Transcript Thermochemistry - Warren County Schools

Chem II: 1.28.16
Due:
• Thermochemistry Review Worksheet
Objectives:
•Review basic thermochemistry concepts.
(qualitatively and quantitatively)
Chem II: 2.01.16
Objectives:
• Complete Acid-Base Chemistry Exam
•Review basic thermochemistry concepts.
(qualitatively and quantitatively)
Thermochemistry Review
Primary Phase Changes
Chem II: 2.04.16
Due:
• Thermochemistry Review Worksheet
Objectives:
•Review basic thermochemistry concepts.
(qualitatively and quantitatively)
Thermochemistry Review
Thermochemistry Review
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Kinetic vs. Potential Energy
Kinetic Molecular Theory applications
Temperature vs. Kinetic Energy
Endothermic vs. Exothermic Processes
Energy Equation: Q= mc T
Thermochemistry
• Study of energy changes between matter during a
physical or chemical change.
• What are the two types of energy?
Thermochemistry
• Study of energy changes between matter during a
physical or chemical change.
• What are the two types of energy?
-Potential Energy= stored energy, energy in chemical
bonds
-Kinetic Energy = energy of motion; particle
movement during physical or chemical changes.
Heat Energy
Heat Energy:
• Energy that is transferred between matter of
different temperatures.
• Heat energy is also called kinetic energy.
• Units for Energy: Joules (J) or calories (cal)
• Energy does not have mass or volume, therefore it
is NOT classified as matter.
• How does heat energy flow between objects of
different temperatures?
Heat Energy Flow
Energy flows between:
• The System:
The matter you are studying/measuring.
• The Surrounding :
The matter (environment) around the system.
Energy Processes:
• Endothermic Process:
When more heat is absorbed by the system.
• Exothermic Process:
When more heat is released by the system.
Energy Diagrams
Energy Diagrams
Conservation of Matter and Energy
Matter:
•Matter undergoes
changes, but the atoms are
conserved.
Energy:
•Energy is also conserved during
changes.
•If energy increases for a system,
then its surroundings must
decrease in energy by the same
amount.
•1st Law of Thermodynamics
Energy Changes: Thermometer
•Energy changes between the system and its
surroundings can be measured using a thermometer.
•(Energy changes = Temperature changes)
•Temp. change indicates a change in speed of
particles of system or surroundings.
•Primary unit of measurement by scientists:
Celsius (oC) and Kelvin (K) scales
Thermometers
Visionlearning.com
K = oC + 273
Thermochemistry
The amount of energy transferred between matter
depends upon ..?
Thermochemistry
The amount of energy transferred between matter
depends upon the ..?
- chemical make-up of the matter
- the mass of the matter
- temperature difference between the matter
Specific Heats of Common Substances
Substances
Specific Heat
J/g* 0C
Specific Heat
cal/g*oC
water
4.18
1.00
Grain alcohol
2.4
0.58
ice
2.1
0.50
steam
1.7
.40
aluminum
0.90
0.21
silver
0.24
0.057
mercury
0.14
0.033
Energy Equation
Thermochemistry
1. What is thermochemistry?
2. Determine if the following changes represent an
endothermic or exothermic proccess.
a. making popsicles
b. evaporating water
c. sublimation of carbon dioxide
d. Sb + I2 + energy --------> SbI3
e. PCl3 + Cl2 ----------> PCl5 + energy
3. What is the 1st Law of Thermodynamics?
4. Is calorie, a unit of energy, the same calorie found in food?
5. What is specific heat capacity?
Energy Diagrams
Conservation of Matter and Energy
Matter:
•Matter undergoes
changes, but the atoms are
conserved.
Energy:
•Energy is also conserved during
changes.
•If energy increases for a system,
then its surroundings must
decrease in energy by the same
amount.
•1st Law of Thermodynamics
Heat Energy
Heat Energy:
• Energy that is transferred between matter of
different temperatures.
• Heat energy is also called kinetic energy.
• Units for Energy: Joules (J) or calories (cal)
• Energy does not have mass or volume, therefore it
is NOT classified as matter.
• How does heat energy flow between objects of
different temperatures?
-Always from hot to cold
Specific Heat Capacity
Specific Heat Capacity (c ):
The amount of heat needed to raise the temperature of a
one gram sample one Celsius degree (oC) or one Kelvin (K).
Energy Equation
Specific Heat Calculations
• The temperature of a 95.4 gram piece of copper
decreases from 48.0oC to 25.0oC when copper releases
849 Joules of heat. What is the specific heat of copper
in cal/goC?
Chem II: 2.22.16
Objectives:
•I can calculate and analyze energy calculations
during changes with matter.
Homework:
•Calorimetry Lab Report-due tomorrow
Thermochemistry Applications
Thermochemistry Quiz
1. What is the 1st Law of Thermodynamics
2. Using 3a. as a model, explain what a thermochemical
equation is.
3. Classify each as either endothermic or exothermic.
a. CaO (s) + H2O (l) ----> Ca(OH)2 (s) + 65.2 kJ
b. water condensing
c. (NH4)2CO3 ------> NH3 + CO2 + H2O
H= 150kJ
Chem II: 2.24.15
Due:
• Thermochemistry Review Packet
• Calorimetry Food Lab Pre-Lab Questions
Objectives:
•Review basic thermochemistry concepts.
• Thermochemistry Lab Preparations
Thermochemistry Review
• Energy Quiz!
Calorimetry Food Lab
Purpose:
To calculate the Calorie content in certain junk foods.
Junk Foods: Popcorn,
Pre-Lab:
• Read background and complete pre-lab questions.
Chem II: 2.25.15
Due:
• Calorimetry Food Lab Pre-Lab Questions
Objectives:
• Thermochemistry Lab
Homework:
• Calorimetry Lab Report(Purpose/Materials/Data)
Calorimetry Food Lab
Purpose:
To calculate the Calorie
content in certain junk foods.
Junk Foods:
• popcorn and nuts
• Do NOT use if melts/brittle.
Homework: *A MUST*
• Bring junk food and 12oz. can
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Chem II: 2.26.15
Objectives:
• Complete Thermochemistry Lab-No exceptions.
Homework:
• Calorimetry Lab Report-due Monday
Chem II: 2.26.15
Due:
• Calorimetry Food Lab Pre-Lab Questions
Objectives:
• Thermochemistry Lab
Homework:
• Calorimetry Lab Report-due Monday
Calorimetry Lab Report
• Goggles must worn at ALL times.
• Take careful measurements.
• Record quantitative AND qualitative
observations.
*Will be submitting a lab report.*
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Chem II: 3.4.15
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy calculations
during changes with matter.
Homework:
• Lab Report-Final Due Friday or Monday if out.
• Thermochemistry Equations Worksheet
Calorimetry Lab Report
• Lab Report Questions?
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Chem II: 3.9.15
Due:
• Calorimetry Lab Report
• Solar Energy Article Summary-place in tray
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy calculations
during changes with matter.
Calorimetry Lab Report
Lab
Group
Junk Food
Expt. Value
(Food Cal/g)
Actual Value
(Label)
(Food Cal/g)
% Error
1
2
3
4
5
6
7
9
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Calorimetry Lab Report
Thermochemistry
Chem II: 3.12.15
Due:
• Calorimetry Lab Report-due Wed.
• Solar Energy Article Summary-place in tray-Late
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy calculations
during changes with matter.
Calorimetry: Enthalpy Changes
Enthalpy Calorimetry Problems
When 25 mL of water containing 0.025 mol HCl at 25oC is
added to 25.0 mL of water containing 0.025 mol of Na(OH)
at 25oC in a foam calorimeter, a reaction occurs. Calculate
the enthalpy change in kJ during this reaction if the
highest temperature observed is 32oC. Assume the
densities of the solutions are 1.00g/mL and the specific
heat of water is 4.184 J/goC.
Enthalpy Calorimetry Problems
When 25 mL of water containing 0.025 mol HCl at 25oC is
added to 25.0 mL of water containing 0.025 mol of Na(OH)
at 25oC in a foam calorimeter, a reaction occurs. Calculate
the enthalpy change in kJ during this reaction if the
highest temperature observed is 32oC. Assume the
densities of the solutions are 1.00g/mL and the specific
heat of water is 4.184 J/goC.
Chem II: 2.17.16
Due:
• Calorimetry Lab Analysis/Conclusion Qsts.
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy calculations
during changes with matter.
Calorimetry Lab Report
Lab
Group
Junk Food
Expt. Value
(Food Cal/g)
Actual Value
(Label)
(Food Cal/g)
% Yield
1
2
3
4
5
6
7
9
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What is Enthalpy?
Chem II: 2.18.16
Due:
• Calorimetry Lab Analysis/Conclusion Qsts.
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy calculations
during changes with matter.
Enthalpy
• The amount of energy contained by a system at constant
pressure. (usually room temperature, 1atm)
•
H= The change in energy of a system during a reaction
occuring at constant pressure.
• Heat released or absorbed by system , Q
• Q=
•
H, at constant pressure
Thermochemical Equation
• What is a thermochemical equation?
Chem II: 2.19.16
Due:
• Heat of Reaction Practice Problems
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy calculations
during changes with matter.
•Lab Report due: Tuesday, February 23rd
Thermochemical Equations
• A chemical equation that includes the enthalpy
change.
1. CaO (s) + H2O(l) -----> Ca(OH)2 (s) + 65.2 kJ
CaO (s) + H2O(l) -----> Ca(OH)2 (s)
H = -65.2 kJ
2. 2Na(HCO3)(s) + 129kJ -----> Na2(CO3) (s) + H2O (l) + CO2 (g)
2Na(HCO3) (s) -----> Na2(CO3) (s) + H2O (l) + CO2 (g)
H= 129 kJ
H = heat of reaction
Thermochemical Equation
CaO (s) + H2O(l) -----> Ca(OH)2 (s)
H = -65.2 kJ
Heat of Reaction: ( H )
• The enthalpy change for a chemical reaction based
on the balanced equation at standard conditions.
• Standard temperature , 25oC (room temp.)
• Standard pressure, 1atm.
• Reactants/products states of matter must be at
room temperature.
• Enthalpy change depends upon moles of
substances in the reaction.
Heat of Reaction Calculations
Using the thermochemical equation below, calculate
the amount of heat in kJ required to decompose
2.24 mol Na(HCO3).
• 2Na(HCO3) (s) -----> Na2(CO3) (s) + H2O (l) + CO2 (g)
H= 129 kJ
Chem II: 2.23.16
Due:
• Calorimetry Lab Report
• Thermochemical Equations Practice Problems
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy changes during
chemical and physical reactions.
Thermochemical EquationsPractice Problems
Chem II: 2.23.16
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy changes during
chemical and physical reactions.
Enthalpy Changes in State
Enthalpy: Changes in State
• Molar heat of fusion :
• Molar heat of solidification :
• Molar heat of vaporization :
• Molar heat of condensation :
Enthalpy Changes in State
Enthalpy: Heat of Solution
Molar Heat of Solution: H(soln.)
• Heat is either absorbed or released during the
formation of a solution.
• The enthalpy change caused by the dissolution of
one mole substance.
• Ex. Na(OH) (s) -----> Na+(aq) + OH- (aq)
H(soln.) = -445.1kJ/mol
Chem II: 2.26.16
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy changes during
chemical and physical reactions.
Heat of Combustion
• Heat of reaction for the complete burning of one
mole of fuel.
CH4 (g) + 2O2 (g) -----> H2O(l) + CO2 (g)
H = -890kJ
Substance
Chemical Formula
Enthalpy Change
(kJ/mol)
Hydrogen
H2
-286
Carbon
C (s) graphite
-394
Methane
CH4 (g)
-890
Ethanol
C2H5OH
-1,368
Enthalpy: Changes in State
• Molar heat of fusion: H(fus)
Amount of heat absorbed by one mole of solid as it melts to
a liquid at constant temperature.
• Molar heat of solidification: H(solid)
Amount of heat released by one mole of liquid as it freezes
to a solid at constant temperature.
• Molar heat of vaporization: H(vap)
Amount of heat absorbed by one mole of liquid as it
vaporizes to a gas at constant temperature.
• Molar heat of condensation: H(cond)
Amount of released by one mole of gas as it condenses to a
liquid at constant temperature.
Chem II: 2.29.16
Objectives:
•I can distinguish between endothermic and
exothermic processes during changes with matter.
•I can calculate and analyze energy changes during
chemical and physical reactions.
Calculating Heats of Reaction (pg. 527)
1. Why would scientists need to calculate the heats
of reaction, H, when they can measure it by
performing the reaction in the lab?
2. What are two ways scientists can calculate heats
of reaction without performing the reaction in the
lab?
Calculating Heats of Reaction (pg. 527)
1. Why would scientists need to calculate the heats
of reaction, H, when they can measure it by
performing the reaction in the lab?
2. What are two ways scientists can calculate heats
of reaction without performing the reaction in the
lab?
Calculating Heats of Reaction (pg. 527)
1. Why would scientists need to calculate the heats
of reaction, H, when they can measure it by
performing the reaction in the lab?
• Reaction might occur too slowly to measure.
• Reaction might be an intermediate step is a multistep reaction.
• Might want to preserve reactants in a reaction.
• Reaction in lab might yield side products
(unwanted products) that affects the H.
Heat of Reaction Calculations
• Enthalpy difference between reactants and
products is independent of pathway.
• Enthalpy change can be calculated two ways:
* Hess’s Law: Sum of several thermochemical
equations.
*Standard Heat of Formation: The difference in heat
of formation of products and reactants in the
reaction.
H = Hf (products) - Hf (reactants)
Hess’s Law: Sum of Reactions
CH4(g) + 2O2 (g) ----> CO2 (g) + 2H2O(l)
H =?
C(s) + 2H2 (g) -----> CH4(g)
H = -74.80 kJ/mol
C(s) + O2 (g) -----> CO2 (g) H = -393.50 kJ/mol
H2 (g) + 1/2O2 (g)----> H2O (l) H= -285.83 kJ/mol
Enthalpy Change: Hess’s Law Applications
Standard Heat’s of Formation
CH4(g) + 2O2 (g) ----> 2CO2 (g) + 2H2O(l)
H =?
• Can calculate using standard heats of formation if
occurs at standard conditions.
H = Hf (products) - Hf (reactants)
• Standard Heats of Formation table (pg. 530)
CH4(g) H =
O2 (g) H =
CO2(g) H =
H2O(l) H =
Standard Heat’s of Formation
CH4(g) + 2O2 (g) ----> 2CO2 (g) + 2H2O(l)
H =?
• Can calculate using standard heats of formation if
occurs at standard conditions.
H = Hf (products) - Hf (reactants)
• Standard Heats of Formation table (pg. 530)
CH4(g) H =
O2 (g) H =
CO2(g) H =
H2O(l) H =
Chem II: 3.04.16
Objectives:
•I can calculate and analyze energy changes during
chemical and physical reactions.
Enthalpy Change: Hess’s Law Applications
Heat of Reaction Calculations
• Enthalpy change can be calculated two ways:
* Hess’s Law: Sum of several thermochemical
equations.
*Standard Heat of Formation: The difference in heat
of formation of products and reactants in the
reaction.
H = Hf (products) - Hf (reactants)
Standard Heat’s of Formation
CH4(g) + 2O2 (g) ----> 2CO2 (g) + 2H2O(l)
H =?
• Can calculate using standard heats of formation if
occurs at standard conditions.
H = Hf (products) - Hf (reactants)
• Standard Heats of Formation table (pg. 530)
CH4(g) H =
O2 (g) H =
CO2(g) H =
H2O(l) H =
Standard Heat’s of Formation
CH4(g) + 2O2 (g) ----> CO2 (g) + 2H2O(l)
H =?
• Can calculate using standard heats of formation if
occurs at standard conditions.
H = Hf (products) - Hf (reactants)
• Standard Heats of Formation table (pg. 530)
CH4(g) H =
O2 (g) H =
CO2(g) H =
H2O(l) H =
Enthalpy Change: Heat of Formation
Calculating Heats of Reaction
Thermochemistry Review Topics
• Qualitatively: Endothermic vs. Exothermic
• Q=mc T equation and calorimetry
applications.
• Law of Thermodynamics
• Enthalpy Change:( H): calculated using
thermochemical equation, Hess’s Law, and
Heat of formation.
Chem II: 3.24.15
Objectives:
• Thermochemistry Exam
Thermochemistry Review
•Radiation evenly distributed throughout the universe.
•Temp: -270 oC (few degrees above absolute zero)
•Minute fluctuations in temperature observed.
bbc.co.uk
dailygalaxy.com
Normal Matter: Influenced by gravity and does emit or
reflect light.
Dark Matter: Influenced by gravity, but does not emit or
reflect light.
Dark Energy: Seems to oppose gravity. Currently most
mysterious to scientists.
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Calorimetry Food Lab
Purpose:
Metallic Bonding
Intermolecular Forces
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Free Energy