AP Chemistry Thermodyanmics Flashcards

9505307904	1st Law of Thermodynamics	energy of universe is constant	0
9505307905	2nd Law of Thermodynamics	process spontaneous in one direction can't be spontaneous in reverse direction	1
9505307906	state function	∆H, ∆S, ∆G	2
9505307907	energy released	bonds formed; exothermic	3
9505307908	energy absorbed	bonds broken; endothermic	4
9505307909	∆H	H(products)-H(reactants)	5
9505307910	heat of formation	∆H = ∑H(products)-∑H(reactants)	6
9505307911	heat capacity	heat ÷ ∆T	7
9505307912	specific heat	q = mc∆T	8
9505307913	Gibbs free energy	measure of spontaneity of process	9
9505307914	∆G negative	spontaneous	10
9505307915	∆G positive	not spontaneous	11
9505307916	∆G = 0	reaction at equilibrium	12
9505307917	∆G°	∆H - T∆S	13
9505307918	∆G	∆G° + RT(lnQ)	14
9505307919	R (in thermo, not gases)	8.31 J/mol*K	15
9505307920	exothermic reaction	reactants start higher than products	16
9505307921	endothermic reaction	reactants start lower than products	17
9505307922	entropy	measure of disorder of system	18
9505307923	particles	in solution have higher entropy values than solids	19
9505307924	2 moles of substance	have higher entropy value than one mole	20
9505307925	entropy change ∆S	∑S°(products) - ∑S°(reactants)	21
9505307926	standard state conditions	1. all gases are at 1 atm 2. all liquids are pure 3. all solids are pure 4. all solutions are at 1-M 5. the energy of formation of an element in its normal state is defined as 0 6. temperature used for standard state values is almost invariably room temperature. standard state values can be calculated for other temperatures, however.	22
9505307927	heat of vaporization	energy given off when substance condenses	23
9505307928	heat of fusion	energy taken in by substance when melts	24
9505307929	addition of catalyst	decreases activation energy only	25
9505307930	spontaneous endothermic reaction	∆H > 0 ∆S > 0	26
9505307931	spontaneous process	one that proceeds on its own without assistance, they are irreversible unless the surroundings are changed and they can be fast or slow	27
9505307932	Exothermic Reactions	negative ∆H, favors spontaneity but does not guarantee it.	28
9505307933	Entropy of a system increases when	gases are formed from solids or liquids, liquids or solutions are formed from solids, the number of gas molecules changes during a chemical reaction	29
9505307934	standard entropy	S° is the absolute entropy of a mole of a substance at 1 atm and 35°C. J/Mol K. for all elements and compounds the standard entropy is always positive.	30
9505307935	+∆S	becomes more random; disordered	31
9505307936	-∆S	becomes more ordered	32
9505307937	standard molar entropies of elements and diatomics	are not 0 unlike standard molar enthalpies	33
9505307938	standard free energy	∆G°(rxn) is the free energy change of a reaction when it occurs under standard conditions; when reactants in their standard states are converted to products in their standard states.	34
9505307939	∆G°rx	= ∑n∆G(f°products) - ∑n∆G°reactants	35
9505307940	spontaneous at all temperatures	-∆H (favorable) +∆H (favorable)	36
9505307941	nonspontaneous at all temperatures	+∆H (unfavorable) -∆S (unfavorable)	37
9505307942	spontaneous at low T; nonspontaneous at high T	-∆H (favorable) -∆S (unfavorable)	38
9505307943	spontaneous at high T; non spontaneous at low T	+∆H (unfavorable) +∆S (favorable)	39
9505307944	-∆G	the forward process is spontaneous (the reverse is nonspontaneous)	40
9505307945	+∆G	the forward process is nonspontaneous (the reverse is spontaneous)	41
9505307946	Phase transitions	if the process is melting, the ∆H is the same as the heat of fusion. if the process is freezing, the ∆H is the negative value of the heat of fusion. if the process is boiling, the ∆H is the heat of vaporization. if the process is condensing, the ∆H is the negative value of the heat of vaporization.	42
9505307947	what does Q stand for	reaction quotient: the mass action expression at non-equilibrium conditions. the spontaneity of a reaction that has not reached equilibrium has to be measured in terms of ∆G which is not synonomous with ∆G° because the substances are not in standard state	43
9505307948	Finding ∆G when ∆G° and Q are known	∆G = ∆G° + RTlnQ	44
9505307949	Enthalpy (heat) of combustion	the heat released or absorbed (enthalpy change) during the formation of a pure substance from its elements, at constant pressure and usually denoted by ΔHf.	45
9505307950	Hess's law	The overall enthalpy change in a reaction is equal to the sum of the enthalpy changes of the individual steps of the process.	46
9505307951	Calorimeter insulated device used for measuring the amount of heat absorbed or released through a chemical or physical process	insulated device used for measuring the amount of heat absorbed or released through a chemical or physical process	47
9505307952	bomb calorimeter sealed, insulated container used for measuring the energy released during combustion	sealed, insulated container used for measuring the energy released during combustion	48
9505307953	heating curve	a diagram that shows the temperature changes and changes of state of a substance as it is heated	49
9505307954	potential energy diagram	a diagram that shows the changes in potential energy that takes place during a chemical reaction	50