Chapter 2: Water as the Solvent of Life Flashcards
1
Q
Approximately what percentage of the cell is made of water?
A
75%
2
Q
Water has an ____ charge distribution
A
unequal
3
Q
What gives water its unique properties?
A
- each water molecule can form up to four hydrogen bonds with other water molecules
4
Q
Water has a high boiling point. Why is this advantageous in some instances?
A
- makes water resist rapid changes in temperature
ex. milk vs water, milk will boil and freeze faster
5
Q
What is water’s shape when solid?
A
tetrahedral
6
Q
How does polarity play a role in water being the solent of life? (4)
A
- unequal charge distribution allows it to dissolve many ionic compounds
- positive regions of water molecules surround negative ions
- negative regions surround positive ions
- holds ions in solution
ex. NaCl easily dissolves into Na+ and Cl- in water
7
Q
Why is water found in mostly liquid state on Earth? (2)
A
- due to strong attraction between water molecules
- high boiling point
8
Q
How does water’s polarity play a role in dissolving/dissociating solutes/ (3)
A
- allows polar substances to dissociate/dissolve
- positive portion of a solute molecule attracted to the neg. oxy, and negative portion is attracted to positive H
- Therefore, salts like NaCl tends to separate into cations and anions
9
Q
Why is water the key to many digestive processes? (2)
A
- large molecules broken down into smaller
- also for synthetic reactions as it is a source for H and O atoms that are incorporated into many organic compounds in living cells
10
Q
How does water’s polarity affect its ability to resist change? (3)
A
- heat absorption by molecules tend to increase kinetic energy and their rate of motion
- With water, heat first breaks H-bonds rather than increasing rate of motion
- thus water does not heat and cool as fast as other liquids
11
Q
How does water’s polarity affect pH? (2)
A
- it facilitates the splitting and joining of hydrogen ions (H+) and hydroxide ions (OH-)
H2O <–> H+ + OH- - it makes these ions available for chemical reactions
12
Q
How is the pH scale measured?
A
- by the concentration of H+ ions in a solution
