Ch 3-Water

Question 1

Prroperties of water that are critical to maintaining life

Answer 1

• Cohesive behavior
• Ability to moderate temperature
• Expansion upon freezing
• Versatility as a solvent

Question 2

Why water is an excellent solvent

Answer 2

It is such a good solvent because its polarity allows it to dissolve both ionic bonds and other polar molecules.

Question 3

Waters Cohesive & Adhesive Properties

Answer 3

• Cohesion
  
  • The tendency for like molecules to stick together
  • Caused by hydrogen bonding
• Adhesion
  
  • The tendency of two kinds of molecules to stick together

Question 4

PH scale

Answer 4

• In any aqueous solution at 25°C, the prodduct of H⁺ and OH^- is constant and can be written as [H⁺][OH^-] = 10^-14
• The pH of a solution is defined by the negative logarithm of H⁺ concentration, written as pH = -log [H⁺]
• For a neutral aqueous solution, [H⁺]is 10^-7, so pH = -(-7) = 7

Question 5

Acids, Bases, & Buffers

Answer 5

• Acids
  
  • a chemical substance that neutalizes alkalis, dissolves some metals, and turns litmus red; typically, a corrosive or sour-tasting liquid of this kind
• Bases
  
  • Either of the nucleotide bases linked by a hydrogen bond on opposite strands of DNA or double-stranded RNA
• Buffer
  
  • A solution that resists a change in pH when acids or bases are added