State Changes Heat of Fusion Heat energy required to convert a solid at its melting point to a liquid Value for water: 333 J/g Heat of Vaporization Heat.

Slides:

Advertisements

Similar presentations

Section 7.3—Changes in State

Advertisements

White Board Practice Problems © Mr. D. Scott; CHS.

Topic B Work, Calorimetry, and Conservation of Energy

Matter & Energy Ch. 13. Solid Have a definite shape and volume Particles have strong attractive force, but still vibrate.

What happens to thermal (heat) energy? When objects of different temperature meet: Warmer object cools Cooler object warms Thermal energy is transferred.

 MOLAR HEAT: it is the enthalpy changes(ΔH) for 1 mole of substance to change a state.  Molar Heat of Fusion (ΔH fus ): the amount of heat absorbed.

Change of state. Change of state and energy consumption.

Aim: How to measure energy absorbed during a phase change

Changes of State.

WHAT ARE SOME OF THE WAYS THAT HEAT ENERGY CAN BE TRANSFERRED? 1) CONDUCTION – IF TWO OBJECTS ARE IN CONTACT, THERMAL ENERGY CAN BE TRANSFERRED THROUGH.

Calculations in Chapter 10. Molar Enthalpy of Fusion Used when melting or freezing = ___energy ____ mol of substance Can be arranged to find any of the.

 Energy is transferred ◦ Exothermic – heat is released  Heat exits ◦ Endothermic – heat is required or absorbed by reaction  Measure energy in Joules.

How many joules are needed to change 120.g of

Phase Changes What did one water molecule say to another water molecule about vapor? Don’t worry it’s just a phase he’ll cool down.

Phase Changes Melting Vaporization Condensation Freezing Sublimation.

Heating and Cooling Curve Definitions: Specific Heat: Amount of energy required to raise the temperature of 1 gram of a substance by 1⁰ Celsius Enthalpy.

 Energy (heat) may be expressed in joules or calories.  1 calorie (cal) = joules (J)  How many joules in 60.1 calories?  How many calories.

Practice Energy Calculation Quiz. How much energy does it take to convert 722 grams of ice at  211  C to steam at 675  C? (Be sure to draw and label.

For this heating curve, energy was added at a constant rate. This is obvious in regions where the temperature steadily increases (AB ; CD ; EF). In these.

Calorimetry How to use math to describe the movement of heat energy Temperature Change Problems Temperature Change Problems Phase Change Problems Phase.

Warmup 1) Solve for x 689 = (1.8)(x)(45.2 – 27.4) 689 = (1.8)(x)(17.8) 2) On a hot summer afternoon, you get into the car, and it’s unbearably HOT inside!

Phase Changes Section 17.3 in YOUR book.

Temperature ( o C) Heat (J) Solid Liquid Gas Heat = mass x ΔT x C l Heat = mass x H Fusion Heat = mass x H Vaporization s ↔ l l ↔ g H Vaporization H Fusion.

Calculating Heat. Specific Heat Amount of heat energy needed to raise the temp of 1 ml of a substance 1°C For water the specific heat is 4.19 J/g °C,

Chapter 1.4.2: Temperature in Thermal Systems

NOTES: 17.3 – Heat in Changes of State. RECALL… ● when a substance changes state (i.e. melts, freezes, vaporizes, condenses) it does not change temperature.

Heat: Phase Change. 'change of phase' 'change of state'. The term 'change of phase' means the same thing as the term 'change of state'. o These changes.

Heat in Changes of State

Part One Heat and Temperature.

Calorimetry How to use math to describe the movement of heat energy Temperature Change Problems Temperature Change Problems Phase Change Problems Phase.

Heating & Cooling Curves A STEP BY STEP PRACTICE PROBLEM © Mr. D. Scott; CHS.

Heat & Changes of State. Changes of State Solid to liquid Solid to liquid Liquid to solid Liquid to solid Liquid to gas Liquid to gas Gas to liquid Gas.

Phase Changes and Thermochemistry

PHASE CHANGE GRAPH ( ) Tro's Introductory Chemistry, Chapter 12 1.

Changes of State. Is the change of a substance from one physical form to the other All changes of states are physical changes, this means that the identity.

Temp ( o C) Phase Change Diagram Practice Use the following graph of Temperature vs. Heat for 10 g of compound “X” to answer the questions: 500.

Heating Curves. Energy and Phase Change When adding heat to a solid, energy added increases the temperature and entropy until the melting point is reached.

Section 7.3—Changes in State What’s happening when a frozen ice pack melts?

Thermochemistry Enthalpy: change in heat. Energy and Change of State You do not have to write this When energy is added to a solid substance, its temperature.

States of Matter.

Phase Change Problems.

Changes of State Melting Freezing Vaporization Condensation.

Section 3.3 Phase Changes.

Phase Changes Notes on 3.3 Temperature  Temperature will not change during a phase change.  Once a substance reaches the temperature required for a.

6.4 States of Matter & Changes of State The three states of matter are: solid, liquid, gas. A change of state requires a change in the thermal energy of.

Thermochemistry Part 4: Phase Changes & Enthalpies of Formation.

Reaction Energy.

Thermochemical Calculations

Bellringer What would happen to the particles of a substance if it were cooled to absolute zero? In other words, how would they behave? 2.Do.

Energy Changes & Phase Changes. It takes energy to heat stuff up! For pure substance in single phase, can calculate how much using Q = mC  T For pure.

Energy and Phase Changes. Energy Requirements for State Changes To change the state of matter, energy must be added or removed.

EXPLAINING A HEATING CURVE FOR ICE, WATER & STEAM

Energy Changes & Phase Changes Heating & Cooling Curves.

Melting Solid  Liquid Energy is added, particles speed up (endothermic) Melting Point: Temp. at which a substance melts Freezing Liquid  Solid Energy.

Energy Changes & Phase Changes Heating & Cooling Curves.

Calculating Heat During Change of Phase Heat Added (J)

Reaction Energy Specific Heat u The specific heat of any substance is the amount of heat required to raise the temperature of one gram of that substance.

Aim: How to measure energy absorbed during a phase change DO NOW: 1. A g piece of iron absorbs joules of heat energy, and its temperature.

What types of materials have low specific heats? What are some advantages/disadvantages to this? What types of materials or substances have high specific.

11.3 Heat in Changes of State. Warm up Is it exo- or endothermic???? -negative ΔH -positive ΔH -Heat as a reactant -Heat as a product -Combustion of.

REVIEW 1.Write a formula for the freezing of water. 2.Write a formula for the boiling of water. 3.Write a formula for the condensing of water. 4.Write.

SPECIFIC LATENT HEAT. Objective At the end of this lesson, you should be able to : At the end of this lesson, you should be able to : State that transfer.

Ch Solids & Phase Changes. Solids The particles of a solid are more closely packed than those of a liquid or gas. Intermolecular forces between.

Phase Changes Notes 3.3.

PHASE CHANGES Each state of matter is called a PHASE

Energy Transfer and Thermal Equilibrium

Is the process by which the substance changes from solid to liquid.

Heat Exchange During Physical Changes

Changes of State Chapter 3 Section 3.

Changes of State units: J/g Heat of Vaporization

Presentation transcript:

State Changes Heat of Fusion Heat energy required to convert a solid at its melting point to a liquid Value for water: 333 J/g Heat of Vaporization Heat energy required to convert a liquid at its boiling point to a solid Value for water: 2260 J/g

endothermic process (H positive) Vaporization endothermic process (H positive) Condensation exothermic process (H negative) Melting endothermic process (H positive) Freezing exothermic process (H negative)

Finding the Energy to Change the State of a Given Mass of a Substance - Pause the video and solve the problems below. J = (mass)(heat of vaporization or heat of fusion) Find the heat energy needed to change 50.0 g of water from liquid to gas. How much heat energy will be released when 50.0 g of water freeze (change from liquid to solid)?

Finding the Energy to Change the State of a Given Mass of a Substance - Pause the video and solve the problems below. J = (mass)(heat of vaporization or heat of fusion) Find the heat energy needed to change 50.0 g of water from liquid to gas. (2260J/g)(50.0g) = 1.13 x 106 J How much heat energy will be released when 50.0 g of water freeze (change from liquid to solid)? (-333J/g)(50.0g) = -1.67 x 105 J

Graphing Temperature v. Time During a State Change 120 Temperature (C) -10 Time (min)

Why do the plateaus occur in this graph even though heat was steadily added over time?

Cpgas = 1.86 J/gK Heat of vaporization = 2260J/g Specific heat of water = 4.184J/gK heat of fusion = 333 J/g Specific heat of ice = 2.06 J/gK

Pause the video while you solve the problem. Find the energy needed to convert 500.g of ice at -50.0 C to steam at 200. C. Pause the video while you solve the problem. Solve this in 5 steps by finding energy needed to: Heat ice from -50.0 to 0 using specific heat of ice Melt ice using heat of fusion of ice Heat water from 0 to 100 using specific heat of water Boil water using heat of vaporization of water Heat steam from 100 to 200. using specific heat of steam Then add all of these q values together to find the total amount of energy needed.

Pause the video while you solve the problem. Find the energy needed to convert 500.g of ice at -50.0C to steam at 200. C. Pause the video while you solve the problem. Solve this in 5 steps by finding energy needed to: Heat ice from -50.0 to 0 using specific heat of ice q = (2.06J/gK)(50.0g)(0 C - -50.0C) = 5.15 x 104J Melt ice using heat of fusion of ice q = (333J/g)(50.0g) = 1.67 x 105J Heat water from 0 to 100 using specific heat of water q = (4.184J/gK)(50.0g)(100 C - 0C) = 2.09 x 105J Boil water using heat of vaporization of water q = (2260J/g)(50.0g)= 1.13 x 106J Heat steam from 100 to 200. using specific heat of steam q = (1.86J/gK)(50.0g)(200. C – 100.0C) = 9.30 x 104J Then add all of these q values together to find the total amount of energy needed. 1650kJ

Let’s try something harder!!! Pause the video while you solve the problem. Suppose you pour 250. mL of tea (density 1g/mL) at 18.2C into a glass with 5 ice cubes (each weighing 15g). What quantity of ice will melt and what mass will remain? (Hint: the tea will cool until it is at thermal equilibrium with the ice at 0 C.) Assume the specific heat of tea is 4.2J/gK.