Enthalpy
What is entropy a measure of?
Disorder
What main equation is used to find change in Gibbs Free Energy of a reaction/system?
ΔG = ΔH - T ΔS
Which one of the following thermodynamic quantities is not a state function?
(a) Gibbs free energy
(b) entropy
(c) internal energy
(d) work
(d) work
2nd law of thermodynamics: To have a spontaneous process ΔSuniv ____ 0 and ΔGsys ____ 0
ΔSuniv > 0
ΔGsys < 0
If a reaction is endothermic: ΔH has a __ sign and ΔS has a __ sign
ΔH: positive
ΔS: negative
Which reaction will be more likely to occur: one in with the entropy is positive or one in which the entropy is negative?
The one in which the entropy is positive
The entropy and enthalpy of a high temperature reaction are both negative. Is the reaction spontaneous?
The reaction is nonspontaneous
What does calorimetry measure?
The heat flow of a system(s) during a reaction
Rank entropy from highest to lowest in relation to the states of matter.
Solid<Liquid<Gas
If a system decreased in enthalpy would it be exothermic or endothermic?
Exothermic, as the change in enthalpy value will be negative
Solid nitrogen spontaneously sublimes into nitrogen vapor. Explain how this would be represented in a change in entropy (states of matter).
Entropy will increase because gases have greater entropy than solids
True or false: Gibbs Free Energy is the true predictor of spontaneity?
True
What is the equation for 𝚫Ssurr when temperature and pressure are constant?
𝚫Ssurr = -𝚫Hsys / T
True or False: endothermic processes are always nonspontaneous
False - enthalpy isn't a perfect predictor
N2(g)+O2(g)→2NO(l)
In the above reaction, heat is given off and NO has an entropy value of 32 kJ, N2 an entropy value of 65 kJ, and O2 an entropy value of 80kJ. What is the change in entropy of formation of this reaction?
-81 kJ
A reaction reacts at a low temperature of 45℃ and has a ΔH of -81.22 kJ and a ΔS of -175.75 J/K. What is the ΔG for this reaction?
-25.3 kJ
The temperature at which a reaction changes from spontaneous to nonspontaneous can be calculated with what equation?
T = ΔH/ ΔS
The chemical equation for methanol is: CH3OH(l) + 3/2 O2(g) ---> CO2(g) + 2 H2O(g). Based on the reaction predict the sign of ΔS
ΔS will be positive
At 215K, a reaction gives off an enthalpy value of -40 kJ and the corresponding change in Gibbs Free Energy is 20 kJ. What will the change in entropy be in this reaction?
-0.28 kJ
For a generic process A → B, ΔH° = 151 kJ/mol and ΔS°= 121 J/K-mol. Assuming that ΔH° and ΔS° do not change with temperature, at what temperature in °C does the reaction go from being non-spontaneous to spontaneous?
The process is spontaneous when T > 1247.9K
Calculate ΔS° of the surroundings for the synthesis of N2O + NO2 ⟶ 3 NO. (T = 298K and P = 1atm). The standard enthalpies for the compounds are N2O = 87 kJ, NO2 = 54 kJ, and NO = 92 kJ
-453 J/K
What does it mean for a function to be a state function?
The path taken does not matter, just the final - initial values