Chem 105a Week 5 Notes
Chem 105a Week 5 Notes CHEM 105A
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This 4 page Class Notes was uploaded by Emma Morrissey on Friday September 23, 2016. The Class Notes belongs to CHEM 105A at University of Southern California taught by Thomas Michael Bertolini in Fall 2016. Since its upload, it has received 25 views. For similar materials see General Chemistry in Chemistry at University of Southern California.
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Date Created: 09/23/16
Chapter 4 Continued 9/19/16 ● Oxidation-Reduction Reactions ○ Oxidation ■ Loss of electrons ○ Reduction ■ Gain of electrons ○ Oxidizing agent ■ Gains electrons, is reduced ○ Reducing agent ■ Loses electrons, is oxidized ○ Oxidation and reduction are always together; one species transfers electrons to another ○ Oxidation is Loss, Reduction Is Gain; OIL RIG ○ Anything that reacts with O2 (except F2) is oxidized (loses electrons), but oxygen is not required for redox to occur ○ Reactions of metals and nonmetals to give ionic compounds are common subclass of redox rxns ● Oxidation state ○ Assigning elements an oxidation state in reaction allows us to trace electron flow during the reaction ○ Except for monatomic ions, oxidation states are not ionic charges ○ Oxidation states are assigned by giving electrons in a bond (for counting purposes) to the more electronegative element ■ Note electronegativity trend ○ Oxidation state rules ■ Free elements have an oxidation state of zero ● Cl2 = 0; F2 = 0 ■ Monatomic ions have oxidation states equal to their charge ● NaCl: Na = +1; Cl = -1 ■ The sum of the oxidation states for all the atoms in a compound is zero ● NaCl: +1 + -1 = 0 ■ The sum of the oxidation states of all the atoms in a polyatomic ion equals the charge of the ion ● NO3-: N=+5, O=-2 ■ Group I metals have an oxidation state of +1 in compound ● NaCl: Na = +1 ■ Group II metals have an oxidation state of +2 in compound ● MgCl2: Mg=+2 ■ In their compounds, nonmetals have the following oxidation states ● F=-1 ● H=+1 ● O=-2 Chapter 5 ● Pressure ○ The force per unit area ○ 1 Pascal (Pa) = 1N/m^2 = 1kg/(ms^2) ○ The torr and atm are the only non-SI units used in this class ● Barometer ○ Used to measure pressure ○ Created in 1643 by Torricelli ○ Inverted tube of Mercury into a dish ○ Mercury stands 760 mm tall at sea level ○ 9/21/16 ● Manometer ○ Measure gas pressure inside a flask relative to atmospheric pressure ○ ● Simple gas laws ○ PV=k ■ P1V1=P2V2 ■ Gas pressure is a result of gas particles striking their container. As pressure increases, the particles collide more frequently with the walls ○ V=bT ■ At constant pressure, volume and temp are directly proportional ■ Gases expand when heated ■ Use Kelvins ■ V1T2=V2T1 ○ V=an ■ ○ An ideal gas strictly obeys the ideal gas law ○ Real gases best obey the ideal gas law at low pressure and high temperature ○ In theory, PV=Constant 9/23/16 ● Ideal Gas Law ○ PV=nRT ○ Universal Gas Constant R= .08206 Latm/molK ○ Generally, when solving ideal gas problems, identify which values are constant and then establish a relationship between the variables