Question | Answer |
Phases in Detail: Gases | - molecules spread out and fill spaces they are given
- weak intermolecular forces of attraction
- large spaces between particles |
Evaporation | takes place at all temperature on the liquid/ vapor boundary
-increases with an increase in temperature |
Vapor | definition: a gaseous phase of a substance that is a liquid or sold at normal conditions
- once liquid particles have absorbed enough energy to overcome attractive forces, they become this |
Vapor Pressure | gas particles exert pressure on the liquid when they evaporate
- In closed system, pressure increases (ex: lid on top of boiling water; nothing in/out)
-increases with an increase in temperature |
Reference Table H #1 | -101.3 kPa= standard pressure (Table A)
-1 atm, 760 turr, 760mmHg are values equivalent to Standard Pressure |
Reference Table H #2 | -Normal boiling point: when the vapor pressure is equal to atmospheric pressure
-When a substance boils, evaporation occurs throughout the liquid
-Measures the strength of intermolecular forces between molecules
-When a substance |
Intermolecular forces between molecules | 1) If the vapor pressure is high- the attraction between molecules are weak (propanone)
2) If the vapor pressure is low- the attraction between molecules are strong (ethanoic acid) |
4 main types of energy | 1) Kinetic Energy (KE): Energy in Motion
2) Potential Energy (PE): Stored Energy
3) Chemical Energy (Energy assorted with a chemical change
4) Heat Energy |
Heat Energy | Amount of energy transferred from one substance to another
- can be measures using a calorimeter
- calories (cal) or joules (J) measure heat gain or loss
- to convert from cal to J to Kcal or KJ: divide by 1,000 |
Law of Conservation of Energy | - energy is neither creates or destroyed
1. energy can be transferred from one substance to another
2. Or energy can be transferred into a new form of energy
3. the TOTAL AMOUNT OF ENERGY WILL REMAIN THE SAME |
(Thermometry): Temperature | the measure of the average kinetic energy of the particles of a substance |
(Thermometry): Heat | 1. flows spontaneously from a hot object to cold object
ex: body heat to chair, boiling water to hand, burned hand to icepack |
(Temperature Scales): Degrees Celcius (°C) | -most commonly used scale
- temps below zero are negative
-2 fixed points
- 0°C: melting/ freezing point of water
- 100°C: boiling/ condensation of water
- values on a thermometer increase by 1°C |
(Temperature Scales): Kelvin #1 | -contains theoretically the lowest possible temperature/ 0 Kelvin (absolute zero)
- has never been exactly reached (1/1000 K)
- Absence of all kinetic energy (no motion of particles)
- scale is the same as Celcius, just shifted by 273 |
(Temperature Scales): Kelvin #2 | -1 degree change in Celcius is the same as 1 degree change in Kelvin
-Table T: K= °C + 273 |
Thermometers | - device used to measure the average kinetic energy of particles and temp
- uses liquids like Hg (Mercury) and colored alcohols that expand at high temperature |
Measurement of Heat Energy | the amount of heat given off or absorbed in a reaction |
(Table T): q=mc▲T
#1 | q= heat (in Joules or calories)
m= mass of substance (g)
c= specific heat capacity of substance (J/g°C)
▲T= final temp-initial temp (in °C) |
(Table T): q=mc▲T
#2 | *ONLY USED when there is a CHANGE IN TEMP
1. the amount of heat needed to raise 1.0g of a substance by 1.0°C
2. the value for specific heat of water is on Table B |
(Table T): Heat of Fusion | the amount of heat needed to MELT 1.0g of a substance
*q=mHf is used when calculating how much heat is absorbed when a substance MELTS or FREEZES (Table B)
**(NO CHANGE IN TEMPERATURE)** |
(Table T): Heat of Vaporization | the amount of heat needed to VAPORIZE(boil) 1.0g of a substance
*q=mHv is used to calculate how much energy absorbed when a substance BOILS or how much energy is released when a substance CONDENSES
**(NO CHANGE IN TEMPERATURE)** |