Thermodynamics

Question 1

What is the equation for the change in internal energy?

Answer 1

ΔE = q + w

Change in internal energy = heat + work

Question 2

What is the PV work equation?

Answer 2

w = -PₑₓₜΔV

Work = external pressure * change in volume

Question 3

What is the equation for Enthalpy?

Answer 3

ΔH = qₚ

Enthalpy = heat at constant pressure

Question 4

What does ΔH > 0 mean?

Answer 4

The reaction is Endothermic, sucking up heat.

Question 5

What does ΔH < 0 mean?

Answer 5

The reaction is Exothermic, giving off heat.

Question 6

What is the ΔH when 2H₂(g) + O₂(g) → 2H₂O(ℓ)

Answer 6

ΔHᵣₓₙ = -572KJ

Question 7

What is the phase change from Solids to Liquids called? Endothermic or Exothermic?

Answer 7

Melting/Fusion

ΔH > 0, Endothermic

Question 8

What is the phase change from Liquids to Gases called? Endothermic or Exothermic?

Answer 8

Boiling/Vaporization

ΔH > 0, Endothermic

Question 9

What is the phase change from Solids to Gases called? Endothermic or Exothermic?

Answer 9

Sublimation

ΔH > 0, Endothermic

Question 10

What is the phase change from Gases to Liquids called? Endothermic or Exothermic?

Answer 10

Condensation

ΔH < 0, Exothermic

Question 11

What is the phase change from Liquids to Solids called? Endothermic or Exothermic?

Answer 11

Freezing/Crystallization

ΔH < 0, Exothermic

Question 12

What is the phase change from Gases to Solids called? Endothermic or Exothermic?

Answer 12

Deposition/Vapor Deposition

ΔH < 0, Exothermic