Phases Flashcards
Relate phase changes and whether the change is an endo or exothermic reaction.
Gases require the highest amount of energy while solids require the lowest amount of energy. If a molecule goes towards gases then it is an endothermic reaction. If a mole goes towards the solid state then it is an exothermic reaction.
What does delta H represent?
The change in enthalpy, whether the reaction is at a higher or lower energy level– endothermic or exothermic.
What is isothermal?
Same temperature.
What is isobaric?
Same pressure.
What is isochronic?
Same volume.
What is adiabatic?
No heat exchange.
What is the triple point?
The point where all three phases are in equilibrium.
What is the critical point?
The highest temperature and pressure where liquids can occur.
What is the supercritical point?
Gases and liquids are indistinguishable.
How can you identify water’s phase diagram?
negative slope along the solid and liquid line.
Water trivia:
- Liquid form is more dense than the solid form.
2. Extremely high boiling point for its size.
What do the plateaus mean on heating curves?
The molecules are changing states. The plateaus occur at a CONSTANT temperature.
What is heat capacity?
The amount of heat required to change one gram of a substance by one degree Celsius .
The flatter the slope(line), the greater the heat capacity
Compare delta H of phases
Delta H Sublimation > Delta H Vaporization > Delta H Fusion.
What is vapor pressure?
the pressure above the liquid when the forces of condensation and evaporation are at equilibrium.
Relate vaporization rate with vapor pressure.
As the rate of vaporization increase, the vapor pressure decreases.
Relate vapor pressure and boiling point.
As the boiling point of a liquid increases, then the vapor pressure decreases.
Relate vapor pressure and temperature
As the temperature increases, then the vapor pressure increases EXPONENTIALLY.
Relate hov, volatility, boiling point, and vapor pressure.
As the heat of vaporization increases, volatility decreases, boiling point increases, vapor pressure decreases.
What are the two ways of defining boiling point? What are the consequences?
- Boiling point is substance is no longer a liquid.
- Boiling point is when the vapor pressure equals atm pressure.
This means, the lower the atm the lower the boiling point. Which is the case at higher elevation.
What are three ways to effect boiling point?
- Increase solute concentration to increase BP.
- Increase elevation so the atm pressure is lower to DECREASE BP.
- Decrease elevation so there is more atm pressure to increase Bp.
What is Raoult’s Law?
The Vapor pressure = (X/ total moles) Pure vapor pressure.
What do solutes do the melting and boiling point of a solution?
Decrease melting point and increase boiling point.
What is the formula for freezing point depression and boiling point elevation
Tx= Kim
What is the formula for osmotic pressure?
osmotic pressure = iRMT.
