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