Outline of Last LectureOutline of Current LectureCurrent LectureI. Watera. Propertiesb. Key termsc. Bondsd. Solutionsi. Molesii. Acids & Bases1. The pH scaleBIO SCI 150 1st Edition Lecture 2Outline of Last Lecture I. Introductiona. What is Biology?b. Living systemsi. Classificationc. Approaches in Biologyd. Major theoriesII. Atoms/Chemistrya. What is an atom?b. How atoms interact…Outline of Current Lecture I. Watera. Propertiesb. Key termsc. Bondsd. Solutionsi. Molesii. Acids & Bases1. The pH scaleCurrent LectureI. Water- Essential for life- Major component of planet surface- Major component of living cells 70-95%a. Properties- H2O- Polar (H δ+, O δ-)- Found in most living things- Because of hydrogen bonding, water has a high specific heat.- Water stabilizes air temperature by storing and releasing heat - Because of hydrogen bonding water has a high heat of vaporization.- At different states…o At high temperatures the hydrogen bonds break and molecules are free as gaso At moderate temperatures hydrogen bonds break and reform, giving a liquido At low temperatures multiple hydrogen bonds produce solid iceb. Key terms- Kinetic Energy – movement of atoms- Temperature – intensity of heat (average)- Amount of Heat – temperature + mass- Specific Heat – amount of heat to raise 1g 1 degree- Hydrogen Bonds Produce:o Cohesion - molecules bound to like molecules, forms streamso Adhesion - molecules bound to different substance produces wettingo Surface tension - hydrogen bonding to each other along surface and below- Celsius- 0° freeze 37° human 100 boil- Calorie- amount of heat energy needed to raise temperature of lg of water 1°C- kilocalorie amount of heat energy needed to raise temp of 1kg water, or liter 1° C- Heat of vaporization - amount of heat a liquid must absorb for lg to be converted to gasc. Bonds- Water absorbs energy to break Hydrogen bonds.- Energy is released when Hydrogen bonds form.- Water freezes when all H bonds form.- This makes a solid and expands the structure, since the rigid hydrogen bonds do not allow molecules to move closer to each other- Water gives off energy as it freezes- Water absorbs energy as it meltsd. Solutions- Polar nature of water makes it a good solvent for polar or ionic solids like salt.o Solution- homogeneous mixture of 2 or more substanceso Solvent- liquid in solutiono Solute- dissolved substance- Polar nature of determines its behavior with other substances.o Hydrophilic likes water dissolve or absorb ionic, polaro Hydrophobic repels water, will not dissolve in water Nonpolar, nonionic, oil, wax “a ducks back”i. MolesMolemolecular weight number (M) Given in grams not daltons1 mole of anything contains 6.02 x 1O23 molecules (“Avogadro’s number”)ii. Acids & BasesIf a hydrogen atom leaves one water molecule, but leaves its electron behind, the water molecule gains a negative charge and is called a hydroxide ion.The hydrogen atom without its electron is a hydrogen ion, a single proton witha charge of +1. If another water molecule acquires this proton it becomes ahydronium ion with a charge of +1. Water exists as equilibrium.- Definition - Substances that cause an unbalance in the ration of hydrogen and hydroxide ions are called acid or baseo Acid increases H+ concentrationo Base increases OH- concentration, decreases H+ concentration- A buffer will maintain a balance by shifting the direction if there is a changein H+ concentration1. The pH scale- The concentration of H+ ions in a solution can be determined using pH.- pH = - log of H+ concentration- Low pH = acid = more hydrogen ions- High pH = base = less hydrogen ions- Increase of 1 pH unit = 10 x increase in H- Increase of 2 pH units = 100 x increase in
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