1 Chapter 3 Water and the Fitness of the Environment

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Figure 3.1 AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

H O wants to fill this HH Covalent Bonding Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

5 (a) (b) Name (molecular formula) Electron- shell diagram Structural formula Space- filling model Hydrogen (H 2 ). Two hydrogen atoms can form a single bond. Oxygen (O 2 ). Two oxygen atoms share two pairs of electrons to form a double bond. HH O O Figure 2.11 A, B AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

6 Name (molecular formula) Electron- shell diagram Structural formula Space- filling model (c) Methane (CH 4 ). Four hydrogen atoms can satisfy the valence of one carbon atom, forming methane. Water (H 2 O). Two hydrogen atoms and one oxygen atom are joined by covalent bonds to produce a molecule of water. (d) H O H HH H H C Figure 2.11 C, D AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Polar Covalent Bond AIM: How do atoms interact with each other? Chapter 3 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Non-polar covalent bond AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Hydrogen Bonds AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

10 ◦ Reinforce the shapes of large molecules ◦ Help molecules adhere to each other Plasma membrane are stabilized by the additive affect of Van der Waals interactions between non-polar fatty acid tails of phospholipids. H bonds The two strands of a DNA molecule are held together tightly by the additive affect of many, many weak Hydrogen Bonds AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

ions Cation vs Anion The sodium and chloride ions are now attracted to each other and form an ionic bond. ionic bond = bond between two oppositely charged ions Ionic Bond AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

12

Fig. 2-UN11 AIM: How do atoms interact with each other? Chapter 2 – The Chemical Context of Life

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Water-conducting cells Adhesion Cohesion 150 µm Direction of water movement AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment How is water transported against gravity in plants?

Water-conducting cells Adhesion Cohesion 150 µm Direction of water movement AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment How is water transported against gravity in plants?

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

A measure of how well a substance resists change in temperatures 1 kcal = 1,000 calories; amount of heat needed to raise the temp of 1kg of water AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment Specific heat of iron: 0.1 cal/g/ o C

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment Water, because of it H-bonding (cohesive nature) has a very high specific heat relative to other molecules. It is difficult to get the water molecules to vibrate since they are all sticking to each other. The H-bonds need to be broken. Think about this analogy: is easy to push a single student and get them moving fast, but if you all hold hands, it becomes more difficult as I would need to break those bonds. Helps organisms resist change in temperature!!

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Water has a relatively high heat of vaporization because the hydrogen bonds of the water that must be overcome in order for evaporation to occur AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Liquid water Hydrogen bonds constantly break and re-form Ice Hydrogen bonds are stable Hydrogen bond AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Solvent: the dissolving agent in a solution Solute: the substance being dissolved Solution: a homogeneous mixture Aqueous solution: water is the solvent AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

“Cage” of water molecules surrounding each dissolved substance Hydration shell AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

This oxygen is attracted to a slight positive charge on the lysozyme molecule. This oxygen is attracted to a slight negative charge on the lysozyme molecule. (a) Lysozyme molecule in a nonaqueous environment (b) Lysozyme molecule (purple) in an aqueous environment such as tears or saliva (c) Ionic and polar regions on the protein’s Surface attract water molecules. ++ –– Figure 3.7 AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

Rule of thumb: LIKE DISSOLVES LIKE AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

AIM: Why is water important to life? Chapter 3 – Water and the Fitness of the Environment

33 How would you make a 0.5-molar (0.5 M) solution of sodium chloride (NaCl)? 1.Find moles 2.Convert moles to grams (factor label method) 3.Add enough water to make 1 L Molarity = moles of solute liter of solution Moles = M * L 1. Moles = 0.5 M * 1 L = 0.5 moles moles * _________g 1 mole Remember 1 mole = formula mass 58.5 = 29.3 g of NaCl and fill with water to 1 L

34 How many grams of acetic acid (C 2 H 4 O 2 ) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? 1.Find moles 2.Convert moles to grams (factor label method) Molarity = moles of solute liter of solution Moles = M * L 1. Moles = 0.1 M * 10 L = 1 mole 2.1 mole * _________g 1 mole Remember 1 mole = formula mass = 60 g of acetic acid 60

35 What is the molarity of a solution made by dissolving 2.5 g of NaCl in enough water to make 125 ml of solution? 1.Convert grams to moles 2.Find molarity Molarity = moles of solute liter of solution g * 1 mole g Remember 1 mole = formula mass 58.5 = moles 2. Molarity = moles L Molarity = 0.34 M NaCl

36

AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment H 2 O H + + OH - Hydrogen ion (aka… a proton) Hydroxide ion The oxygen atom is more electronegative than the hydrogens and pulls the shared electrons away from them, which can cause one of the hydrogens (a proton) to fall off.

H Hydronium ion (H 3 O + ) H Hydroxide ion (OH – ) H H H H H H + – + Figure on p. 53 of water dissociating H 2 O H + + OH - AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment It will transfer from one water to another to form H 3 O + This change can significantly change the pH of an aqueous solution

pH stands for potential hydrogen and measures the hydrogen ion concentration in an aqueous solution Logarithmic scale from 0 to 14 Difference of 10X in hydrogen ion concentration between any two pH values AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment What if the pH is 10 X higher?

How many times more acidic is lemon juice than urine? 10,000X more acidic

How many times more basic is milk of magnesia (pH 11) compared to seawater (pH 8)? 1000X more basic

Increasingly Acidic [H + ] > [OH – ] Increasingly Basic [H + ] < [OH – ] Neutral [H + ] = [OH – ] Oven cleaner pH Scale Battery acid Digestive (stomach) juice, lemon juice Vinegar, beer, wine, cola Tomato juice Black coffee Rainwater Urine Pure water Human blood Seawater Milk of magnesia Household ammonia Household bleach Figure 3.8 AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment

1. What does the pH value tell us about the solution? 2. What happens to the pH as the [H + ] increases? 3. If the pH of a solution is increased by three pH units, how has the [H + ] changed? The H + (free proton) concentration [H + ] decreases 1000x lower [H + ]

AIM: How does pH affect living organisms? Chapter 3 – Water and the Fitness of the Environment