Hotness
How Problematic
Disorder
Miscellaneous
100
What is the thermal energy content of a system at a constant pressure?
Enthalpy
100
Billy Robert has a 18.03 g sample of copper at 39 oC. If the temperature changes to 90.0 oC, how much energy has been added? csp = .38
349 J
100
What happens to the total entropy of the universe over time?
Increases
100
What is an insulated container in which the temperature change of a chemical reaction can be detected?
Calorimeter
200
What type of reaction is most favorable because it involves less energy needed to go from weaker bonds to stronger bonds?
Exothermic
200
Daily Double!
Calculate the enthalpy and entropy changes for the following reaction, and state whether it is exothermic or endothermic.
Ca (s) + 2H2O (l)→ Ca(OH)2 (aq) + H2 (g)
ΔHof = -413.6 kJ
ΔSo = 32.5 J/K
exothermic reaction
200
What is the enthalpy change to produce 1 mol of a compound in its standard state from its elements in their standard state?
Standard molar enthalpy of formation
200
What is the amount of thermal energy required to raise the temperature of 1 g of the substance by 1 oC?
Specific heat
300
Draw a graph of an endothermic reaction.
300
Kanye West has a 329.2 g sample of pure ice at -2 oC. If 150000.0 J of energy is added, what is the final temperature and state of his sample?
27.21 oC
Liquid
300
What is molar enthalpy of fusion?
The thermal energy required to turn a mole of solid to a liquid
300
What is standard molar enthalpy of combustion?
The thermal energy released by the complete burning of one mole of a substance at standard conditions
400
What unit is entropy measured in?
J/(mol*K)
400
For the following equation, calculate Gibbs free energy change, state whether or not it's favorable, and state whether or not its exothermic.
N2 (g) + 3H2 (g) → 2NH3 (g) at 100.0 K
ΔGo = -71.99 kJ
Favorable
Exothermic
400
Calculate ΔHof and ΔSo for the following reaction and state whether or not it is exothermic.
2Al (s) + Fe2O3 (s) → 2Fe (s) + Al2O3 (s)
ΔHof = -851.5 kJ
ΔSo = -38.5 J/K
exothermic
400
What is entropy?
The dispersal of usable energy
500
What is the difference between latent heat and sensible heat?
Latent heat - the thermal energy that produces a phase change when transferred to a substance
Sensible heat - the transfer of thermal energy that produces a temperature change in a substance
500
For the following equation, calculate Gibbs free energy change, state whether or not it's favorable, and state whether or not its exothermic. For CS2, enthalpy of formation is 89.4 kJ/mol and entropy is 151.3 J/(mol*K).
C (s) + 2S (s) → CS2 (l) at 295 K
ΔGo = 64.8 kJ
Not favorable
Endothermic
500
State the favorableness of each case involving Gibbs free energy:
Enthalpy increases, entropy decreases
Enthalpy increases, enthalpy increases
Enthalpy decreases, entropy decreases
Enthalpy decreases, entropy increases
Enthalpy increases, entropy decreases = unfavorable
Enthalpy increases, enthalpy increases = favorable at high temps
Enthalpy decreases, entropy decreases = favorable at low temps
Enthalpy decreases, entropy increases = favorable
500
What type of reactions have a positive ΔHr value?
Endothermic