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Chemistry Topic 4
Physical Behavior of Matter
• 11/30 Chemistry
• Unit 4 – Physical Behavior of Matter
• Aim: What are the 3 states of matter?
• Obj: SWBAT compare and contrast the states of matter
• Do now:
2H2 + O2 2H2O
How many moles of O2 are needed to produce 40 moles of H2O?
• 3 States of matter
– Solid (s)
– Liquid (l)
– Gas (g)
Solids
• Definite volume
• Definite shape
• Crystalline structure
Liquids
• Definite Volume
• No Definite Shape – takes the shape of its container
Gases
• No Definite Volume – COMPLETELY fills the volume of its container
• No Definite Shape – takes the shape of its container
Temperature
• Measurement of the average kinetic energy of particles
Heating Curve
Cooling Curve
• 12/1 Chemistry
• Unit 4 – Physical Behavior of Matter
• Aim: How is heat transferred?
• Obj: SWBAT calculate heat transfers
• Do now: Worksheet
• Homework: Worksheet
Phase Changes
• Sublimation – changing from solid to gas directly (without being liquid)
– Ex. CO2, I2, and naphthalene (moth balls)
• Deposition – changing from gas to solid directly (without being liquid)
Heat • A measure of the amount of energy
transferred – Measured in Joules
• Flows from HOT TO COLD
• Particles at the same temperature have the same average kinetic energy
Temperature
• New Unit = Kelvin (K)
• A change of 1oC = a change of 1 K
• K = oC + 273
• Freezing Point of water = 0oC = 273 K
Measuring Heat
• Q = mC∆T
• Q = heat (in Joules)
• m = mass of the substance
• C = specific heat of the substance
• ∆T = change in temperature (final – initial)
• C for water = 4.18 J/gK
– On reference tables (they’ll give you others if needed)
Starting off easy
• How many Joules are absorbed when 50.0g of water are heated from 30.2 oC to 58.6oC?
• How many Joules are required to heat 100g of water 10oC?
A little bit harder now
• How much heat must be absorbed by 375 grams of water to raise its temperature by 25° C?
• What mass of water can be heated from 25.0° C to 50.0° C by the addition of 2825 J?
• What is the final temperature when 625 grams of water at 75.0° C loses 7.96 x 104 J?
Challenge Problems
• Hint: Remember the Law of Conservation • A copper cylinder has a mass of 76.8 g and a
specific heat of 0.092 cal/g·C. It is heated to 86.5° C and then put in 68.7 g of turpentine whose temperature is 19.5° C. The final temperature of the mixture is 31.9° C. What is the specific heat of the turpentine?
• A 65.0 g piece of iron at 525° C is put into 635 grams of water at 15.0° C. What is the final temperature of the water and the iron? Specific heat of iron is 0.450 J/gK
More practice if needed
• Find the amount of heat (Q) needed to raise the temperature of 5.00 g of a substance from 20.0o C to 30.0oC if the specific heat of the substance is 2.01 J/goC.
• A metal with a specific heat of 0.780 J/goC requires 45.0 J of heat to raise the temperature by 2.00oC. What is the mass of the metal?
A few more
• A substance requires 50.0 J of heat to raise its temperature by 6.00oC. If the mass of the substance is 5.00 g, what is the specific heat of the substance?
• A metal with a specific heat of 0.70 J/goC and a mass of 8.00 g absorbs 48.0 J of heat. What will be the temperature change of the metal?
• 12/2 Chemistry
• Unit 4 – Physical Behavior of Matter
• Aim: How can we calculate heat?
• Obj: SWBAT calculate heat transfers
• Do now: A substance requires 50.0 J of heat to raise its temperature by 6.00oC. If the mass of the substance is 5.00 g, what is the specific heat of the substance?
• Homework: Worksheet (due tomorrow)
• Homework: Test Corrections (due Friday)
• 12/3 Chemistry
• Unit 4 – Physical Behavior of Matter
• Aim: How can we calculate heat at phase changes?
• Obj: SWBAT calculate heat transfers
• Do now: A metal with a specific heat of 0.70 J/goC and a mass of 8.00 g absorbs 48.0 J of heat. What will be the temperature change of the metal?
• Homework: Worksheet (due tomorrow)
• Homework: Test Corrections (due Friday)
• Whenever a substance undergoes a temperature change, use q =mC∆T
• But why can’t we use this to solve for the amount of heat required to boil or melt a substance ?
• Hint : Think about the heating/cooling curves.
• During the melting and boiling temperature is constant so ∆T=0
• New idea : use a substance’s Heat of Fusion and heat vaporization
• Heat of Fusion = the amount of heat needed to convert a substance from solid to liquid at its melting point
• Heat of vaporization = the amount of heat required to convert a substance from liquid to gas at its boiling point
• Heat of fusion
Q = mHf
• Heat of vaporization
Q = mHv
Practice Problems
• How much energy would be required to melt 15.0 g of ice at 0 oC?
• How much energy would it take to boil 36.0 g of water at 100 oC?
• If 123g of H2O is boiled (from liquid to gas), how much heat energy is required?
• If 400 J is released when freezing (from liquid to solid) CO2, what is the amount of mass of CO2 that is frozen? (CO2 Heat of Fusion = 184 J/g
• 12/8 Chemistry
• Unit 4 – Physical Behavior of Matter
• Aim: How do gases behave?
• Obj: SWBAT calculate P, V, and T
• Do now:
• Calculate the energy released as 4008 grams of water freezes
• Calculate the energy required as 5000 grams of water boils (vaporizes).
• Homework: Gas Law Worksheets (on engrade)
Kinetic Molecular Theory (KMT)
• Gas particles are in CONSTANT, RANDOM, STRAIGHTLINE MOTION
• Gas particle collisions transfer energy perfectly (elastic collisions – no net loss of energy)
• Volume of gas particles is NEGLIGIBLE
• Gas particles don’t attract each other
Relationships
• Pressure and number of particles
– As the # of particles increases, so does the pressure
• Temperature and velocity
– As temperature increases, so does the velocity of gas particles
IMPORTANT MESSAGE
• WHEN DOING MATH PROBLEMS WITH
GASES, THE TEMPERATURE MUST BE IN
KELVIN
Boyle’s Law
• At constant Temperature, Pressure and Volume have an inverse relationship (as one increases, the other decreases)
Charles’ Law
• At constant Pressure, Volume and Temperature are directly proportional. (As one increases, so does the other)
Combined Gas Law
• Combines the effects of Pressure, Temperature, and Volume.
• If one of the variables is constant, you can leave it out of the equation.
Ideal vs Real Gas
• KMT describes ideal gases
• Most ideal gas = Hydrogen or Helium
• Gases act most ideal in conditions of HIGH TEMPERATURE AND LOW PRESSURE
• However, real gases
– Sometimes do attract each other during extreme conditions
– Do occupy volume (especially important at high P)
• 12/8 Chemistry
• Unit 4 – Physical Behavior of Matter
• Aim: How do gases behave?
• Obj: SWBAT calculate P, V, and T
• Do Now: Rearrange the combined gas law to solve for T2
• Homework: Gas Law Worksheets (on engrade)
Avogadro’s Hypothesis
• When the volume, temperature, and pressure of two gases were the same, they contained the same number of molecules
• You’re probably going to forget this one, everyone always does.
• Poor Avogadro
Practice Problems
• If a gas at 25.0 °C occupies 3.60 liters at a pressure of 1.00 atm, what will be its volume at a pressure of 2.50 atm?
• A gas occupies 1.56 L at 1.00 atm. What will be the volume of this gas if the pressure becomes 3.00 atm?
More Practice
• 4.00 L of a gas are under a pressure of 6.00 atm. What is the volume of the gas at 2.00 atm?
• A sample of gas has a volume of 12.0 L and a pressure of 1.00 atm. If the pressure of gas is increased to 2.00 atm, what is the new volume of the gas?
Even More Practice
• A sample of gas has a volume of 12.0 L and a pressure of 1.00 atm. If the pressure of gas is increased to 2.00 atm, what is the new volume of the gas?
• A sample of gas has a volume of 12.0 L and a pressure of 1.00 atm. If the pressure of gas is increased to 2.00 atm, what is the new volume of the gas?
The limit does not exist to the practice!
• If I initially have a gas at a pressure of 12.0 atm, a volume of 23.0 liters, and a temperature of 200.0 K, and then I raise the pressure to 14.0 atm and increase the temperature to 300.0 K, what is the new volume of the gas?
• A gas takes up a volume of 17.0 liters, has a pressure of 2.30 atm, and a temperature of 299 K. If I raise the temperature to 350.0 K and lower the pressure to 1.50 atm, what is the new volume of the gas?
Who said I didn’t give practice?
• A gas has a temperature of 14 0C, and a volume of 4.5 liters. If the temperature is raised to 29 0C and the pressure is not changed, what is the new volume of the gas?
• If I have 17.0 liters of gas at a temperature of 67.0 0C and a pressure of 88.89 atm, what will be the pressure of the gas if I raise the temperature to 94.0 0C and decrease the volume to 12.0 liters?
Because they were wrong
• I have an unknown volume of gas at a pressure of 0.500 atm and a temperature of 325 K. If I raise the pressure to 1.20 atm, decrease the temperature to 320.0 K, and measure the final volume to be 48.0 liters, what was the initial volume of the gas?
• If I have 21.0 liters of gas held at a pressure of 78.0.0 atm and a temperature of 900.0 K, what will be the volume of the gas if I decrease the pressure to 45 atm and decrease the temperature to 750.0 K?
Very wrong
• If I have 2.9 L of gas at a pressure of 5.0 atm and a temperature of 50.0 0C, what will be the temperature of the gas if I decrease the volume of the gas to 2.4 L and decrease the pressure to 3.0 atm?
• I have an unknown volume of gas held at a temperature of 115 K in a container with a pressure of 60.0 atm. If by increasing the temperature to 225 K and decreasing the pressure to 30.0 atm causes the volume of the gas to be 29 liters, how many liters of gas did I start with?
Get excited for your Christmas Break work…
• Helium in a 100 mL container at a pressure of 66.6 kPa is transferred to a container with a volume of 250 mL. What is the new pressure if no change in temperature occurs? What is the new pressure if the temperature changes from 210oK to 151oK?
• What will have to happen to the temperature of a sample of methane if 1000 mL at 98.6 kPa and 25oC is given a pressure of 108.5 kPa and a volume of 900 mL?
• 12/9 Chemistry • Unit 4 – Physical Behavior of Matter • Aim: How do we separate mixtures? • Obj: SWBAT explain how to separate different
types of mixtures • Do Now: A child has a toy balloon with a
volume of 1.80 liters. The temperature of the balloon when it was filled was 20° C and the pressure was 1.00 atm. If the child were to let go of the balloon and it rose 3 kilometers into the sky where the pressure is 0.667 atm and the temperature is -10° C, what would the new volume of the balloon be?
• Homework: packet
Filtration
• Used to separate solids and liquids
• Residue is what remains on the filter
• Filtrate is what passes through
Gravity
• If liquids are immiscible (don’t dissolve) their difference in density can separate them
Distillation
• Separates miscible (dissolved) liquids with different boiling points
• Used for gasoline
• Used for alcohol
Chromatography
• Separates components of mixture based on attraction to other substances.
• 12/11 Chemistry
• Lab
• Aim: How can we graphically represent periodic trends?
• Obj: SWBAT graph periodic trends
• Do Now: How is the modern periodic table arranged?
• Homework: STUDY
• 12/15 Chemistry
• Test
• Aim: How can we get 100% (while maintaining academic integrity of course)?
• Obj: SWBAT Answer Regents Style Questions
• Do Now: Clear Desk