Ch. 2 Water
Studied by 0 people
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/46
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced | Call with Kai |
|---|
No analytics yet
Send a link to your students to track their progress
47 Terms
Covalent bond
A bond formed by sharing electrons between atoms
Nonpolar covalent bond
Electrons are shared equally between atoms
Polar covalent bond
Electrons are shared unequally due to electronegativity differences
Electronegativity
An atom’s attraction for shared electrons
Oxygen and nitrogen
Which atoms are highly electronegative in biology?
Bent shape + oxygen pulls electrons more strongly
Why is water polar?
Dipole moment
Separation of partial charges in a molecule
Hydrogen bonded to O, N, or F
What atoms form hydrogen bonds?
Weak individually, strong collectively
Are hydrogen bonds strong or weak?
Extensive hydrogen bonding
What causes water’s high boiling point?
Hydrogen bonds hold molecules farther apart in a lattice
Why is ice less dense than liquid water?
DNA, proteins, cellulose
What biological structures rely on hydrogen bonds?
Hydrogen bonding between water molecules
Why does water have high cohesion?
They form fewer hydrogen bonds
Why do other hydrides have lower boiling points than water?
Bonds become more ordered and spaced
What happens to hydrogen bonding when water freezes?
Hydrophobic effect
Nonpolar molecules avoid water and cluster together
Water prefers hydrogen bonding with itself
Why don’t oil and water mix?
Amphipathic molecule
Has hydrophobic and hydrophilic regions
Micelle
Spherical cluster of amphipathic molecules in water
Cell membranes and protein folding
What structures rely on the hydrophobic effect?
Ionic and polar molecules
What types of molecules dissolve in water?
Water surrounds and stabilizes ions (solvation)
Why do ionic compounds dissolve?
Hydrogen bonding with water
Why do polar molecules dissolve?
Nonpolar molecules
What types of molecules do NOT dissolve well?
H2O ⇌ H+ + OH-
What reaction occurs in pure water?
They are equal
What is true about [H+] and [OH-] in pure water?
Acid
Increases hydrogen ion concentration
Base
Decreases hydrogen ion concentration
Strong fully dissociates; weak partially dissociates
Strong vs weak acid difference?
[H⁺] > [OH⁻]
When is a solution acidic?
[OH⁻] > [H⁺]
When is a solution basic?
pH equation
pH = −log[H⁺]
Hydrogen ion concentration
What does pH measure?
7
What is a neutral pH?
<7
What pH values are acidic?
>7
What pH values are basic?
10x
How much does acidity change per pH unit?
pKa
-log(Ka), measure of acid strength
Stronger acid
Lower pKa means what?
Buffer
Weak acid + conjugate base that resists pH change
When pH ≈ pKa
When is buffering strongest?
±1 pH unit of pKa
Buffer effective range?
Henderson–Hasselbalch equation
pH = pKa + log([A⁻]/[HA])
pH increases
What happens if [A⁻] increases?
Titration curve
Graph of pH vs added acid/base
At the pKa region
Where is buffering strongest on a titration curve?
Acid neutralized by base
What happens at equivalence point?
Note 
Flashcards (26)