Water

• Covers more than 75% of the Earth’s surface, and makes up 70-95% of most organisms

• Most abundant compound in organisms• One of the few naturally occurring compounds that is a liquid• Water is the only common molecule that can be a solid, a

liquid, or a gas according to the environmental temperature• Facilitates reactions both outside and within living systems• Water is perhaps the most important compound in living

organisms. Most life processes can occur only when molecules and ions are free to move and collide with one another and this condition exists when they are dissolved in water

John 7: 37-38

• “ On the last and greatest day of the Feast, Jesus stood and said in a loud voice, ‘ If anyone is thirsty, let him come to me and drink. Whoever believes in me, as the scripture has said, streams of living water will flow from within him.”

1Peter 3:21

• “………and this water symbolizes baptism that now saves you also-not the removal of dirt from the body but the pledge of a good conscience toward God. It saves you by the resurrection of Jesus Christ who has gone into heaven and is at God’s right- with angels, authorities and powers in submission to him.”

Ephesians 5:26

• “Husbands, love your wives, just as Christ loved the church and gave himself up for her to make her holy, cleansing her by the washing with water through the word, and to present her to himself as a radiant church, without stain or wrinkle or any other blemish, but holy and blameless.”

Revelation 21:6

• “He said to me: ‘It is done. I am the Alpha and the Omega, the Beginning and the End. To him who is thirsty I will give to drink without cost from the spring of the water of life.’”

Water is Polar

• when atoms in a covalent bond do not share the electrons equally, they form a polar bond

• A polar molecule is a molecule with an unequal distribution of charge; that is, each molecule has a positive end and a negative end. Water is a polar molecule.

Water is polar

• Polar water molecules attract ions as well as other polar molecules. Because of this attraction, water can dissolve many ionic compounds, such as salt, and many other polar molecules, such as sugar

• “Universal Solvent” because of its ability to dissolve a wide range of materials

Universal solvent

Water the universal solvent

Solvent

• Solvent- A solvent (from the Latin solvere, "loosen") is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature.

Solute

• A solute is a substance dissolved in another substance, forming a solution ( for instance; dissolved sugar in water )

Water as a solvent

• Water is a good solvent due to its polarity. The solvent properties of water are vital in biology, because biochemical reactions take place only within aqueous solutions. In addition, water is used to transport biological molecules in the cytoplasm and blood.

Hydrophilic and Hydrophobic

• Substances that will mix well and dissolve in water are known as hydrophilic (“water loving”)

• Substances that do not mix well with water are known as hydrophobic (“water fearing”)

• The ability of a substance to dissolve in water is determined by whether or not the substance can match or better the strong attractive forces that water molecules generate between other water molecules

• If the forces are not overcome, the molecules are pushed out from the water and do not dissolve.

• When an ionic or polar substance enters water, it is surrounded by water molecules. The relatively small size of water molecules typically allows many water molecules to surround one molecule of solute. The partially negative dipoles of the water are attracted to positively charged components of the solute and vice versa for the positive dipoles.

• In general, ionic and polar substances such as acids, alcohols, and salts are easily soluble in water

• Nonpolar substances such as fats and oils are not easily soluble in water. Nonpolar molecules stay together in water because it is energetically more favorable for the water molecules to hydrogen bond to each other than to engage in interactions with other molecules.

• Water molecules also attract other water molecules. The positively charged hydrogen atoms of one water molecule attract the negatively charged oxygen atoms of another water molecule.

• This attraction of opposite charges between hydrogen and oxygen forms a weak bond called a hydrogen bond

Demonstration #1

• Fill a clean bowl with water• See how many paper clips you can float on top

of the water• Once several clips are floating, add a couple

drops of dish soap to the water and watch what happens

• Try floating a paper clip now that the water has soap in it. What happens?

Use your notes to answer the following questions #1

• #1 Why are the water molecules attracted to each other and how does this attraction enable you to float a paperclip on the surface of the water?

• #2 This is a phospholipid. From Your notes, how does a phospholipid change the ability to float the paper clips? (use the terms surface tension, lipid, polar, and non-polar in your answer)

cohesion

• Water molecules are cohesive. Water flows freely yet water molecules do not break apart. They cling together because of hydrogen bonding.

• “The ability of water molecules to stick to themselves due to the hydrogen bonds”

• Also known as SURFACE TENSION

Cohesion definition

• cohesion-Cohesion (n. lat. cohaerere "stick or stay together") or cohesive attraction or cohesive force is the action or property of like molecules sticking together, being mutually attractive. This is an intrinsic property of a substance that is caused by the shape and structure of its molecules which makes the distribution of orbiting electrons irregular when molecules get close to one another, creating electrical attraction that can maintain a macroscopic structure such as a water drop.

Cohesion

Jesus Christ Lizard

• http://www.youtube.com/watch?v=AQ6OtKywyD8

• Matthew 14: 22-32

Demonstration #2

• Water forms very cohesive bonds that can sometimes defy gravity.

• You will predict how many drops of water will fit on a penny before it spills over

• Obtain a new, dry penny. Rub detergent on it. Repeat the process of dropping water on the surface. Will it hold more or less drops?

• Amphipathic- being polar (charged) at one end and nonpolar at the other. This is a disruptive effect upon the cohesiveness of water

Use your notes to answer this question

#2 Explain this demonstration (water and water plus detergent) in terms of cohesion and the polarity of water

Demonstration #3

• Add equal parts of oil and water to a graduated cylinder

• Add a few drops of dye to the graduated cylinder

• Mix the contents and observe the results

Use your notes to answer this question

#3 Explain the results of this demonstration. Your explanation should involve POLARITY, POLAR, NON-POLAR molecules, SOLUTION, and HYDROGEN BONDING.

adhesion

• Water also adheres to surfaces, particularly polar surfaces

• Therefore, water can fill a tubular vessel and still flow so that dissolved and suspended molecules are evenly distributed throughout a system

Adhesion definition

• Adhesion is any attraction process between dissimilar molecular species that can potentially bring them in close contact. By contrast, cohesion takes place between similar molecules

Adhesion

•Due to cohesion and adhesion, water is an excellent transport system both outside of and within living organisms.

Capillary action

• Capillary action- how plants get water from the ground. Capillary action and the tension on the water’s surface, which is also a result or polarity, play major roles in getting water from soil to the tops of even the tallest trees

Capillary action

Temperature and water

• The temperature of liquid water rises and falls more slowly than that of most other liquids

• The many hydrogen bonds that link water molecules help water absorb heat without a great change in temperature

• Because water hold heat so effectively, its temperature falls more slowly

• Water protects organisms from rapid temperature changes and helps them maintain their normal internal temperature- therefore homeostasis

Water has a high heat of vaporization

• Hydrogen bonds must be broken to change water to steam; this accounts for the very large amount of heat needed for evaporation

• This property of water helps moderate the earth’s temperature so that it permits the continuance of life

• It also gives animals in a hot environment an efficient way to release excess body heat. When an animal sweats, body heat is used to vaporize the sweat, thus cooling the animal

Frozen water is less dense than liquid water

• Water is one of the few substances that expands when it freezes

• As water cools, the molecules come closer together. This makes ice less dense than water, which is why ice floats on liquid water.

• When a body of water freezes on the surface, the ice acts as an insulator to prevent the water below it from freezing which protects many aquatic organisms so that they can survive the winter

Problem solving lab 6.2 pg 154

•Complete and turn in for a grade

Diffusion page 154

•Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration

• Diffusion results because of the random movement of particles

• This is known as Brownian motion• Brownian motion- the random motion of

atoms and molecules that is characteristic of gases, liquids and some solids

What affects the rate of diffusion?

•1. concentration•2. temperature•3. pressure

Concentration affecting diffusion

• Primary controlling factor• The more concentrated the

substances, the more rapidly diffusion occurs because there are more collision between the particles of the substances.

Temperature and Pressure and Diffusion

• Increase temperature increases energy and will cause more rapid particle motion- therefore increasing the rate of diffusion• Increasing pressure will accelerate

particle motion and therefore diffusion

The results of diffusion

• Dynamic equilibrium- continuous movement of particles but no overall concentration change