Phase Change Diagrams
What is the phase change that occurs when a liquid becomes a solid?
Freezing
Is the potential energy diagram endothermic or exothermic?
Exothermic
What type of reaction absorbs heat from surroundings? Must write the whole word.
Endothermic
How much heat is absorbed by 50g water when it changes from 20°C → 30°C?
2,090 J
Based on the following equation, how much heat is released when 2.00 moles of CH4 are burned?
CH4 + 2O2 → CO2 + 2H2O ∆H= -890 kJ
-1780 kJ
Name two phase changes that are exothermic?
TWO:
Condensation, Freezing, Deposition
What do we call the difference in potential energy between reactants and products?
ΔH
Change in Enthalpy
Q
Heat of the Reaction
What base unit is used to measure energy?
Joule (J)
If 100g of a liquid absorbs 2000 J and rises 10°C, what is the liquid's specific heat?
2 J/g°C
Based on the reaction, how much heat is released when 36.0 g of water is formed?
2H2 + O2 → 2H2O ∆H= -572 kJ
−572 kJ
What is happening to kinetic energy during phases A, C, & E?
Increasing
What is the peak of the curve on the potential energy diagram called?
Activated Complex
What characteristic causes a metal spoon feel hotter than a wooden spoon?
Specific Heat
How much energy is needed to melt 150. g of ice?
50,100 J
Based on the reaction, how much heat is released when 34.0 g of NH₃ is produced?
N2 + 3H2 → 2NH3 ΔH= −92.0 kJ
−91.8 kJ
Which line segment represents BOTH liquid and gas?
D
From the potential energy diagram, calculate the activation energy for the forward reaction.
60 kJ
How do you find ΔT?
Final Temp - Initial Temp
How many Joules are given off when 145 g of steam condenses to liquid water?
−328,000 J
Based on the reaction, how much heat is released when 44.0 g of CO₂ is formed?
2CO + O2 → 2CO2 ΔH= −566 kJ
−283 kJ
What is the boiling point according to the heating curve diagram?
150°C
Using the potential energy diagram, what is ΔH of the reverse reaction? Must include either a positive sign or a negative sign.
+20 kJ
What do you call the phase change that goes directly from solid to gas?
Sublimation
A 50.0 g piece of metal absorbs 2100 J of heat and its temperature increases from 20.0°C to 30.0°C. What is the specific heat of the metal?
4.2 J/g°C
Based on the equation, how much heat is released when 60.0 g of CO₂ is produced?
2C2H6 + 7O2 → 4CO2 + 6H2O ΔH= −3120 kJ
−1060 kJ