Chemistry Study Guide- Test 4
Chemistry Study Guide- Test 4 ch 1213
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Popular in Chemistry
This 7 page Study Guide was uploaded by Madison Greer on Thursday April 21, 2016. The Study Guide belongs to ch 1213 at Mississippi State University taught by Erin Dornshuld in Summer 2015. Since its upload, it has received 88 views. For similar materials see Chemistry 1 in Chemistry at Mississippi State University.
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Date Created: 04/21/16
• When chemical reactions occur, there is a change in energy. • system- the speciﬁc part of the universe that is of interest to us and is usually deﬁned as the substances involved in chemical and physical changes • surroundings- everything that isn't the system joule- kg m / s 2 • • universe= system+surroundings • thermal energy- the energy that comes from heat • heat- the transfer of thermal energy between two bodies that are different temperatures • thermochemistry- the study of the heat (transfer of thermal energy) associated with chemical reactions • endothermic- heat is supplied to the system; energy ﬂows into the system • exothermic- heat is given off by the system; energy ﬂows out of the system • thermodynamics- the scientiﬁc study of the interconversion of heat and other kinds of energy • open system- can exchange mass and energy with its surroundings • closed system- can transfer energy but not mass to the surroundings • isolated system- cannot exchange either mass or energy with the surroundings • state of the system- the values of all relevant macroscopic properties such as composition, energy, temperature, pressure, and volume • state functions- properties that are determined by the state of the system regardless of how the condition was achieved • ΔT- change in temperature • ﬁrst law of thermodynamics- states that energy can be converted from one form to another, but it can never be created or destroyed • internal energy (ΔU)- ΔU= U ﬁnal- Uinitial • internal energy has two components • kinetic energy- comes from the motions of particles (electrons, nucleus, molecule, etc.) • potential energy- comes from the repulsive/attractive interactions between the particles • ΔU sys+ ΔU surr 0 • ΔU sys= -ΔU surr • Work is NOT a state function. • q- heat released or absorbed by system • w- work done on the system or done by the system • q- positive for an endothermic process and negative for exothermic process • w- positive for work done on the system and negative for work done by the system • KNOW HOW TO DETERMINE AMOUNT OF WORK DONE • pressure-volume work- work done by a constant-pressure process • work= PΔV • q is NOT a state function but q ISv • enthalpy- H • enthalpy- H= U+PV • U- internal energy • P- pressure V- volume • • change in enthalpy- ΔH • qp= ΔH • q is NOT a state function but q Ip • enthalpy of reaction- the difference between the enthalpies of the products and the reactants • thermochemical equations- the chemical equations that show the enthalpy changes as well as the mass relationships Guidelines for writing, interpreting, and manipulating thermochemical equations A + B —> C ΔH = 3.0 kJ/mol 2A + 2B —> 2C ΔH = 6.0 kJ/mol C —> A + B ΔH= -3.0 kJ/mol • calorimetry- the measurement of heat ﬂow (energy changes) • speciﬁc heat (s)- the amount of heat required to raise the temperature of 1 g of the substance by 1 degree Celsius • heat capacity (C)- the amount of heat required to raise the temperature of a object by 1 degree Celsius • speciﬁc heat of water- 4.184 J/ g C • qp- constant pressure • qp= ΔH • qv- constant volume • qv= ΔU • KNOW HOW TO FIND q, s, m, or ΔT. • KNOW HOW TO DO BOMB CALORIMETRY • KNOW HOW TO DO HESS’S LAW o • standard enthalpy of formation (ΔH )- fhe heat change that results when 1 mole of a compound is formed from its constituent elements in the standard state at sea level • KNOW HOW TO CALCULATE STANDARD ENTHALPY OF FORMATION FOR A REACTION o • standard conditions- 1 atm at 25 C • standard enthalpy of reaction (ΔH rxn)- the enthalpy of reaction carried out under standard conditions • bond enthalpy- the enthalpy change associated with breaking a particular bond in 1 mole of gaseous molecules • KNOW HOW TO CALCULATE BOND ENTHALPY • Light gas particles move faster than heavy gas particles, which move slower. • KNOW THE 4 BASIC ASSUMPTIONS OF KINETIC MOLECULAR THEORY • root mean square (rms) speed (u rms)- the speed of a gas molecule with the average kinetic energy in a gas molecule • diffusion- the mixing of gases due to random motion and frequent collisions • effusion- the escape of gas molecules from a container to a region of vacuum • Graham’s law- states that the rate of diffusion or effusion of a gas is inversely proportional to the square root of its molar mass • pressure- a force applied per unit area • newton (N)- the SI unit of force • pascal (Pa)- the SI unit of pressure • barometer- an instrument that is used to measure atmospheric pressure • standard atmospheric pressure- 1 atm • Boyle’s law- states that the pressure of a ﬁxed amount of gas at a constant temperature is inversely proportional to the volume of the gas • Charles’ and Gay-Lussac’s law- states that the volume of a gas maintained at constant pressure is directly proportional to the absolute temperature of the gas • Avogadro’s law- states that the volume of a sample of gas is directly proportional to the number of moles in the sample at constant temperature and pressure • combined gas law- relates the properties of pressure, temperature, volume, and number of particles into one equation • ideal gas equation- describes the relationship among the four variables P, V, n, and T • ideal gas- a hypothetical sample of gas where the particles are assumed to have zero interaction with each other • gas constant (R)- the proportionality constant and its value and units depend on the units in which P and V are expressed • standard temperature and pressure • pressure- 1 atm o • temperature- 0 C (273.15 K) • van der Waals equation- useful for gases that do not behave ideally • compressibility factor- Z • Dalton’s law of partial pressures- states that the total pressure exerted by a gas mixture is the sum of the partial pressures exerted by each component of the mixture • lattice energy- the energy change associated with converting 1 mole of ionic solid to its constituent ions in the gas phase • Born-Haber cycle- the method of determining lattice energy KNOWW THESEEEQQUATIONSSANND WHHEN AND HOOW TO USEETHHEM urms √3RT/M root mean square (rms) speedrms A B u rmsu rms √M BM A Graham’s law rate is proportional to 1/√M barometer equation P=hdg Boyle’s law P 1 1P 2 2 Charles’ and Gay-Lussac’s law V1/T1=V2/T2 Avogadro’s law V1/n1=V2/n2 KNOWW THESE EQUAATONNSANND WHEENANNDHOOW TO USE THEM combined gas law P 1 1n1 1= P2V 2n2 2 ideal gas equaiton PV=nRT ideal gas equation (with density) d=PM/RT compressibility factor Z=PV/RT Dalton’s law P total Pi mole fractions Xi nintotal
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