Chem 101 Exam 2 Study Guide
Chem 101 Exam 2 Study Guide 101
Popular in Chemistry
Popular in Chemistry
This 5 page Study Guide was uploaded by Satori Le on Sunday October 18, 2015. The Study Guide belongs to 101 at Washington State University taught by Michael Finnegan in Fall 2015. Since its upload, it has received 62 views. For similar materials see Chemistry in Chemistry at Washington State University.
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Date Created: 10/18/15
Density mass per unit volume 0 That s mass divided by volume units are gmL 0 Density is density dependent 9 volume changes in temperature 0 If temperature is not given assume it is 25 degrees C o I A student has 11372 mL of methanol in a measuring cylinder She pours some of the liquid into a beaker leaving 10839 mL in the cylinder The density of methanol is 07866 gmL What is the mass in g of the methanol in the beaker 0 Volume in beaker 11372 10839 533 mL in beaker o 533mL 7866g 1 mL 4192578 g 419 g three sig figs from 533 o I a graduated cylinder has a mass of 75072 g 2 propanol a liquid with a density of 7854 gmL is added The total mass is now 84926 g a small piece of metal is added It sinks to the bottom of the cylinder The total mass is now 140369 g and the volume reading is 1836 mL what is the density of the metal Mass of metal 140369g 84926g 55443g 9 3 points after dec 1836 mL volume of metal 2 propanol Mass of 2 propanol 84926g 75072g 9954g 9 3 points after dec Volume of 2 propanol 9954g 1 mL7854 g 1254673 mL 9 2 dec Volume of metal 1836 mL 1254673 mL 581327 mL 9 2 dec Density of metal 55443 g 591327 mL 9537317 gmL 9 2 dec 954 gmL OOOOOO Temperature is a measure of the average kinetic energy of the particles in a substance 0 The higher the temperature the faster these particles are moving 0 To make particles move faster you must give them energy 0 Energy units 0 calories cal o joules j 0 food calories Cal o if 20 cal of energy are given to 40 g od metal X the temperature goes up by 180 degrees C If 2000 cal of energy are given to 2000 g of metal X how much will the temp go up 2000 cal 4000g 180 2000 cal 2000 g X 1 4000g 180 2000g x X 4000g 180 2000g 360 degrees C 0000 For a given substance energy mass temp change qm delta T a constant Balancing Chemical Equations Examples a solid that forms when two solutions are mixed is called a precipitate To find the products of a precipitation reaction simply have the cations and anions switch partners Problem Equation Balanced Equation Potassium metal reacts with water to form a solution of potassium hydroxide and hydrogen gas KsH20l9 aqH2g 2 Ks2 H20l9 2 KOHaqH2g represents the state sg etc Water is decomposed into hydrogen gas and oxygen gas H20I9 H2g028 2I39I20I92Hzgquot3902g Ethanol burns reacts with C2H60 0289C02g H20g C2H60 302g92C02g oxygen to form carbon 3H20g dioxide and water A solution of iron chloride FeC2aqNaOHaq 9FeOH2NaC FeC2aq2NaOHaq and a solution of sodium hydroxide are mixed 9FeOH2 s2NaCIaq A solution of sodium phosphate and a solution of nickel sulfate are mixed Na3PO4aqNiSO4aq9 NaZSO4Ni3PO42 2Na3PO4aq3NiSO4aQ9 2NaZSO4aqNi3P042S A solution of potassium sulfate is mixed with a solution of copper M acetate KZSO4aqCuC2H3022aq9 KC2H302CuSO4 KZSO4aqCuC2H3022aq9 2 KC2H302aqCuSO4aq Solubility rules this is hierarchical list of rules the first applicable rule supercedes latter rules 1 5 quot N9 P P All sodium potassium lithium and ammonium salts are soluble All nitrates acetates and perchlorates are soluble AgCH3C02 is slightly soluble All silver lead and mercury salts are insoluble Mercery chloride is soluble Mercury II bromide is slightly soluble All chlorides bromides and iodides are soluble All carbonates phosphates sulfides and iodates and oxides are in soluble All hydroxides are insoluble All sulfates are soluble For balancing o Ionic equations dissociate all aqueous ions 0 Net ionic equations remove the spectator ions How to find the oxidation number of atoms in a molecule or polyatomic ion 1 Draw the Iewis structure 2 Oxidation number v w a V the normal number of valence electrons for that atom b W the number of electrons around the atom in the compound or ion Electrons in bonds belong to the more electronegative atom I identify the oxidation number for each element in the following substances 0 NH3 C02V2SO43 KC03 NH3 The oxidation number on N is 5 H N H 8 3 The oxidation number on H is 1 H 0 1 C02 0 C O The ox number on O is 682 The ox number on C is 40 4 V2SO43 O The ox number on V is 3 I The ox number on O is 682 v3 504239 o s o The ox on Sis 60 6 0 239 KCO3 O CI O The ox number on Kis 1 I The ox number on O is 68 2 K GO 0 39 The ox number on CI is 72 5 o What is the mass of one mole of carbon monoxide O O O O O CO C 120 g mol 0 1600 g mol 1216 2801 gmol One mole of CO has mass of 2801 g o Molar mass 0 The mass of one mole of a compound is equal to the sum of the atomic weights of the component atoms 0 What is the molar mass of iron III oxide 0 0 Formula Fe203 25585 gmo 31600 gmol 15970 gmol o Molar mass needs to be provided two digits after decimal point 0 When calculating molar masses use the rules for addition to determine the significant figures Exothermic heat is coming out of reaction Endothermic heat is going into reaction The heat energy released or absorbed by a reaction is called the heat of reaction or the enthalpy change and is represented by the symbol delta H Reactions tend to occur if there is an overall release of energy during the reaction Being exothermic delta H is negative is one way that a reaction can release energy Endothermic reactions have a positive delta H Entropy a measure of the degrees of disorder in a system A change in entropy is designed by the symbol delta S Energy is dispersed as entropy increases How do you judge the change in entropy o Solids lt liquids lt solutions lt gasses I Is AS positive or negative 2 Hg I 02 g a 2 Hg0 5 End product is a s From 3 things to one thing Answer is negative I Is AS positive or negative NaCs 9 Naaq Cquotaq Answer is positive I Is AS positive or negative H2SO4 aq BaOH2 aq 9 2 H20 I BaSO4 5 Negative The total energy all types released or absorbed by the system is called the free energy change and is represented by the symbol delta G The relationship of the change in free energy to the changes in entropy and enthalpy are given by the equation 0 Where T is the temperature in Kelvin K Celsius 27315 If Delta G is negative the reaction is spontaneous 2H2g02g 92H20g Delta S 2121 calK Delta H 11560 kcal o What is the value of delta G for the reaction of hydrogen and oxygen at 25 degrees C 25 27315 29815 K Convert calk to kcal or vice versa 11550 29815 002121 109276 I Spontaneous Sign of delta H Sign of delta S When is delta G negative and the reaction spontaneous Relative temperatures Negative Negative At low temperatures Positive Positive At high temperatures Negative Positive At all temperatures Positive Negative Never
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