Ch. 15.1 Kinetic Theory 1.All matter is made of atoms and molecules that act like tiny particles.
Kinetic Theory 2.These tiny particles are always in motion. The higher the temperature, the faster the particles move.
Kinetic Theory 3.The more massive the particles, the slower the particles will diffuse and flow.
Intermolecular forces determine the phase of matter.
Gas Pressure The result of simultaneous collisions of billions of gas particles with an object. The more collisions, the greater the pressure
Vacuum A controlled condition where no gas particles are present. So no gas pressure can exist.
Atmospheric Pressure Results from collisions of air molecules with objects. Decreases as you climb a mountain because the air thins out at higher elevations Measured by a barometer
Measuring Pressure STP (Standard Temp. Pressure) Standard Temperature at sea level is 0 0 C or 273 K Standard Pressure is 101.3 kpa, 760 torr, 760 mm Hg, or 1 atm
Pressure Conversions How many kpa s are in 1.50 atm? 1 atm = 101.3 kpa 1.50 atm x 101.3kPa = 152 kpa 1 atm How many kpa s are in 690 mm Hg? 690 mm Hg x 101.3 kpa = 92 kpa 760 mm Hg
Energy and Temperature Kinetic Energy measures the average speed of particles. The higher the temperature the greater the particle speed. Temperature measures kinetic Energy SI base unit is Kelvin (K)
Converting from Celsius 0 degree Celsius is equal to 273 K K = 0 C + 273 0 C = K 273 Convert 191 K to Celsius 0 C = 191 273 = -82 0 C
Absolute Zero Theoretical temperature at which all motion stops. Scientists have experimented a tenth of degree to 0 K, but have never gotten 0 K.
Ch18.1 Ideal/Real Gases no definite shape. (both) no definite volume. (both) Particles move rapidly in constant random motion (both) State of disorder Low density (both) All collisions perfectly elastic, no attractive forces (Ideal)
Ideal/Real Gases Real gas particles will stick together and attract A real gas will behave like an ideal gas at low pressures or high temperatures Hydrogen and helium always behave ideally due to there small masses.
Gas Relationships Relationships between pressure, volume, temperature and number of moles (amount) While examining relationships, two measurements will always be constant (unchanged)
Pressure vs Volume Real Gas
1. Pressure vs Volume Boyle s Law For a given mass of gas at a constant temperature, the volume of the gas varies inversely with pressure. Pressure increases, volume decreases As volume (space) decreases, the particles become closer and collide (pressure) more often. P 1 V 1 =P 2 V 2
Practice Problem If you had a gas that exerted 202 kpa of pressure and took up a space of 3000.0 ml. If you decide to expand the tank to 7.00 L, what would be the new pressure? (Assume constant temperature) P 1 V 1 =P 2 V 2 Check units 202 kpa x 3.00 liters = P 2 x 7.00 liters 606 = P 2 x 7.00 liters P 2 = 86.6 kpa
Ideal gas
2. Temperature vs Volume Charles Law For a given mass of gas at a constant pressure, the volume of the gas varies directly with its Kelvin temperature. Temperature increases, volume increases As temperature (speed of particles) increases, the particles move farther apart increasing volume (space) while maintaining a constant pressure. V 1 /T 1 =V 2 /T 2 or V 1 T 2 =V 2 T 1
Practice Problem If you took a balloon outside that was at 20.0 0 C at 2.0 liters and heated up to 29.0 0 C, what volume would the balloon occupy now? (Assume constant pressure) V 1 T 2 =V 2 T 1 Check units(remember KELVIN) 2.0 L x 302 K = V 2 x 293 K 604 = V 2 x 293 K V 2 = 2.1 L
CHARLES LAW: ΔT T and ΔV
CHARLES in charge was on TV
Ideal Gas
3. Temperature vs Pressure Gay-Lussac s Law For a given mass of gas at a constant volume, the pressure of a gas varies directly with its Kelvin temperature. Temperature increases, pressure increases As temperature (speed of particles) increases, the particles collide (pressure) more often in a set volume (space). P 1 /T 1 =P 2 /T or 2 P 1 T 2 =P 2 T 1
Ostrich Egg in Microwave
Combined Gas Law Combines all three gas laws into one expression.
Practice Problem You have a 2.0 liter balloon that was at 20.0 0 C and 1.5 atm. If you take this balloon and place it in a room at STP conditions, what volume would the balloon occupy? P 1 V 1 T 2 =P 2 V 2 T 1 (Remember KELVIN) 1.5 atm x 2.0 L x 273 K = 1atm x V 2 x 293 K 819 = V 2 x 293 K V 2 = 2.8 L
4. Moles (amount) vs Temp moles increases, temp. decreases Inverse relationship In a set volume (space), adding more moles of a gas (amount), will cause the particles to slow down (temp.) in order to maintain a constant pressure. Compress tanks become colder as you fill them
Ideal Gas
5. Moles (amount) vs pressure moles increases, pressure increases In a set volume (space), adding more moles of a gas (amount), will cause more collisions (pressure) between gas particles. Think of a super soaker or simply filling your tire
6. Avogodro s s Law (ch19.1) Amount (moles) is directly proportional to the space occupied. The greater the moles of a gas (amount), the more volume (space) the particles will need in order to maintain constant pressure (particles collide) 1 mole of gas at STP= 22.4 liters of any gas
Practice Problem How many liters of Hydrogen are in 6.2 grams of H 2 at STP? Molar of mass of is H 2 2 gram/mole 6.2 grams H 2 x 22.4 L H 2 / 2 gram of H 2 69 L of H 2
Practice Problem #2 What is the volume of hydrogen at STP can be produced when 6.54 grams of Zinc metal reacts with Hydrogen Chloride acid? Zn + 2HCl ZnCl 2 + H 2 6.54 g Zn x 1 mol Zn x 1 mol HCl x 22.4 L H 2 65 g Zn 1 mol Zn 1 mol H 2 = 2.24 L H 2 will form
7. Ideal Gas Law (ch19.1) PV = nrt R = constant 0.08206 (L*atm)/(mol*K) 8.31 (L*kPa)/(mol*K) n = represents the number of moles. Can be used in determining densities of different gases.
Practice Problem A propane tank that holds 3000. g of C 3 H 8. How much larger a container would be needed to hold the same amount of propane if the gas is at 25 0 C and a pressure of 2280 mm Hg?
Solution PV=nRT. First solve for n 3000. g of C 3 H 8. x 1 mole = 44 grams C 3 H 8 68.18 moles 2280 mmhg x 1 atm/760 mm Hg = 3.0 atm V*3.0 atm= 68.18 moles x 0.0821x298K V = 560 L C 3 H 8
Practice Problem 2.0 grams of N 2 is kept under a pressure of 0.95 atm, and a temperature of 30.0 0 C. What is the density of the gas under these conditions?
D =2.0 g / 1.9 L = 1.1g/L N Solution PV=nRT. First solve for n 2.0 g of N 2 x 1 mole = 28 grams N 2 0.071 moles V*0.95 atm= 0.071 moles x 0.0821x303K = 1.9 L D=m/v
8. Graham s s Law of Diffusion (ch18.2) Diffusion is the random scattering of gas molecules. The longer they diffuse the more evenly distributed they will become in the container. The heavier the gas the slower the rate of diffusion.
LAST LAW! I PROMISE (ch18)
Ch. 17.1 Changing States
Changes of State Endothermic Process solid liquid gas Exothermic Process
Melting and Freezing Melting Point is the temperature at which a solid becomes a liquid Melting and freezing take place at the same threshold temperature. According to Kinetic Theory, almost all solids and liquids expand and become disordered when the temperature is raised.
Evaporation Conversion of a liquid to a gas or vapor below its boiling point. It occurs only at the surface. Remember the difference between a vapor and gas. Vapor is normally a liquid or solid at room temperature
Vapor Pressure The pressure exerted by a vapor in equilibrium with its liquid state. Vapor pressure measures how easily a liquid changes into vapor Liquids with high vapor pressures turn into vapors very easily. (Volatile liquids) Ex. Gasoline, perfume
Dynamic Equilibrium Once equilibrium is reached, the vapor particles will begin to condense back to a liquid at the same rate they change into a vapor.
Vapor Equilibrium reached
Boiling Point The temperature at which the vapor pressure of the liquid equals the atmospheric pressure The entire liquid is changing state, not just the surface. Liquids with low boiling points are considered volatile
Difference between Evaporation and Boiling
Super Heated Water
Distillation A method of separating substance with different boiling points. Used in desalinating sea water.
Sublimation Process where solid goes directly to a gas (vapor), because the vapor pressure is so high, liquid phase does not exist. Ex. Iodine, Dry Ice
Condensation The changing of a vapor to a liquid
Liquefaction Changing a gas into a liquid. A gas can be changed into a liquid by two methods: must be placed under tremendous pressure (compressing) Placed in really cold temperature conditions
Intermolecular Forces The forces holding molecules to each other. What phase is strongest? Solids What phase is the weakest? Gases (vapor)
STRONG INTERMOLECULAR FORCES Don t change phase easily High melting points Low vapor pressure Nonvolatile Substances High boiling points High viscosity High surface tension
WEAK INTERMOLECULAR FORCES Do change phase easily Low melting points High vapor pressure Volatile Substances Low boiling points Low viscosity Low surface tension
Heating Curve Used to show how much enthalpy energy (Heat transfer) is needed to change phase. Enthalpy (heat) of Fusion- energy required to change from solid to liquid Enthalpy (heat) of Vaporization- energy required to change from liquid to vapor
Heating Curve
Enthalpy of Vaporization Enthalpy of Fusion
Phase Diagram Shows how states of matter of a substance are affected by changes in temperature and pressure. Triple Point- point where all three states of matter meet. Critical Point- Point where only the vapor can exist.
Ch. 17.2 Liquids Definite volume no definite shape (takes shape of container) Difficult to compress disorderly arrangement on particles Flowing motion of particles
Liquid Properties Viscosity- the resistance of a fluid to flow Thick fluids have high viscosity Ex. Syrup
Liquid Properties Surface Tension- Ability of liquid molecules to hold on to each other. Apparent skin affect Ex. Over filling a liquid in a glass with out the liquid spilling
Hg
Liquid Properties Capillary Rise- the tendency of a liquid to rise in a small diameter tube due to the surface tension of the liquid. Used to measure surface tension of a liquid
Hydrogen Bonding Causes water to be very polar. This bonding also causes water to decrease in density and expand as it freezes (increases space between molecules)
Ch. 16 Solids Definite shape Definite volume Difficult to compress Orderly arrangement of particles Smallest amount of movement of particles.
Metal Solids Solid Structures Crystal structure (repeating patterns) Allotropes (different forms of same element, ex. Carbon) Amorphous (no crystal structure) Glasses, rubber, plastics