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Flashcards in Chapter 2 Deck (20):
1

How many hydrogen bonds does liquid H2O have?

3.4

2

How many hydrogen bonds does ice have?

4.0

3

How fast do hydrogen bonds break and reform?

pico second (10^-12)

4

What kind of interaction is a hydrogen bond?

Intermolecular (electrostatic) interaction

5

Hydrogen bonds mostly occur between what atoms?

H, O, N, F

6

Explain why ice floats on water

Ice forms crystal lattice and has 4 fixed hydrogen bonds that are maximally spread apart (less molecules per area, which causes a decreased density) Water constantly makes and breaks hydrogen bonds and averages 3.4 bonds at any moment, but the molecules are able to be positioned much closer together (more molecules per area, which causes increased density)

7

Orientation of hydrogen bonds in liquid water

Straight

8

Orientation of hydrogen bonds in ice

Bent

9

Why is it a bad idea to use NaCl on the sidewalks as a deicer when you run out of CaCl2?

NaCl completely ionizes in water because it is a polar molecule (Na+ and Cl-) salt that forms two ions. CaCl2 ionizes into three molecules and the solute interferes with the hydrogen bond formation (makes the hydrogen bonds weaker).
*Colligative properties

10

What is entropy?

The measure of randomness in a system (deltaS)

11

Example of increased entropy

Boiling

12

Example of decreased entropy

Freezing

13

What orientation of fatty acid formation is favorable in an aqueous solution and why?

Micelle is favored because less nonpolar surface area is interacting with water molecules. Less ordered water is needed to surround the molecule, and allows for an larger entropy (deltaS) overall in the system.

14

Explain how the hydrophobic effect can drive enzymatic reactions in the forward direction.

Hydrophobic effect increases entropy of a system by requiring less ordered water to surround the enzyme and the substrate in aqueous solution if they are both complexed together. This makes the reaction favorable and drives it in the forward direction.

15

Define amphiphillic

Has hydrophobic and hydrophillic ends

16

Define amphipathic

Has polar and nonpolar ends

17

When an acid base problem asks you to estimate, use

Rule of Nines

18

When an acid base problem asks you to calculate, use

Henderson Hasselbach

19

Rule of Nines formulation method

1. Subtract pH from pKa to find the difference, and take the absolute value with normal rounding rules
2. Use the difference to determine the number of nines in the ratio
3. Determine whether the ratio is more protonated or deprotonated
4. Determine if molecule is acidic or basic, and then use the ratio to compare ionized:unionized

20

What is the bicarbonate buffer system?

H2O (l) + CO2 (g) = H2CO3 = H+ + HCO3-