Gen chem 5 Heat capacity, phase change, colligative properties.txt

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• Def phase
• If all intensive macroscopic properties are constant, the system is homogenous and can be considered a phase
1. What does it mean when a phase change occurs, and what are the two mechanisms capable of creating a phase change
• When a phase changes, it means the internal energy has changed, or the space between molecules has changed.
• Work and heat can change a phase
2. Def heat capacity and give equation. what is a better name for it hint: more accurate description
A measure of the energy needed to change the temperature of a substance. Or the amount of energy a substance can absorb before changing temperature. Puts an energy quantity to each thermal unit.

• C=q/(dT)
• Internal energy capacity
3. How many types of heat capacities are there for any one substance. What are they
• 2
• Constant volume heat capacity
• Constant pressure heat capacity
4. Which is greater, Cv or Cp
Cv > Cp
5. What are the heat capacity equations and when do you use each? What are the symbols for each
• q=C(dT): heat capacity of an over all system
• q=mc(dT): specific heat capacity - heat capacity per unit mass
• Specific heat symbol: c
• Heat capacity symbol: C
6. What is the specific heat capacity if water
c(water)=(1 cal)/(g*Celcius)
7. What is a calorimeter, what are the two types, and info do we get from each
• Calorimeter: device used to measure energy change
• Constant pressure: coffee cup calorimeter (because done at atmospheric pressure) tells heats of reaction
• Constant volume: bomb calorimeter tells internal energy change
8. Define heat of fusion and hear of vaporaization
• Heat of fusion: solid to liquid phase change (melting/freezing)
• Heat of vaporization: liquid to gas phase change (vaporization/condensation)
9. Define triple point, critical temperature, critical pressure, critical point
• Triple point: Single point where a substance can exist in equilibrium in all three phases simultaneously
• Critical temperature: temp above which a substance cannot be liquified, regardless of the pressure added
• Critical pressure: the pressure required to produce liquidification of a substance at critical temp
• Critical point: point defined by a substances critical temp and pressure. Beyond this point, a liquid has gas a liquid characteristics
10. What is a colligative property. What are these properties
• Colligative property: a property which depends on n umber of particles involved only. Type does not change anything
• 1. Vapor pressure
• 2. Boiling point
• 3. Freezing point
• 4. Osmotic pressure
11. Give equation for boilling point elevation. Why is this phenomena observed
• dT=k(b)mi
• k(b)= specific constant of substance being boiled
• m= molality
• i= van't Hoff factor = number of particles a single solute will dissociate into when put in solution
• Nonvolatile solutes lower vapor pressure which in turn raises boiling point
12. What is freezing point depression and how is it similar/different from boiling point elevation (bpe). What is the equation
• Freezing point depression: change in melting point due to addition of solute
• Same as bpe because a nonvolatile solute must be added to an ideally dilute solution for an effect
• Different because it is not vapor pressure which is changed, but impurities in crystallization are created which lower freezing point
• Same as bpe, but use k(f) instead of k(b)
13. Define osmotic pressure. What is the equation.
• Measure of waters desire to move into a substance due to osmosis
• Pi=iMRT
 Author: p.reilly1227 ID: 233864 Card Set: Gen chem 5 Heat capacity, phase change, colligative properties.txt Updated: 2013-09-09 22:26:52 Tags: Gen chem Heat capacity phase change colligative properties Folders: Description: Gen chem 5 Heat capacity, phase change, colligative properties.txt Show Answers: