CHEM 1211 Chap 6, 7, 8.4 – Flashcards
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| first law of thermodynamics |
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| _____________ states that when energy is exchanged or transformed the energy is still there. The total amount of energy in the universe before the change has to equal the total after. |
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| internal energy E |
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| The _________ is the total amount of kinetic and potential energy a system possesses. |
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a. The change in the system's internal energy b. heat (thermal energy) c. work energy (transfer of energy) |
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?E = q + w ? E represents a._______ q represents b.______ w represents c.______ |
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| Work |
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| Energy |
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Law of conservation of energy created nor destroyed |
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| ______________- energy can be converted from one form to another, but can never be ______ nor ______, only transferred |
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| Thermodynamics |
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| The study of energy is called _________. It studies the exchange of energy between the system and the surroundings. |
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| joule (J) |
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| One _____ is the amount of energy needed to move a 1-kg mass a distance of 1 meter. |
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| calorie (cal) |
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| One ______ is the amount of energy needed to raise one gram of water by 1 degrees C |
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| system, surroundings |
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| Transfer of Energy is defined in terms of _______ and ________ |
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| system |
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| The ______ is defined as the material or process that contains the energy changes we are studying. |
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| surroundings |
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| The __________ are defined as everything else in the universe. |
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| beginning and end |
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| The ?E of a system depends only on the amount of energy in the system at the ____________, not the transfer. |
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+ Endothermic |
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If energy is added ?E = Heat flow is into a system, Absorb energy from the surroundings |
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- Exothermic |
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If energy is removed ?E = Heat flows out of the system, Releases energy to the surroundings |
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| positive |
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Endothermic Process: Heat (q) is |
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| negative |
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Exothermic Process: Heat (q) is |
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| heat exchange (q) or work (w) |
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| ________ is exchanged between the system and surroundings through either _________ or _______ being done. |
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| heat |
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| ______ involves the transfer of energy between two objects due to a temp. diff. |
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| negative |
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| System does work on surroundings w is |
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| positive |
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| Surroundings do work on the system w is |
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| q (heat) and w (work) |
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| Energy is a state function, but ___ and ___ are NOT state functions, their values depends on the process |
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| specific heat Cs units J/(g.C) |
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| The ________ capacity is the amount of heat energy required to raise the temp of one gram of a substance 1 degree C |
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| molar heat |
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| The ________ capacity is the amount of heat energy required to raise the temp of one mole of a substance 1 degree C |
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| Specific Heat Capacity |
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| The measure of a substance's intrinsic ability to absorb heat. |
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| q = (m) x (Cs) x (ΔT) |
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| We can calculate the quantity of heat absorbed by an object with the formula |
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| postive, negative |
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| When gases expand, ΔV is _____, but the system is doing work on the surroundings (exerting a pressure), so wgas is ____. |
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external pressure • change in vol. w = -PΔV |
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As long as the external pressure is kept constant, work of a "gas" can be calculated using this formula. -work = |
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| 101.3J = 1 atm • L |
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| To convert the normal units for work (joules) to fit the formula w = -PΔV, use ______ |
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qsystem or q = ΔE + 0 b/c work = 0 if there is no change in vol. |
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At constant volume, ΔEsystem = (usually measured in kJ/mol of substance) |
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| enthalpy, H |
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| The _______ of a system is the sum of the internal energy of the system and the product of pressure and volume. Is a state function |
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| ΔH = ΔE + ΔPV P is constant |
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| The formula to measure the energy of a reaction, in terms of heat, when volume can not be constant. |
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| enthalpy change, ΔH |
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| The _________ of a reaction is the heat evolved in a reaction at constant pressure. |
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| ΔHreaction = qreaction at constant pressure |
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| The formula for the change in enthalpy of a reaction at constant pressure is |
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ΔE + PΔV = q
q |
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at constant pressure ΔH = _________ at constant volume ΔE = _ |
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| heat |
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| Energy needed for a chemical reaction is absorbed or released as ______. |
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| heat of reaction (ΔH) |
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| The _______ is the amount of heat absorbed or released during a rxn, and is the diff. in the energy of the products and the reactants. |
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| ΔH = ΔHproducts - ΔHreactants |
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| The formula to calculate the heat of reaction (ΔH) is |
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| endothermic |
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| In an __________ reaction, the energy of the products is greater than the energy of the reactants, heat is absorbed (+) |
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| exothermic |
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| In an ________ reaction, the energy of the products is less than the energy of the reactants, heat is released (-) |
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| the same whether the rxn happens in one or multiple steps. |
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| Hess's Law states in going from a particular set of reactants to a particular set of products,;;H is... |
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| the sum of the heats of reaction for each step. |
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| Hess's Law also states that if a reaction can be expressed as a series of steps, then the ΔHrxn for the overal reaction is... |
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ΔHrxn = [cΔHf (C) + dΔHf (D)] - [aΔHf (A) + bΔHf (B)] |
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a A + b B → c C + d D ΔHrxn = ∑ n ΔHf (products) - ∑ n ΔHf (reactants) Write out what the equation would be using letters. |
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standard states
zero |
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| Elements in their _________ are not included in the ΔHrxn calculations b/c ΔHf for an element like this is _____. |
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| Electromagnetic radiation |
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| Describes energy of light in terms of wavelength and frequency. Moves at speed of light in a vacuum. Energy that travels as waves through space. |
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| wavelength (λ) |
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distance between two peaks or troughs in a wave. units is m or nm,etc |
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| frequency (v) |
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number of waves (cycles) per sec. that pass a given point in space. units are hertz (Hz) or cycles/s = sec-1 1 Hz = 1 sec-1 |
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| 3.00 x 108 m/s |
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| Speed (c) of light = |
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| c = λ v |
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| To calculate the way energy travels through space is. |
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| wavelength or frequency |
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| The color of light is determined by its ________ or _________. |
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| lowest to highest (RIVUX G) |
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| The electromagnetic spectrum arranges all forms of light energy from _____ to _____. |
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| longest to shortest |
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| The electromagnetic spectrum arranges energy from _______ to ______ wavelengths. |
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| varying energies |
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| Different atoms have varying amounts of electrons with... |
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| quantized |
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| When an atom is heated up and the energy passed through a prism, the "spectrum" of colors is NOT continuous. Instead energy of an electron is __________. Meaning each "color" corresponds to the energy of each electron in the atom. |
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| photons |
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| Electromagnetic radiation in atoms is a stream of "particles/e-" called... |
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Ephoton = hv = hc λ |
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| How we relate energy of an atoms electrons to the electrons frequency, speed, wavelength is by using the formula... |
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The model only works for hydrogen. Electrons do not actually move around the nucleus in circular orbits/pathways |
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| Bohr's model does correctly fit the idea of quantized energy levels. However this model is not totally correct b/c? |
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| Heisenberg uncertainty principle |
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| Which principle states that... there is a fundamental limitation to just how precisely we can know both the position and momentum of an electron at a given time. |
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| randomly...so...we can not predict at any one moment where exactly the electron will be. |
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| An electron is always moving _______ so... |
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| orbital |
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| There is a "probability" of where an electron may be at a particular moment. This "probable" space we call an ________. A 3-D e- density map. |
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| quantum numbers |
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| The size, shape, and orientation in space of an electrons orbital is determined by 3 integer terms called... |
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| principal |
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| ______ quantum number (n) - describes size and energy level or orbitals (distance of e- from nucleus). Has integral values of 1,2,3... The larger the value of n, the more energy the orbital has. |
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| angular momentum |
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| ________ quantum number (l) - shape of atomic orbitals (sometimes called a subshell). Shape of orbital usually referred to w/ a letter (s,p,d, or f) and has integral values of 0 to n-1 |
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| magnetic |
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| _________ quantum number (ml);- orientation of the orbital in space relative to the other orbitals in the atom. Has integral values of -l to l (including 0) |
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| Electron spin |
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| ___________ quantum number (ms) - can be +1/2 or -1/2. Refers to "spin" orientation of electrons. |
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| increase |
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| Energy of electrons _______ as they get further from nucleus. |
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| s |
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| __ orbital has a spherical shape around the nucleus. Each principal energy state (n) has this orbital. Lowest energy orbital in a principal energy state. |
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| Pauli exclusion |
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| _________ ;principle - states that in a given atom no two electrons can have the same set of four quantum numbers. (due to repulsions) |
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| two |
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| Each orbital (ml) can hold only ____ electrons, and they must have opposite spins. (to decrease repulsion) |
