Physical Behavior of Matter

Physical Behavior of Matter

Unit Vocabulary: Absolute Zero Avogadro’s Law Normal Boiling Point Compound Cooling Curve Deposition Energy Element Evaporation Heat Heat of Fusion Heat of Vaporization Heating Curve Heat Transfer Kinetic Energy Kinetic Molecular Theory (KMT) Lattice Matter Mixture Melting Point Potential Energy Sublimation Temperature Vapor Pressure

PBOM Part 1 Important Terms

Energy and Temperature definitions: Energy: CAPACITY to do WORK (ability of MATTER to do WORK) Kinetic Energy (KE): energy of MOTION/MOVEMENT associated with TEMPERATURE change Potential (AKA Phase) Energy: energy of POSITION (STATIONARY or STORED energy) associated with PHASE change, NOT TEMPERATURE change

Temperature: measure of the AVERAGE KINETIC ENERGY of a substance’s particles (Δ TEMP means Δ KE); does NOT depend on SAMPLE SIZE; measured in ºC, ºF, or K

Heat: quantity of ENERGY , that is the energy transferred between systems, when they are at different temperatures. Cannot be measured directly (as opposed to temperature) Can only be measured as it’s TRANSFERRED from one (HOTTER) object to another (COOLER) object DOES depend on SAMPLE SIZE (the larger the sample, the more heat needed to bring it to desired temp) Measured in JOULES (J), KILOJOULES (kJ) or CALORIES (we will only use J or kJ in this class) NOTE: Although there is a DIRECT RELATIONSHIP between TEMPERATURE and HEAT, they are NOT THE SAME THING!!!

Temperature Scales: There are three common temperature scales: 1. Fahrenheit (ºF) 2. Celsius (ºC) 3. Kelvin (K) As chemists we use two of these scales: ºC and K ABSOLUTE ZERO -273ºC or 0 K; the temperature at which all PARTICLE MOTION ceases

The thermometer scales are calibrated by two fixed positions: 1) The freezing/melting point of water 0ºC or 273 K 2) 2) The boiling point of water 100ºC or 373 K NOTE: There is a DIRECT CORRELATION between the KELVIN and CELSIUS scale which is what makes it very easy to convert from one to the other. They are to the same scale, only shifted. 3) A change of 1ºC is the same as a change of 1 K. Or, in equation form: Δ 1ºC Δ 1 K

Kelvin/Celsius Temperature Conversions: 1) What Kelvin temperature is equivalent to 35 ºC? 308 K 2) The classroom has a temperature of 21ºC, what is the temperature of the classroom in Kelvin? 294 K

3) When the temperature is 300K, what is the temperature in degrees Celsius? (Note: you must rearrange the formula!) 27ºC 4) If something has a temperature of 5 K, what is this in ºC? -268ºC 5) A sample is heated and rises in temperature by 12ºC. What is this temperature difference in Kelvin? ΔT 12 K

Additional Questions to Ponder: 1. Different masses of copper and iron are found to have the same temperature. Compare the average kinetic energy of the copper atoms to the iron atoms. Explain your answer. 2. A student is examining two samples of ice. Sample A has a mass of 10 g while sample B has a mass of 1 g. Both samples are at their freezing point. Compare and contrast the two samples in terms of temperature and heat energy. 3. For the following scenarios, please indicate whether the average kinetic energy of water molecules is increasing, decreasing, or remaining the same. a) H2O(s) changes to H2O(l) at 0 C: Ans: b) H2O(l) changes to H2O (s) at 0 C: Ans: c) H2O(l) at 10 C changes to H2O(l) at 20 C: Ans: d) H2O(l) at 20 C changes to H2O(l) at 10 C: Ans: 4. When the temperature of an object changes by 100 C, how much does it change in Kelvin? 5. What are the two fixed points on the thermometer (please state the names and temperature values for both? 6. When you look at a solid, it does not seem to be moving at all. Since the particles are not at absolute zero, explain how it is possible for the particles to be moving. 7. A temperature probe in a plant reads -298 C. Is this temperature possible? Explain.

PBOM Part 2 Phases of Matter

Phases of Matter: We are concerned with only 3 phases. Matter exists in three forms at STP (Standard Temperature & Pressure) *See Table A 1. SOLID (s) 2. LIQUID (l) 3. GAS (g) 4. PLASMA ionized gas (we’re not concerned with this phase) *AQUEOUS A SOLID DISSOLVED IN WATER (SOLUTION) (This is a STATE, but not a PHASE)

Solidify –liquid to solid Melt – solid to liquid Deposit –gas to solid Sublime – solid to gas Vaporize – liquid to gas Condense – gas to liquid

http://www.harcourtschool.com/activity/states of matter/

PBOM Part 3 Phase Change Diagrams or Heating & Cooling Curves

Heating Curves: Temperature vs. Time is graphed while a substance is being heated at a constant rate. Y-axis- Temperature X-axis – Time

While Kinetic Energy (KE) changing Potential Energy (PE) stays the same. This is when the temperature changes. Pts A to B and C to D

While Potential Energy (PE) changing Kinetic Energy (KE) stays the same. This is when the temperature stays the same. Pts B to C and D to E

Cooling Curves: Temperature vs. Time is graphed while a substance is being cooled at a constant rate.

Fill in the chart using the heating curve above.

Phase Changes are classified as ENDOTHERMIC or EXOTHERMIC. ENDOTHERMIC system absorbs or takes in heat energy EXOTHERMIC system gives off heat energy

Use the graph below to answer the questions that follow:

At what temperature will this substance boil? At what temperature will this substance become a liquid? Between 55oC and 90oC, the kinetic energy of the substance is At 90oC, the potential energy of the substance is

Exothermic system RELEASES or GIVES OFF heat energy ExamplesFREEZING & CONDENSATION

ENDOTHERMIC system ABSORBS or GAINS heat energy ExamplesMELTING & BOILING

PBOM Heat Calculations (Temperature Change) Part 4

Measurement of Heat Energy: HEAT Energy transferred due to a difference in temperatures (can only be measured as it is transferred from a warmer substance to a cooler substance) The amount of heat LOST or GAINED in a physical or chemical reaction can be calculated using the following equation (found in Table T): q mcΔT q heat (units Joules or J) m mass of sample c heat capacity of sample (see Table B for H2O) ΔT change in temperature

Example 1: How many joules are absorbed when 50.0 g of water are heated from 30.2 C to 58.6 C? q m c ΔT How many joules we are looking for q Define the variables!

Practice Problems: 1. What is the specific heat of silver if a 93.9 g sample cools from 215.0 C to 196.0 C with the loss of 428 J of energy?

2. If 100.0 J are added to 20.0 g of water at 30.0 C, what will be the final temperature of water?

3. The temperature of a sample of water in the liquid phase is raised 30.0 C by the addition of 3762 J. What is the mass of water?

PBOM Heat pf Fusion & Vaporization Part 5

Heat of Fusion (Hf): the amount of heat (or PE) required to change a substance from a solid to a liquid (see Table B) Heat of Fusion Equation (see Table T): q mHf Example: How many joules are required to melt 255 g of ice at 0 C? q ? Hf 334J/g m 225g 334J/g x 255g 85,170 J or 8.52 X 104 J

Practice Problems: 1. What is the total number of kilojoules of heat needed to change 15.0 g of ice to water at 0 C? 2. In question 1 is heat being absorbed or released? Is this process endothermic or exothermic? 3. 1.0 x 105 J of heat is needed to melt ice at 0 C, what was the mass of the sample?

Heat of Vaporization: the amount of heat required to change a substance from a liquid to a gas (see Table B) Heat of Vaporization Equation (see Table T): q mHv Example: How many kilojoules of energy are required to vaporize 423 g of water at 100 C?

1. What is the total number of kilojoules required to completely boil 100. g of water at 100 C. 2. At 1 atmosphere of pressure, 25.0 g of a compound at its normal boiling point are converted to a gas by the addition of 34,400 J. What is the heat of vaporization for this compound?

A device known as a BOMB CALORIMETER can be used to measure the amount of heat given off in a reaction. The reaction takes place in the reaction chamber and the heat released by the reaction is absorbed by the surrounding water. The HEAT given off by the reaction can be calculated by measuring the TEMPERATURE INCREASE of the WATER.

PBOM Part 6 Solids & Liquids

Liquids - the phase of matter characterized by its constituent particles appearing to vibrate about moving points. (wiggle around) Evaporation: the process by which surface particles of liquids escape into the vapor phase. Boiling is not Evaporation!! Can a liquid evaporate if its temperature is below the normal boiling point? Yes, any liquid can, mud puddles for example.

Vapor Pressure (Table H) : The UPWARD pressure exerted by a vapor in equilibrium with its liquid. What happens if the vapor pressure of a liquid is equal to the atmospheric pressure? This is a phase equilibrium and the liquid will boil. So this is the boiling point of that liquid. Boiling pt means particles from anywhere in the sample In the liquid can turn to a gas.

Table H is used to represent the relationship between Temperature on the x-axis and Vapor Pressure on the y-axis. It allows us to establish the normal boiling pt (STP). 101.3 kPa or 1 atm is standard pressure. So with this information you can find the normal boiling pt temp. Just follow the dotted line across at 101.3 kPa So what is water's BP? 100 degrees Celsius.

You can also find the boiling point at a different pressure. What vapor pressure will water boil at if it was to boil at 50 degrees Celsius? The pressure would have to be lowered to 12kPa

Solid: the phase of matter characterized by particles that appear to VIBRATE about FIXED POINTS. As the TEMPERATURE of a liquid is LOWERED, the FORCES OF ATTRACTION (IMF'S) between the particles become STRONGER because they are closer and moving slower. Attractive forces ARRANGE particles in an ORDERLY fashion The MOTION of the particles becomes severely RESTRICTED (particles VIBRATE in place)

The temperature at which a substance becomes a solid is its MELTING POINT (m.p.) or FREEZING POINT (f.p.) All true solids have a structure called a CRYSTAL LATTICE meaning particle arrangement is regular and geometric.

PBOM 7 Ideal Gases

Gases Kinetic Molecular Theory (KMT): A MODEL USED TO EXPLAIN THE BEHAVIOR OF GASES IN TERMS OF THE MOTION OF THEIR PARTICLES

Ideal gas is a great way to think about how gases behave. It is not real, but helpful to understand gases!

Major Assumptions of KMT: 1. The VOLUME of the GAS PARTICLE is so small it is NEGLIGIBLE in comparison to the VOLUME of the CONTAINER in which it is confined. 2. The gas particles DO NOT ATTRACT each other (NO IMF’s)

3. The COLLISIONS BETWEEN THE GAS PARTICLES and WITH THE WALLS OF THE CONTAINER are ELASTIC (no energy lost) 4. The gas particles move in RANDOM, CONTINUOUS, STRAIGHT-LINE motion.

An IDEAL GAS is THEORETICAL and is used to PREDICT the behavior of REAL GASES (O2, H2, He, etc.) KMT is based on Ideal gases The assumptions are not true of REAL GASES

Problems for KMT: o LARGE MOLECULES/ATOMS (big particles have high IMF’s) o SLOW movements are subject to more IMF’s o SMALL VOLUME containers mean MORE COLLISIONS

Real gases follow KMT best under the following conditions: o LOW IMF’s (NONPOLAR) o LOW PRESSURE (HIGH VOLUME) o HIGH TEMPERATURE (FAST MOVING) o SMALL SIZE An Ideal gas is likes kids in the summer! Low pressure and High temperatures!

What are the two most ideal gases on the planet? Explain The real gases that behave the most ideal.

PBOM Part 8 Gas Laws

Collision Theory: In order for a reaction to occur, particles must COLLIDE with the proper amount of ENERGY and with the proper ANGLE and POSITION.

Gas Laws: Avogadro’s Law: GASES at the same TEMPERATURE, PRESSURE, & VOLUME have the same number of MOLECULES or PARTICLES 1. Which one has more gas particles? Explain. :They have the same amount because they are at the same STP 2. Which one will behave the most ideally? Explain. Hydrogen because it is the smallest. 3. Which one has the most atoms? Explain. CO2 because it has the most atoms per molecule.

Combined Gas Law: (use for GASES ONLY when all THREE VARIABLES for a gas are CHANGING – nothing remains constant in this type of problem) From Reference Table T: **NOTE: You MUST use Kelvin (not ºC) for the calculation to work!

Sample Problem 1: A gas has a volume of 100. mL at a temperature of 20.0 K and a pressure of 760. mmHg. What will be the new volume if the temperature is changed to 40.0 K and the pressure to 380. mmHg?

Sample Problem 2: An ideally behaving gas occupies 500. mL at STP. What volume does it occupy at 546 K and 980. KPa?

When either P, T, or V is held constant for a gas: Boyles Law (Constant Temperature): Example: The volume occupied by a gas at STP is 250 L. At what pressure (in atm) will the gas occupy 1500 L, if the temperature is constant? P2 0.167 atm Example: decreasing P on marshmallow will increase V

*Both Avogadro’s Law and the Kinetic Molecular Theory can be used to explain the relationship between pressure, temperature, and volume of a gas. Here’s an easy way to remember the relationship between pressure, temperature, and volume. At the top of the next page, you’ll see the a large “P T V” (NOTICE how they are written from left to right in alphabetical order). Place your finger on whatever variable remains constant, then rotate the variable you want to change up or down. Watch what happens to the third variable as a result.

Charles Law (Constant Pressure): Example: The volume of an ideally behaving gas is 300 L at 227 C. What volume will the gas occupy at 27 C when pressure remains constant? V2 35.7 L

Example 2: Aerosol cans with gases under high pressure can’t be near high temp or contents will expand and the bottle will explode or bag s of chips in cars on hot summer days.

Gay Lussac’s Law (Constant Volume) Example: The pressure exerted by an ideally behaving gas is 700 KPa at 200 K. What pressure does the gas exert at 500 K when volume remains constant? P2 1750 kPa

Some Gas Law Problems to Try: 1. A gas has a volume of 100 mL at a temperature of 20. K and a pressure of 760 mm Hg. What will be the new volume when the temperature is changed to 40.0 K and the pressure is changed to 380 mm Hg? 2. The volume of a sample of a gas at 273 C is 200.0 L. If the volume is decreased to 100.0 L at constant pressure, what will be the new temperature of the gas?

3. What will be the new volume of 100. mL of gas if the Kelvin temperature and the pressure are both doubled? 4. A gas occupies a volume of 400. mL at a pressure of 330. torr and a temperature of 298 K. At what temperature will the gas occupy a volume of 200. mL and have a pressure of 660. torr?

Dalton’s Law of Partial Pressure: in a mixture of GASES, the TOTAL PRESSURE of the mixture is the SUM of the PARTIAL PRESSURES of each component gas.

Example: The total pressure of three gas components in a mixture is 550 torr. If the pressure of gas A is 200 torr and the pressure of gas B is 75 torr, what is the partial pressure of gas C? Gas C 275 torr

Partial Pressure Problems: 1. A mixture of oxygen, nitrogen, and hydrogen gases exerts a total pressure of 74.0 kPa at 0ºC. The partial pressure of the oxygen is 20.0 kPa and the partial pressure of nitrogen is 40.0 kPa. What is the partial pressure of hydrogen in this mixture? 2. A cylinder is filled with 2.00 moles of nitrogen, 3.00 moles of argon, and 5.00 moles of helium. If the gas mixture is at STP, what is the partial pressure of the argon? 3. If 4.00 moles of oxygen gas, 3.00 moles of hydrogen gas, and 1.00 moles of nitrogen gas are combined in a closed container at standard pressure, what is the partial pressure exerted by the hydrogen gas?

DENSITY: the quantity of matter in a given unit of volume D mass/volume Take a look at the two boxes below. Each box has the same volume. If each ball has the same mass, which box would weigh more? Why? Ans: The box on the left would weigh more because it has more balls in the same amount of space.

The box that has more balls has more MASS per unit of VOLUME. This property of matter is called density. The density of a material helps to distinguish it from other materials. Since mass is usually expressed in grams and volume in cubic centimeters, density is expressed in grams/cubic centimeter (g/cm3).

P T V a. If PRESSURE DECREASES at CONSTANT TEMPERATURE, the VOLUME INCREASES. b. If TEMPERATURE INCREASES at CONSTANT PRESSURE, the VOLUME INCREASES. c. If TEMPERATURE INCREASES at CONSTANT VOLUME, the PRESSURE INCREASES. *Does this all sound logical?