2.2 Properties of Water LEQ: How does water behave as a solvent? Reading 32.1, 2.3 Activator: connecting concepts –When sugars are broken down to produce usable carbon and energy for cells, a large amount of heat is released. Explain how the water inside a cell helps to keep the cell’s temperature constant. Key terms – solution, pH

2.2 Properties of Water Compounds with a partial or full electric charge can dissolve in water. Solutions: –Solvents dissolve other substances. –Solutes dissolve in a solvent. solution

2.2 Properties of Water Solvent rules: “Like dissolves like.” –Polar solvents dissolve polar solutes –Hydrophilic: “water-loving”

2.2 Properties of Water Nonpolar solvents dissolve nonpolar solutes: –Polar and nonpolar separate –hydrophobic – “water-fearing”

2.2 Properties of Water Water’s unique properties allow it move and store heat in solution. Movement provides thermal energy –Charges create an electric field (think static). –Water molecules ionize!

2.2 Properties of Water Hydrogen bonds are organized into networks. Proton-hopping: –Moves proton through network –Sensitive to acids, bases

2.2 Properties of Water Pure water is a neutral solution: –Water associating and dissociating is proportional –pH of 7.0 (the occasional “hop”) –Low reactivity pure water pH 7

2.2 Properties of Water Some compounds release or accept protons in solution. pH measures conc. of H + in sol’n inversely –acids donate H + in water. –Increases proton-hopping (reactivity) –pH drops as H + increases more acidic stomach acid pH between 1 and 3

2.2 Properties of Water A base removes hydrogen ions from a solution. –Accepts hopping protons, removes others –H + drops –pH greater than 7 bile pH between 8 and 9 more basic

2.2 Properties of Water Summary: The most important thing: –What was the important thing that you learned about water today? -2 nd …. -3 rd ….. Explain the concept of proton-hopping. How does this relate to the concept of pH?