Chapter 2: Water

Question 1

____________ gives water its unusual properties

Answer 1

Hydrogen bonds

Question 2

What is the dissociation energy for hydrogen bonds

Answer 2

23Kj/mol

Question 3

______________ are responsible for water high melting point due to the thermal energy need to break the bonds

Answer 3

Hydrogen Bonds

Question 4

Water forms ____________ with polar solutes

Answer 4

Hydrogen Bonds

Question 5

Hydrogen bonds are strongest when the bonded molecules are oriented in a _______________

Answer 5

Straight line

Question 6

Water interacts electrostatically with _________ solutes

Answer 6

Charged

Question 7

Polar molecules are __________

Answer 7

hydrophilic

Question 8

Nonpolar molecules are ___________

Answer 8

Hydrophobic (such as lipids and waxes)

Question 9

The strength/ forces of ionic interactions in a solution depends on the what formula

Answer 9

F= Q₁ Q/Er² (E for water at 25 Celsius is 78.5)

Question 10

For every nonpolar solvent benzene E is ______

Answer 10

4.6

Question 11

Ionic interaction between dissolved ions are much stronger in less __________ environments

Answer 11

polar

Question 12

Nonpolar gases such as CO₂, O₂, & N₂ are poorly in ________

Answer 12

Water

Question 13

Polar gases such as NH₃, NO, H₂S dissolve easily in ___________

Answer 13

Water

Question 14

Amphipathic

Answer 14

Compounds containing regions that are both polar & nonpolar regions

Question 15

Hydrophobic effect

Answer 15

When the nonpolar regions of the molecules cluster together to make the smallest hydrophobic area to the aqueous solvent & the polar region are arranged to maximize their interaction with the solvent (in an amphophilic compounds)

Question 16

Micelles

Answer 16

Are the stable structures of amphipathic compounds in water

Question 17

Noncovalent interactions

Answer 17

Are hydrogen bonds, ionic bonds, hydrophobic &van der waals interactions (weaker than covalent bonds)

Question 18

__________ are crucial to macromolecular structure & function

Answer 18

Weak interactions

Question 19

Interactions driven by the ______________ are also much weaker than convalent bonds

Answer 19

Hydrophobic effect

Question 20

Hydrophobic interactions

Answer 20

Forces that hold nonpolar regions of the molecules together

Question 21

______________ effect the colligative properties of aqueous solutions

Answer 21

Solutes

Question 22

Water tends to move from ________ to ______ concentrations

Answer 22

High to low

Question 23

When water molecules move from high to low concentrations they produce _____________

Answer 23

Osmotic pressure

Question 24

Osmotic pressure

Answer 24

Is the force needed to resist water movement

Question 25

Osmotic pressure equation:

Answer 25

∏= icRT

Question 26

Osmosis

Answer 26

Water movement across a semipermeable membrane driven by difference in osmotic pressure

Question 27

Isotonic solution

Answer 27

When the solution of osmolarity is equal to the outside of the cell (doesnt gain or lose water)

Question 28

Hypertonic solution

Answer 28

Higher osmolarity than the outside of the cell, the cell shrinks as water moves out

Question 29

Hypotonic solution

Answer 29

Lower osmolarity than the outside of the cell, the cell swells as water moves in

Question 30

Osmotic lysis

Answer 30

Bursting of a cell

Question 31

The ionization of water is expressed by an \_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 31

Equilibrium constant

Question 32

K_w is what

Answer 32

The ion product of water at 25 Celius

Question 33

At 25 Celius K_w value is what ?

Answer 33

1 x 10^-14 M²

Question 34

Neutral pH

Answer 34

When there are equal concentrations of H⁺ & OH^-

Question 35

pH equation is what?

Answer 35

pH= -log{[H⁺] (when pH is greater than 7 its basic & when its lower than 7 its acidic)

Question 36

When pH is below 7.4 its called ________ & when its above 7.4 its called \_\_\_\_\_\_\_\_

Answer 36

acidosis, alkalosis

Question 37

\_\_\_\_\_\_\_ are proton donors & ________ are proton acceptors

Answer 37

Acids, Bases

Question 38

What is the pKa equation?

Answer 38

pKa = -log Ka (the stronger the acid the lower the pKa)

Question 39

\_\_\_\_\_\_\_\_\_ reveal the pKa of a weak acid

Answer 39

Titrations curves

Question 40

A tritration curve is pH on the _____ axis & base added (usually NaOH) on the _____ axis (it shows the pKa of a weak acid)

Answer 40

y, x

Question 41

\_\_\_\_\_\_\_\_\_ are mixtures of weak acids & their conjugated bases

Answer 41

Buffers

Question 42

Buffers

Answer 42

Are aqueous systems that tend to resist changes in pH when small amounts of acid (H⁺) or base (OH^-) are added

Question 43

The midpoint of the titration curve (the pH value) & 1 pH unit out is the ____________ region

Answer 43

Buffering

Question 44

During the buffering region whether H⁺ or OH^- is added the pH barely \_\_\_\_\_\_\_

Answer 44

Change (stays the same basically)

Question 45

The _________________ equations relates pH, pKa, & buffer concentration

Answer 45

Henderson-Hasselbalch equation

Question 46

What is the Henderson-Hasselbalch equation?

Answer 46

pH=pKa + log [H⁺]/[HA]

Question 47

The pKa of a weak acid is equal to the _____ of the solution at the midpoint of a titrations curve

Answer 47

pH

Question 48

Weak acid or bases buffer cells & tissues against _____ change

Answer 48

pH

Question 49

The two important biological buffers are the ____________ & ____________ systems

Answer 49

Phosphate & bicarbonate systems

Question 50

The phosphate system act in the _______ of the cell consist of H₂PO₄^- as proton donor & H₂PO₄^2- as proton acceptor

Answer 50

Cytoplasm

Question 51

The phosphate buffer system pKa & pH is ________ & resist pH changes between 5.9 & 7.9

Answer 51

6.86

Question 52

Blood plasma is buffered in part by the ________ system which has carbonic acids HCO₃^- (Proton donor) & bicarbonate (HCO^-) (as proton acceptor)

Answer 52

Bicarbonate

Question 53

\_\_\_\_\_\_\_\_\_\_\_\_ buffer system is an effective buffer when the pH = 7.4

Answer 53

Bicarbonate

Question 54

H₂CO₃ pKa at 37 Celius is what?

Answer 54

3.57

Question 55

Condensations reactions

Answer 55

Water is eliminated

Question 56

Hydrolysis reactions

Answer 56

Cleavage accompanied by the addition of the elements of water

Question 57

Hydrolases

Answer 57

Hydrolysis reaction catalyze by enzymes (are exergonic & they produce two molecules from one)