chemistry topic 4 - physical behavior of matter

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


• 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


• Aim: How can we calculate heat?


• 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


• Aim: How can we calculate heat at phase changes?


• 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


• 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


• 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



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

chemistry topic 4 - physical behavior of matter

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