentals
This equation always relates pH and pOH in an aqueous solution at 25°C.
What is pH + pOH = 14?
Under Brønsted acid-base theory, this is what an acid does with a proton.
What is donate it (an acid is a proton donor)?
This equation is used to calculate the pH of a solution containing known amounts of a weak acid and its conjugate base.
What is Henderson-Hasselbalch
This term describes an acid, like acetic acid, that has only one dissociable proton and therefore only 2 possible ionic forms.
What is a monoprotic acid?
This term describes a molecule that has both polar and non-polar properties.
What is amphipathic?
A solution's pH drops from 6 to 4. By what factor has [H+] increased?
What is 100-fold (10²)?
In NH3 + H2O ⇌ NH4+ + OH-, this term describes the relationship between NH3 and NH4+.
What is a conjugate acid-base pair?
This is the reason the Henderson-Hasselbalch equation cannot be used to calculate the pH of a strong acid or base solution.
What is it doesn't account for the ionization of water?
A diprotic acid such as carbonic acid has this many possible ionic forms as it is titrated from H2A to A2-.
What is 3 (H2A, HA-, and A2-)?
These two functional groups on amino acids act as acids or bases and influence the pH of the surrounding aqueous medium.
What are the carboxyl and amino groups?
This pH value is defined as precisely neutral at 25°C, derived from the ionization constant of water.
What is pH 7?
3 weak acids named in the presentation?
HAc, H3PO4, H2CO3
At the inflection point of a titration curve, this relationship holds true between pH and pKa, and between acid and conjugate base concentrations.
What is pH = pKa, with [HA] = [A-]?
On the titration curve of a triprotic acid like phosphoric acid, this many inflection points and this many equivalence points will appear.
What is 3 inflection points and 3 equivalence points?
A compound is more likely to be hydrophilic if it carries many of this type of functional group rather than long nonpolar hydrocarbon chains.
What are polar/ionizable groups (such as -OH, -NH2, -COOH)?
Uncontrolled diabetics often have blood plasma pH below the normal ~7.4, a condition given this name.
What is acidosis?
This constant equals Keq multiplied by [H2O], and expresses acid strength directly as [H+][A-]/[HA].
What is Ka, the acid dissociation constant?
In pure water at 25°C, Kw = [H+][OH⁻] = 1 x 10⁻¹⁴. Using this, what are [H+] and [OH⁻] individually in pure water?
What is 1 x 10⁻⁷ M for each (since [H+] = [OH⁻] in pure water)?
For phosphoric acid, with pKa1 = 2.12, pKa2 = 7.21, and pKa3 = 11.66, this many distinct buffering plateaus (steps) will appear on its titration curve. *Draw it*
What is 3 steps/plateaus?
Comparing three amino acids with identical backbones but side chains of -CH3, -CH(CH3)2, and -CH2-C6H5, this side chain gives the greatest water solubility.
What is -CH3 (the smallest, least hydrophobic side chain, as in alanine)?
A solution has [H+] = 3.2 x 10⁻⁵ M. Calculate its pH to two decimal places.
What is pH ≈ 4.49?
Acetic acid has a Ka of 1.8 x 10⁻⁵. Calculate its pKa.
What is 4.74?
A solution has [OH⁻] = 4.0 x 10⁻³ M. Calculate its pH.
What is pH ≈ 11.60? (pOH = -log(4.0x10⁻³) ≈ 2.40, so pH = 14 - 2.40 = 11.60)
You are asked to sketch the titration curve for a diprotic acid with pKa1 = 3.0 and pKa2 = 8.0. Describe where the two inflection points fall and what is true of the acid/conjugate-base concentrations at each.
What is: an inflection point at pH 3.0 where [H2A] = [HA-], and a second inflection point at pH 8.0 where [HA-] = [A2-], with a steep equivalence-point jump in pH following each inflection point?
This term describes substances, like sugars and salts, that readily dissolve in water because they interact favorably with it, in contrast to hydrophobic substances.
What is hydrophilic?