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Monday and Tuesday April 16 and 17

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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 cal

1 cal = 4.184 J

Temperature

Measure of random motion of a substance

Measured in ̊C, ̊F, or K

- Convert temperature
- Change in temperature
- Convert to grams of a substance
- Q=SM∆T

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

∆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 6.00 mol of H2O to grams.

108. g H20

Q = Energy (heat) required in Joules

S = specific heat capacity in J/g̊C

M = mass of the sample in grams

∆T = change in temperature in ̊C

Specific Heat Capacity

The amount of energy required to raise the temperature of one gram of a substance by one degree Celsius.

How can people walk on hot coals?

http://www.youtube.com/watch?v=3ToRsSYSkbY

Specific Heat Capacity

The amount of energy required to raise the temperature of one gram of a substance by one degree Celsius.

How much energy is needed to warm 7.40 g of water from 17.0 ̊C to 35.0 ̊C?

Q = want

S = 4.184 J/g̊C (from table)

M = 7.40 g

∆T = 35.0 ̊C – 17.0 ̊C= 18.0 ̊C

Homework:

Thermo WS 1

10.2 (pg 291 – 292)

10.5 (pg 294 – 300)

Practice Problems

Pg 318 - 320 # 6-10, 22-28, 49-58

Rewrites are due Friday, 4/20

Extra credit assignment due 5/11

How much energy is needed to warm 3.60 g of lead from 17.0 ̊C to 35.0 ̊C?

Q = want

S = 0.128 J/g̊C (from table)

M = 3.60 g

∆T = 35.0 ̊C – 17.0 ̊C= 18.0 ̊C

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 = want

S = 2.03 J/g̊C (from table)

M = 1.0 x 103 g

∆T = 110.0 ̊C – -20.0 ̊C= 130.0 ̊C

Calorimeter 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.

Stirrer

Thermometer

Water

Metal pieces

Insulated container

A 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?

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

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

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

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

Homework:

Thermo WS 2

Reminders:

Rewrites are due FRIDAY, 4/20

Extra credit due 5/11

If you rewrote your Lab 3.21 for proficiency, turn in the highlighted rewrite and the original paper to the turn in bin.

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?

Clear desk except a pencil and calculator

Purpose: Determine the specific heat capacity of an unknown metal and identify the metal.

Complete the prelab

assignment

BEFORE class.

Dress appropriately

for lab

- Don’t poke the thermometer through the cups
- Put metal in water and cover as quickly as possible

Homework:

Thermo WS 3

Thermo prelab

Reminders:

Rewrites are due FRIDAY, 4/20

No exceptions

In 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?

- Don’t poke the thermometer through the cups
- Put metal in water and cover as quickly as possible

◦Work on write up

Title, 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

Homework:

Thermo Lab Write Up

GeneralReminders:

Extra Credit due 5/11

Thermodynamics Test 4/25 and 4/26