Lecture 3: Water And Organic Molecules - Learning Objectives: Chapter 2.3-2.4

Question 1

Identify and Describe the properties of water that make it indispensable to
life on earth.

Answer 1

• high specific heat (resistant to temperature change)
• good solvent
• pH of 7
• cells are 70-95% water

Question 2

Describe the interaction between the atoms of a single molecule of water, and amongst water molecules.

Answer 2

• water is polar. Oxygen has partial negative, hydrogen has partial positive.
• water molecule contains polar covalent bonds,while many water molecules interact with hydrogen bonding.

Question 3

Correlate water’s high specific heat with its ability to stabilize temperature fluctuations.

Answer 3

Water:
- absorbs heat from air that is warmer
- releases stored heat to air that is cooler
- absorbs/releases a large amount of heat with only a slight change in its own temperature

• ability to stabilize temp fluctuations is a result of high specific heat.
• this is a result of hydrogen bonding.

Question 4

Define solution, solute, solvent, aqueous solution.

Answer 4

A solution is a liquid that is a homogeneous mixture of substances.

A solvent is the dissolving agent of a solution.

The solute is the substance that is dissolved.

An aqueous solution is one in which water is the solvent.

Question 5

Relevance of waters high specific heat.

Answer 5

1. Stabilizes ocean temperatures.
2. Limits temperature fluctuations on land and in water that remit life.
3. Organisms, which are primarily made of water can resist changes in their own temperature.

Question 6

Differentiate between hydrophilic and hydrophobic substances.

Answer 6

Hydrophilic - water loving

Hydrophobic - water repelling

Question 7

Correlate changes in hydrogen ion concentration (H+) with pH.

Answer 7

ACID:
Increases [H+]
- reduces pH
- pH<7:acidic

BASE:
Reduces [H+]
- increases pH
- pH > 7: basic

Question 8

Describe the bonding properties of Carbon that relate to its structural diversity.

Answer 8

• A carbon atom behaves as if it has four unpaired
  electrons.
• Forms covalent bonds
• forms a tetrahedron when covalently bonded to 4 other atoms.
• carbon atoms ca link with
  one another to form long
  chains that can be branched
  or a ring structure.
• When Carbons share 2 pairs of e-, a double bond is formed.

Question 9

Define an isomer.

Answer 9

Isomers are molecules with the same chemical formula but different arrangement.