monday and tuesday april 16 and 17
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Monday and Tuesday April 16 and 17. Chapter 10: Thermodynamics. What is energy? Is there a difference between heat and temperature?. Heat Energy flow caused by a temperature difference Measured in J or cal 1 cal = 4.184 J. Temperature Measure of random motion of a substance - PowerPoint PPT PresentationTRANSCRIPT
Monday and TuesdayApril 16 and 17
Chapter 10:Thermodynamics
What is energy?
Is there a difference between heat and temperature?
Heat
• Energy flow caused by a temperature difference
• Measured in J or cal1 cal = 4.184 J
Temperature
• Measure of random motion of a substance
• Measured in ̊C, ̊F, or K
Calculations Convert temperature Change in temperature Convert to grams of a substance Q=SM∆T
Converting T ( ̊F to ̊C)Fahrenheit to Celsius
T ( ̊C) = ( T(°F) – 32) x (5/9)
Ex: Convert 65 ̊F to ̊C T ( ̊C) = ( T(°F) – 32) x (5/9) T ( ̊C) = ( 65 °F – 32) x (5/9) T ( ̊C) = 18. ̊C
Change in T (∆T)∆T = T final – T initial
Ex: If a cup of boiling water is left on the counter until it comes to room temperature (20 ̊C), what is the change in temperature?∆T = T final – T initial ∆T = 20 ̊C – 100 ̊C ∆T = -80 ̊C
Convert to grams (from mol)
Convert 6.00 mol of H2O to grams.
6.00 mol H2O18.02 g
H2O =
1 mol H2O
108. g H20
Q = SM∆TQ = Energy (heat) required in JoulesS = specific heat capacity in J/g ̊CM = mass of the sample in grams∆T = change in temperature in ̊C
Substance Specific Heat Capacity (J/g̊C)air 1.00
carbon (graphite) 0.711carbon dioxide 0.832
granite 0.803iron 0.448lead 0.128
mercury 0.14water (liquid) 4.184
ice 2.03steam 1.99
Specific Heat CapacityThe amount of energy required to raise the temperature of one gram of a substance by one degree Celsius.
Heat transferHow can people walk on hot coals?
http://www.youtube.com/watch?v=3ToRsSYSkbY
Substance Specific Heat Capacity (J/g̊C)air 1.00
carbon (graphite) 0.711carbon dioxide 0.832
granite 0.803iron 0.448lead 0.128
mercury 0.14water (liquid) 4.184
ice 2.03steam 1.99
Specific Heat CapacityThe amount of energy required to raise the temperature of one gram of a substance by one degree Celsius.
Q = SM∆THow much energy is needed to warm 7.40 g
of water from 17.0 ̊C to 35.0 ̊C?Q = wantS = 4.184 J/g ̊C (from table)M = 7.40 g∆T = 35.0 ̊C – 17.0 ̊C= 18.0 ̊C
Recommended Reading
10.2 (pg 291 – 292)10.5 (pg 294 – 300)
Practice Problems
Pg 318 - 320 # 6-10, 22-28, 49-58
Homework: Thermo WS 1
Rewrites are due Friday, 4/20Extra credit assignment due 5/11
Wednesday and ThursdayApril 18 and 19
Warm UPHow much energy is needed to warm 3.60 g
of lead from 17.0 ̊C to 35.0 ̊C?Q = wantS = 0.128 J/g ̊C (from table)M = 3.60 g∆T = 35.0 ̊C – 17.0 ̊C= 18.0 ̊C
Review Homework
Review Homework
Practice Problem
How much energy is introduced in to 1.0 kg of ice at -20.0°C, to turn it into steam at 110.0°C?
Q = wantS = 2.03 J/g ̊C (from table)M = 1.0 x 103 g∆T = 110.0 ̊C – -20.0 ̊C= 130.0 ̊C
CalorimeterCalorimeter is a heat measuring device.
The calorimeter is generally used to measure the amount of heat energy transferred during a reaction.
Using this information, one can calculate the specific heat of a substance or other heat related information.
Insulated container
Stirrer
Water
Metal pieces
Thermometer
CalorimeterA closed system in which energy is
maintained.
-(Q 1) = Q 2
If a 30.0 g block of iron is put into the calorimeter and -9.87 J of energy is released, how much energy does the water take on?
Calorimeter
A sample of aluminum (0.895 J/g °C )at 75.0°C was placed in a calorimeter containing 25.0 grams of water at 20.0°C. The temperature stopped changing at 29.4°C. What is the mass of the sample?
-(Q 1) = Q 2-(SmetalMmetal∆Tmetal )= SwaterMwater∆Twater
Practice Problems
A 4.57 g sample of metal is heated to 57.8 ̊C and placed in 150. mL of water that is at 20.0 ̊C. The temperature of the water increases to 40.0 ̊C. What is the specific heat capacity of the metal?
-(Q 1) = Q 2-(SmetalMmetal∆Tmetal )= SwaterMwater∆Twater
Practice Problems
A 8.13 g sample of iron is heated to 45.4 ̊C and placed in 400. mL of water that is at 23.0 ̊C. What will the final temperature?
-(Q 1) = Q 2-(SmetalMmetal∆Tmetal )= SwaterMwater∆Twater
Practice Problems
A 7.01 kg sample of iron is heated to 69.4 ̊C and placed in 6.71 L of water. The final temperature of the water is 39.8 ̊C. What is the initial temperature of the water?
-(Q 1) = Q 2-(SmetalMmetal∆Tmetal )= SwaterMwater∆Twater
Practice Problems
Homework and Reminders
Homework:Thermo WS 2
Reminders:Rewrites are due FRIDAY, 4/20Extra credit due 5/11
FridayApril 20
If you rewrote your Lab 3.21 for proficiency, turn in the highlighted rewrite and the original paper to the turn in bin.
REWRITES DUE
Warm Up
If 150.0 grams of iron at 95.0 °C, is placed in an insulated container containing 500.0 mL of water at 25.0 °C, and both are allowed to come to the same temperature, what will that final temperature be?
Review Homework
Review Homework
Quiz Time
Clear desk except a pencil and calculator
Thermodynamics Lab
Purpose: Determine the specific heat capacity of an unknown metal and identify the metal.
Complete the prelabassignment BEFORE class.
Dress appropriatelyfor lab
Notes for the lab• Don’t poke the
thermometer through the cups
• Put metal in water and cover as quickly as possible
Homework and Reminders
Homework:Thermo WS 3Thermo prelab
Reminders:Rewrites are due FRIDAY, 4/20
No exceptions
Monday and TuesdayApril 23 and 24
Warm UpIn a calorimeter 187 mL of 18.9 ̊C water is mixed with a 4.32 g block of 92.0 ̊F granite. What will the final temperature be?
Review Homework
Review Homework
Lab Time• Don’t poke the
thermometer through the cups
• Put metal in water and cover as quickly as possible
Done in lab?
◦Work on write upTitle, purpose, data tables, calculations, analysis
If you finish the lab turn it in to the turn in bin, if not it is your homework
◦Work on practice test if you finish the lab
Reminders
Homework:Thermo Lab Write Up
General Reminders:Extra Credit due 5/11Thermodynamics Test 4/25 and 4/26