Ch2 Adaptive Quiz: Water, the Solvent of Life Flashcards
What is the source of polarity of an individual bond?
a relatively large difference in the electronegativities of bonded atoms
How many buffering regions would be seen on a titration curve of a triprotic acid?
3
Why is the concentration of water not accounted for in the calculation of Kh?
The concentration of water is so high (55.5 M) that dissolving CO2 doesn’t change [H2O] very much.
Which is false regarding the properties of ice?
Melting ice has a positive free-energy change at room temperature.
Which statement is false regarding pH?
Protons exist as OH− ions in solution.
Which statement is true about a diprotic acid like H2CO3?
It has two buffering regions, one centered around each of the two pKa values.
Why is oxygen more electronegative than hydrogen?
The shared electrons are more often in the vicinity of the oxygen atom than of the hydrogen.
The Ka of acetic acid is 1.74 × 10−5 (Ac− = acetate ion; HAc = acetic acid).
Ac− + H2O → HAc + OH−
What is the pKa for this reaction?
4.76
The enzyme N-acylethanolamine acid amidase has a pH optimum of 8.5. If a biochemist wants to set up an in vitro assay to screen inhibitors of this enzyme, which buffer system would be BEST?
NH4+/NH3; pKa = 9.25
Which situation does NOT involve a gain in entropy?
the formation of a hydrogen bond between water molecules
What is the pH of a solution with an OH− concentration of 10−9 M?
5
Which statement is true regarding the properties of liquid water?
Evaporating water has greater enthalpy change than melting ice.
