Exam 1 - Chapter 3

Question 1

life sustaining properties of water

Answer 1

• cohesive and adhesive nature
• ability to moderate temperature
• expansion upon freezing
• versatility as a solvent

Question 2

cohesive and adhesive nature

Answer 2

• cohesion=attraction between molecules of same type
• adhesion=attraction between different substances
• surface tension=measure of how hard it is to break surface of liquid

Question 3

temperature moderation

Answer 3

water only liquid to be in three different states

Question 4

temperature

Answer 4

measure of average molecular motion

Question 5

specific heat

Answer 5

amount of heat required for 1g of a substance to change its temp by 1C

Question 6

calories

Answer 6

amount of heat needed to raise 1g of water by 1C

Question 7

high spcific heat of water

Answer 7

heat is absorbed to break bonds, heat is released when bonds form

Question 8

heat of vaporaziation

Answer 8

quantity of heat a liquid must absorb for 1g to be converted to gas

Question 9

evaporative cooling

Answer 9

as liquid evaporates its remaining surface cools

Question 10

expansion on freezing

Answer 10

ice is less dense than liquid water, hydrogen bonds in ice are more ordered, molecules are farther apart, bonds are more stable, ice insulates water below

Question 11

versatile solvent

Answer 11

• Solute is dissolved in a solvent >solution
• Solute – a dissolved substance
• Solvent – dissolving agent
• Solution – uniform mixture of solute completely dissolved in solvent
• Aqueous solution – solution where water is the solvent
• Chemical bonds do not form between molecules of solute and solvent
• Hydration shell forms around solute keeping it in solution

Question 12

solute concentrations in aqueous solutions

Answer 12

• molarity (M) = moles/L
• 1 mole = 6.02 x 10^23 particles = molecular mass of substance (g) = formula weight (FW) in grams
• M = moles/L = (g/MW)/L = (g/FW)/L

Question 13

pH and Buffers

Answer 13

• water dissociates into hydroxide ions (OH-) and hydrogen ions (H+)
• numeric definition of pH = -log [H+]
• pH scale is an inverse log ranging from pH 0-14
• [H+][OH-] = 1 x 10-14