2.2 Properties of Water

GuidanceStudents should know at least one example of a benefit to living organisms of each property of water.Transparency of water and max density at 4⁰C do not need to be included.Comparison of the thermal properties of water and methane assists in the understanding of the significance of hydrogen bonding in water.

UNDERSTANDINGS

Water molecules are polar and hydrogen bonds form between them.

Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal, and solvent properties of water.

Substances can be hydrophobic or hydrophilic.

APPLICATIONS/SKILLS

A: Comparison of the thermal properties of water with those of methane.

A: Use of water as a coolant in sweat.

A: Modes of transport of glucose, amino acids, cholesterol, fats, oxygen, and sodium chloride in blood in relation to their solubility in water.

Structure of water moleculesPolar covalent bonds Non-polar covalent bondsVs.

http://2.bp.blogspot.com/-SARicXRpPwQ/TZ2hliIzheI/AAAAAAAAAHY/e_7m-vBkYtQ/s320/Methane+Molecule.JPG

Cohesive properties Water molecules sticking to each other

◦ Water droplets◦ Surface tension◦ Capillary action

https://tse4.mm.bing.net/th?id=OIP.Mfa289671d67f3440bb445e87467c0362H0&pid=15.1&P=0&w=284&h=160http://1.bp.blogspot.com/_MM5U2yzlyAY/TNNhkbjOmoI/AAAAAAAAAMA/LUMCiJhtoMk/s1600/water+strider.jpg

Adhesive properties

http://upload.wikimedia.org/wikipedia/commons/1/1a/Water_Droplet_On_Leaf.jpghttp://www.stonemtg.com.au/images/Basalt1.jpg

Water molecules sticking to other substances

Thermal propertiesHigh specific heat High heat of vaporization

Solvent properties Can dissolve other polar molecules

Solution Location Reaction(s)

Cytoplasm Inside cells, outside of organelles

Glycolysis, protein synthesis

Nucleoplasm Inside nuclear membranes DNA replication, transcription

Stroma Inside chloroplasts Light-dependent reactions of photosynthesis

Blood plasma Arteries, veins, capillaries Transport of gases

Hydrophilic substances “Water loving”

Biochemically important substances contain functional groups that result in polarity

Ex: Glucose, phosphate containing heads of phospholipids

http://harvardforest.fas.harvard.edu/sites/harvardforest.fas.harvard.edu/files/leaves/glucose_molecule.jpg https://romanmd.files.wordpress.com/2010/06/membrane_f11.jpg

Hydrophobic substances “Water fearing”

Non-polar substances

Hydrocarbons

https://romanmd.files.wordpress.com/2010/06/membrane_f11.jpg

http://www.earthtimes.org/newsimage/molecule_methane_275.jpg

Differential polarity Have polar and non-polar regions

Ex: Proteins

http://classconnection.s3.amazonaws.com/338/flashcards/2335338/jpg/types_of_amino_acids1354072786482.jpghttp://2012books.lardbucket.org/books/an-introduction-to-nutrition/section_10/f72560b66acc0f46a0012fbf6c75b504.jpg

Nature of scienceProperty Water Methane

Freezing point

Boiling point

Polar or nonpolar?

Polar covalent or nonpolar covalent bonds?Forms hydrogen bonds?

Read “Nature of Science” in 2.2. Fill out the chart regarding certain properties of water and methane. Then differentiate between the thermal properties of these substances.

HomeworkVOCAB

Aqueous solution

Polar covalent bond

Non-polar covalent bond

Dipolarity

Hydrogen bond

Adhesion

Cohesion

Specific heat

Heat of vaporization

Blood plasma

Hydrophilic

Hydrophobic

Hydrocarbon

OTHER

Exercises 4-5

View the items on table 2.4. Compare and contrast the method of transport in an aqueous environment of one polar and one non-polar substance.