# Test Three Flashcard

 thermodynamics
 study of energy and its transformations
 thermochemistry
 branch of thermodynamics that deals with heat in chemical and physical changes
 system
 part of the universe that is being focused on
 surroundings
 everything (in reason) that is not the system
 internal energy E
 sum of all kinetic and potential energy of each particle in a system
 DE =
 Efinal – Einitial Eproducts – Ereactantsq + w
 a change in energy of the system must be accompanied by
 an equal and opposite change in energy of the surroundings
 releasing energy in a transfer to the surroundings
 Efinal < Einitial so DE<0
 absorbing energy in a transfer from the surroundings
 Efinal > Einitial so DE>0
 q symbolizes
 heat
 heat –
 energy transferred as a result of the difference in temperature between the system and the surroundings
 w represents
 work
 work –
 energy transferred when an object is moved by a force
 energy transferred into the system is
 positive because the system ends up with more energy DE is positive
 energy transferred out of the system is
 negative because the system ends up with less energy DE is negative
 the law of energy conservation
 the 1st law of thermodynamics the total energy of the universe is constant
 joule (J)
 SI unit for energy
 1 J =
 1 kg*m^2/s^2
 calorie (cal)
 quantity of energy needed to raise the temperature of 1 gram of water by 1 *C
 1 cal = _____ J
 4.184 J
 1 J = ___ cal
 0.2390 cal
 the internal energy of a system is called a
 state function
 a state function is dependent on
 the current state of the system, not on the path the system takes to reach that state
 DE depends on
 the difference between the final and initial states, not on how the change takes place
 pressure-volume work (PV work)
 mechanical work done when the volume of the system changes in the presence of eternal pressure
 w =
 -P DV
 H stands for
 enthalpy
 enthalpy-
 internal energy plus the product of the pressure and volume
 H =
 E + PV
 DH =
 DE + P DV
 the change in enthalpy equals
 the heat absorbed or released at constant pressure
 exothermic process
 releases heat and results in the decrease in the enthalpy of the system
 endothermic process
 absorbs heat and results in an increase in the enthalpy of the system
 q =
 c * mass * DT
 heat capacity –
 quantity of heat required to change its temperature by 1 K
 heat capacity =
 q / DT
 specific heat capacity –
 quantity of heat required to change its temperature of 1 gram of the object by 1 K
 c represents
 specific heat capacity
 c =
 q / (mass * DT)
 molar heat capacity –
 quantity of heat required to change its temperature of 1 mole of the substance by 1 K
 C represents
 molar heat capacity
 coffee cup calorimeter
 device that measures the heat transferred at constant pressure
 bomb calorimeter
 device measures the heat released at constant volume
 thermochemical equation
 balanced equation that includes the enthalpy change of the reaction
 Hess’ Law
 the enthalpy change of an overall process is the sum of the enthalpy changes of its individual steps
 DHoverall =
 DH1 + DH2 + DH3…
 standard state for a gas
 at 1 atm and ideal behavior
 standard state for a for a substance in aqueous solution
 1 M concentration
 standard state for a for a pure substance (element or compound)
 the most stable form of the substance at 1 atm and 25*C (298K)
 in a formation equation
 1 mol of a compound forms from its elements
 standard enthalpy of formation
 enthalpy change for the formation equation when all the substances are in their standard states
 the standard enthalpy of reaction is
 the sum of the standard enthalpy of formation of the products minus the sum of the standard enthalpy of formation of the reactants
 examples of fossil fuels
 petroleum, coal and natural gas
 Kinetic Energy
 The energy associated with motion
 Thermal Energy
 Motion of atoms, molecules or ions at the submicroscopic level
 Mechanical Energy
 Motion of a macroscopic objects like a moving basketball or airplane
 Electrical Energy
 Movement of electrons through a conductor
 Acoustic Energy
 The compression and expansion of molecules in the transmission of sound.
 Potential Energy
 The energy associated with an objects position
 types of kinetic energy
 Acoustic EnergyElectrical EnergyMechanical EnergyThermal Energy
 Gravitational Energy
 Energy possessed by a ball held above the floor or by water at the top of a water fall
 Chemical Energy
 Energy stored in fuels or in chemical bonds
 Electrostatic Energy
 The energy associated with the separation of two electrical charges.
 Types of Potential energy
 Gravitational EnergyChemical EnergyElectrostatic Energy
 Law of Conservation of Energy
 Energy can neither be created nor destroyed
 w stands for
 Energy transferred as work to or from the system
 Internal Energy
 The formal name for the quantity E. Internal energy in a chemical system is the sum of PE and KE of the atoms, molecules or ions
 enthalpy is
 equal to the amount of energy transferred as heat at a constant pressure.
 If ?H is negative,
 energy is transferred as heat from the system to the surroundings. Exothermic.
 If ?H is positive,
 energy is transferred as heat from the surroundings to the system. Endothermic.
 The temperature of an object is a measure of
 its ability to transfer energy as heat.
 The higher the temperature,
 the greater the thermal energy of the materials atoms, ions or molecules
 Thermal Equilibrium
 When two objects which were once at different temperatures, reach the same temperature
 Energy transfer as heat will occur spontanesosly from _____ to ______
 the higher temperature material to the lower temperature material
 Calorimetry
 The method by which the energy evolved or required as heat in a chemical of physical process is measured.
 Change of State
 conversion of a substance from one physical state to another, i.e. from a liquid to a solid or from a liquid to a gas
 Heat of Fusion
 The energy transferred as heat that is required to convert a substance from a solid to a liquid
 Heat of Vaporization
 The energy transferred as heat that is required to convert a substance from a liquid to a gas
 The superscript o indicates that
 the reaction has been run at standard conditions.
 Enthalpy changes are specific to
 the reaction being carried out. State of the product produced, is important as are the amounts of products and reactants.
 The enthalpy change depends on the
 number of moles of reaction. That is how many times the as written reaction is carried out.
 Characterized by wavelength and frequency and includes light, microwaves, television and radio signals x-rays, and other forms of radiation
 wavelength
 ambda, ?, the distance between successive crest or high points of a wave. The distance is usually measured in m or nm
 frequency
 nu, ?, refers to the number of waves that pass a given point in some unit of time, usually per second. The unit of frequency, written as s-1 or 1/s is called hertz.
 Clight =
 Clight = 2.99792458 x 108m/s
 Magnetic vector moves _______ to that of the electric vector
 perpendicular
 Nodes:
 where the wave changes from positive to negative
 Plank Assumed
 that the EMR emitted was caused by vibrating atoms called oscilators. And if each oscilator had a frequency, and the emitted radiation had a certain energy, the following eqn could be written.
 Plank’s Constant:
 h = 6.6260693 x 10 -34 J*s
 E=
 h * wavelength
 Photoelectric Effect
 electrons are ejected when light strikes the surface of a metal.
 The energy of each photon is proportional to
 the frequency of the radiation as defined by Planck’s eqn.
 Einstein
 Photoelectric Effect
 Line Emission Spectrum
 The spectrum obtained from passing a beam of light from the excited sample through a prism.
 Balmer Equation
 1/ lambda = R (1/22 – 1/n22), where n is an integer and > 2
 Rydberg Constant
 R = 1.0974 x 107 m-1
 Balmer series.
 The 4 visible lines in the spectrum of hydrogen
 Bohr derived an equation for
 the energy possessed by the single electron in the nth orbit of the H atom
 Bohr Equation
 En = – Rhc / n2
 n defines the
 energies of the allowed orbits in the H atom
 deBroglie
 Proposed that matter which was normally considered a particle, could also exhibit wave properties. Previously for light in the photoelectric effect.
 Bohr Model:
 That both the energy and the location for the electron in the hydrogen atom can be described accurately
 Heisenberg:
 Determined that for an object such as an electron in an atom, it is impossible to determine accurately both its position and its energy.
 Heisenberg Uncertainty Principle:
 any attempt to determine accurately either the location or the energy will leave the other uncertain.
 Schrodinger
 Developed quantum mechanics or wave mechanics. Uses mathematical eqns of wave motion to generate wave functions which are used to describe a electrons in the atom.
 the principle quantum number
 n
 The value of n, is
 the primary factor in determining the energy and size of an orbital.
 For any given atom, the greater the value of n,
 the greater the size of the orbital.
 Orbitals are grouped into _____ .
 subshells
 each subshell is characterized by a different value of ____
 I
 I defines the characteristic
 shapes of the orbitals.
 mf is related to the
 orientation in space of the orbital within a subshell.
 Paramagnetic
 Elements or compounds that have unpaired spins and are attracted to magnets.
 Diamagnetic
 Substances in which all the electrons are paired (with 2 electrons in each pair, having opposite spins) experience a slight repulsion when subjected to a magnet
 electron spin quantum number
 ms
 frequency
 the number of cycles a wave undergoes per second
 energy propagated by electric and magnetic fields that increase and decrease in intensity as they move through space
 visible light, x rays and microwaves are examples of
 wavelength
 the distance between any point on a wave and the corresponding point on the next crest of the wavethe distance the wave travels in one cycle
 speed of light (c) =
 wavelength * frequency
 amplitude
 the height of the crest of wave or the depth of the trough
 the amplitude of a wave is related to the
 types of waves by increasing wavelegth
 types of waves by increasing frequency
 visible light goes from
 400 nm (violet) to 750nm (red)
 refraction
 when a light wave passes through on medium and into another and the speed of the wave changes, making the wave bend in shape
 dispersion
 white light separates into its component colors when it passes through a prism
 diffraction
 when a wave strikes against an object and it bends around it
 when a solid object is heated to about 1000 K and it begins to emit visible light
 the quantum theory was created by
 Planck
 the photon theory was created by
 Einstein
 wavelength and frequency have a _____ relationship
 reciprocal
 line spectrum
 a series of fine lines at specific frequencies separated by black spaces
 Rydberg equation predicts
 the position and wavelength of any line in a given series
 Rydberg equation
 (1 / wavelength) = R ((1 / n1^2) – (1 / n2^2))
 the Hydrogen model atom was created by
 Bohr
 Postulates of Bohr’s Hydrogen Atom Model
 the H atom has only certain energy levels the atom does not radiate energy while in one of its stationary statesthe atoms changes to another stationary state only when absorbing or emitting a photon
 ground state
 when the electron is in the first orbit, is closest to the nucleus and the H atom is in the lowest (first) energy level
 excited state
 if the electron is in any orbit other than the first orbit
 an atomic spectrum (is/ is not) continuous because
 is not; the atom’s energy is not continuous, but rather has only certain states
 an atom changes energy by
 absorbing or emitting a photon of specific energy
 Bohr’s Equation
 DE = Efinal – Einitial = -2.18×10^-18 J ((1/ nfinal^2) – (1/ninitial^2))
 emission spectrum is produced when
 atoms in an excited state emit photons characteristics of an element as they return to lower energy states
 absorption spectrum is produced when
 atoms absorb photons of certain wavelengths and become excited from lower to higher energy states
 a spectrometer is used to measure
 the concentration of a substance in a solution
 absorbance –
 the amount of light of a given wavelength absorbed by a substance
 absorbance is proportional to
 the amount of molecules
 Bohr proposed that
 electrons move in a fixed orbit
 atomic orbit
 mathematical description of the electron’s matter-wave in three dimensions
 n represents
 the principle quantum number
 the principle quantum number indicates
 the relative size of the orbital and therefore the relative distance from the nucleus
 l represents
 angular momentum quantum number
 angular momentum quantum number indicates
 the relative shape of the orbital
 ml indicates
 the magnetic quantum number
 the magnetic quantum number describes the
 3D orientation of the orbital
 the atoms levels are given by the
 n value
 the atoms levels are divided into sublevels that are given by the
 l value
 l = 0 is what sublevel
 s
 l = 1 is what sublevel
 p
 l = 2 is what sublevel
 d
 l = 3 is what sublevel
 f
 No more than ____ electrons can be in an atomic orbital.
 2
 Pauli Exclusion Principle
 No two electrons can have the same set of quantum numbers.
 Aufbau Principle
 The procedure in which electrons are assigned to orbitals.
 Atomic Size is related to
 the distance between atoms in a sample of the element
 For the main group elements, atomic size generally
 Increases going down a group due to the larger number of outer (valence electrons)Decreases going across a period due to the larger effective nuclear charge
 Ionization Energy
 The energy required to remove an electron from an atom in the gas phase.
 Ionization energies general
 general increase across a period due to the increase in effective nuclear charge decrease down a group due to the increase in size