LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson © 2011 Pearson Education, Inc. Lectures by Erin Barley Kathleen Fitzpatrick Water and Life Chapter 3

Figure 3.1

Figure 3.2 Hydrogen bond Polar covalent bonds    +  +      +  +  

Figure 3.UN01

Concept 3.2: Four emergent properties of water contribute to Earth’s suitability for life Four of water’s properties that facilitate an environment for life are –Cohesive behavior –Ability to moderate temperature –Expansion upon freezing –Versatility as a solvent © 2011 Pearson Education, Inc.

Figure 3.3 Adhesion Two types of water-conducting cells Cohesion 300  m Direction of water movement

Figure 3.4

Ability to Moderate Temperature The specific heat of a substance is the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1ºC The specific heat of water is 1 cal/g/ºC Water resists changing its temperature because of its high specific heat © 2011 Pearson Education, Inc.

–Heat is absorbed when hydrogen bonds break –Heat is released when hydrogen bonds form © 2011 Pearson Education, Inc.

Figure 3.5 Santa Barbara 73° Los Angeles (Airport) 75° Pacific Ocean 68° Santa Ana 84° Burbank 90° San Bernardino 100° Palm Springs 106° Riverside 96° San Diego 72° 40 miles 70s (°F) 80s 90s 100s

Evaporative Cooling Heat of vaporization is the heat a liquid must absorb for 1 g to be converted to gas As a liquid evaporates, its remaining surface cools, a process called evaporative cooling Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water © 2011 Pearson Education, Inc.

Ability to moderate temperature The unique properties of water: *Density *Structural change-hydrogen bonding *4 degrees Celsius © 2011 Pearson Education, Inc.

Figure 3.6 Hydrogen bond Ice: Hydrogen bonds are stable Liquid water: Hydrogen bonds break and re-form

Water: The Solvent of Life Solution solvent solute An aqueous solution is one in which water is the solvent © 2011 Pearson Education, Inc.

Why is water considered a good solvent? Explain the function of the hydration shell. © 2011 Pearson Education, Inc.

Figure 3.7 Cl  Na                    

Figure 3.8    +  +  

Concept 3.3 Acids and Bases A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other –The hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion (H + )/hydronium ion (H 3 0+ –The molecule that lost the proton is now a hydroxide ion (OH – ) © 2011 Pearson Education, Inc.

Figure 3.UN02 2 H 2 O Hydroxide ion (OH  ) Hydronium ion (H 3 O + ) + 

Acids and Bases An acid is any substance that increases the H + concentration of a solution A base is any substance that reduces the H + concentration of a solution © 2011 Pearson Education, Inc.

The pH Scale In any aqueous solution at 25°C the product of H + and OH – is constant and can be written as The pH of a solution is defined by the negative logarithm of H + concentration, written as © 2011 Pearson Education, Inc. [H + ][OH – ] = 10 –14 pH = –log [H + ] [

Figure 3.10 pH Scale Battery acid Gastric juice, lemon juice Vinegar, wine, cola Beer Tomato juice Black coffee Rainwater Urine Saliva Pure water Human blood, tears Seawater Inside of small intestine Milk of magnesia Household ammonia Household bleach Oven cleaner Basic solution Neutral solution Acidic solution Neutral [H + ] = [OH  ] Increasingly Basic [H + ] < [OH  ] Increasingly Acidic [H + ] > [OH  ] H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ OH  H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H

Buffers The internal pH of most living cells must remain close to pH 7 Buffers are substances that minimize changes in concentrations of H + and OH – in a solution Most buffers consist of an acid-base pair that reversibly combines with H + © 2011 Pearson Education, Inc.

Acidification: A Threat to Water Quality Ocean acidification-results? Role of carbonate? Acid Rain – pH <5.2 (SOX/NOX) © 2011 Pearson Education, Inc.

Figure 3.11 CO 2 CO 2 + H 2 OH 2 CO 3 H + + HCO 3  H + + CO 3 2  HCO 3  CaCO 3 CO 3 2  + Ca 2+ H 2 CO 3