Thermochemistry
Bond Enthalpy Calculations
Heating Curves
Heating Curves Calculations
Vocabulary
Phase Change Diagrams
100
Is the formation of chemical Bonds Endothermic or Exothermic?
Exothermic
100
Draw the structure for pentane
100
What phase (or phases) are present during segment A?
Solid
100
How much heat is required to raise the temperature of 100 g of water from 20°C to 50°C?
12,540 J
100
Why is more energy required for vaporization than for fusion?
When particles go from a liquid → gas, they must separate completely and move far apart, which requires breaking most or all intermolecular forces.
100
What is the transition phase from solid to gas?
Sublimation
200
Is water evaporating endothermic or exothermic?
Endothermic: energy is being absorbed by the water
200
Draw this organic compound: C4H8
200
What phase change, if any, is occurring during segment DE?
Liquid to gas
200
How much heat is required to melt 50 g of ice at 0°C?
ΔHfus= 334 J/g
16,700 J
200
The lowest temperature that is theoretically possible, at which motion of particles that constitutes heat would be minimal
Absolute Zero, 0 Kelvin, or -2730C
200
What is the transition phase from gas to solid?
Deposition
300
I thi Reaction Endothermic or Exothermic?
Exothermic
300
Calculate the bond enthalpy for the reaction.
Is the reaction endothermic or exothermic?
678 - 862 = ~ -184 kJ/mol
Exothermic
300
What phase (or phases) are present during segment BC?
Solid and Liquid
300
How much heat is required to convert 60.0 g of water at 25.0°C into steam at 110.0°C?
ΔHfus= 334 J/g
ΔHvap= 2260 J/g
155,616 J
300
The specific temperature and pressure at which a substance exists in all three phases at the same time: solid, liquid, and gas.
Triple Point
300
At 30 atmospheres pressure, the boiling point of this substance is:
50 ºC
400
Calculate the energy, in Joules, that would be released if you ate 104 g of this food
502,000 J
400
Calculate the bond enthalpy of this reaction
6494 - 8528 = ~-2034 kJ/mol
400
At what segments does the latent heat of fusion occur?
CB
400
How much total heat is required to convert 75.0 g of ice at −15.0°C into steam at 120.0°C?
ΔHfus= 334 J/g
ΔHvap= 2260 J/g
231,000 J
400
The specific temperature and pressure at which the distinction between a liquid and a gas disappear
Critical Point
400
A phase change from Phase B to Phase C is known as:
Freezing
500
Draw the potential energy diagram (graph) for an exothermic reaction, label Enthalpy (ΔH) and Activation energy (Ea)
500
Calculate the enthalpy of combustion of ethane using bond enthalpies
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
9117 - 11948 = ~ -2800 kJ/mol
500
At what segments does the latent heat of vaporization occur?
DE
500
How much total heat is required to convert 125 g of ice at −25.0°C into steam at 130.0°C?
ΔHfus= 334 J/g
ΔHvap= 2260 J/g
390,569 J
500
How old is Cricket?
2
500
The triple point of this substance occurs at:
- 15 ºC and 6 atmospheres