Chemistry Week

35

Please take a seat and get ready for lab day!

May 13, 2012

AGENDA:1 – Bell Ringer &

Agenda2 – Lab Introduction3 – Wash Hands4 – M&Mium Decay Lab5 – Post Lab Questions6 – Turn in Lab7 – Summary

Today’s Goal:Students will be able to

model radioactive decay through a lab investigation.

HomeworkNONE!

If you missed Friday’s Unit 7 Exam, you must come TODAY AFTER SCHOOL IN ROOM 301 to take it (Please be there by 3:30)!!

Monday, May13th

Objective: Students will be able to model radioactive

decay through a lab investigation.

Bell Ringer: In your own words, explain what the

word radiation means?

30 seconds Remaining…

Monday, May13th

Objective: Students will be able to model radioactive

decay through a lab investigation.

Bell Ringer: In your own words, explain what the

word radiation means?

May 13, 2012

AGENDA:1 – Bell Ringer &

Agenda2 – Lab Introduction3 – Wash Hands4 – M&Mium Decay Lab5 – Post Lab Questions6 – Turn in Lab7 – Summary

Today’s Goal:Students will be able to

model radioactive decay through a lab investigation.

HomeworkNONE!

If you missed Friday’s Unit 7 Exam, you must come TODAY AFTER SCHOOL IN ROOM 301 to take it (Please be there by 3:30)!!

Monday, May13th

SUMMARY:Scientists use the half-life of the

radioactive isotope Carbon-14 to determine the age of fossils or artifacts from archeology sites. Based upon today’s lab, how do you think this process works?

Procedure1. Wash Hands FIRST. I have soap, paper towels and hand

sanitizer.

2. Count the number of M&Miums you have initially.

3. Place all into the cup, shake 2 or 3 times, then dump out onto paper.

4. Remove all M&Miums with the “m” side down, and put them aside. These atoms have decayed.

5. Count how many M&Mium have the “m” side up. These are the atoms that have not decayed. Put these atoms back into the cup. This represents 1 half-life.

6. Complete the steps above for half-lifes 2-5. Record all data.

7. Bring your group’s data up to me so I can compile the class data.

M&Mium Decay Data

Half -- Life Group Data Class Data

0

1

2

3

4

5

1st Period Lab Groups

AmyRobertArielleMariama

Quay HydeiaShanaPatricia

SaraIsaiahNiamarionCarla

GeraldTumaniChronicleAshanti

ZahraJaneImaniChibuzo

RahamanhJasmineDanielleKaylaKaylan

JudyMariaTaylorJoy

1

23

45

6

7RahamanhTatianaChoiceJustin

8

2nd Period Lab Groups

ChrisAginahJennaJared

ReganOmariAhziaKeira

KeanthoyJoeAjaiNathaly

Camille AlanJavonteJasmine

DaijaSergioRyanTesia

OtisMayaNajaeErick

AngeliqueKaylaLaurynJaniece

1

23

45

6

7

5th Period Lab Groups

TyreseCourtneyRomalleTiara

NeTanyahTajanaDarnellDestini

HunterClarissaKailahJelaniDreshion

Michael KJudahJamilleKahlia

ErikSavonKhamyaVictoria

TanishaJocelynKhyriBadieye

Michael GMurrellChanticeBreanna

1

2

3 45

6

7

6th Period Lab Groups

JamieTenishaAlexJouet

JulianAryaCyntrallNicole

JessicaJordinMichael

KhalinD’angeloErica

KylaBriaTeonNanyamka

SydneyCaylenD’niko

KihindeArielTyler

1

2

3

4

5

6

7

8th Period Lab Groups

KeonCharlesAbdulPatience

AngelaEbonyBrianna SEric

PaulKenneshaNakiaSam

TayvaTamarhaCarlEriun

TianaRavionBreanna R

JalaunMayaSydneyWillie

Alexis CourtneyBrittany DavidElijah

1

2

3 45

6

7

Cornell Notes

Topic: Heat Curves and Heat Capacity

Date: 4/2/2013 Measuring energy:

Universe = Surroundings + System

SurroundingsSurroundings

SystemHeat Heat

Endothermic Exothermic

Review from

yesterday

q =(+)

q =(-)

Cornell Notes

Use this equation to calculate the heat released (q = neg.) or absorbed (q = pos.) when temperature is changing.

q = m · Cp · ∆T

Use this equation if you are calculating the heat released (q = neg.) or absorbed (q = pos.) when substance is melting or freezing.

q = HF · m

Use this equation if you are calculating the heat released (q = neg.) or absorbed (q = pos.) when substance is boiling (evaporating) or condensing.

q = HV · m

When to use heat

of fusion:

When to use heat of vaporizatio

n:

When to use heat capacity:

More Practice Problems (Show work on loose leaf paper)1. What is the amount of energy need to vaporize 3500 g of water?

2. Calculate the amount of energy needed to melt 10 grams of mercury.

3. What is the amount of energy needed to vaporize 360 grams of butane.

4. What is the amount of energy released when 15 g of ether freezes.

Substance

Hf (J/g)

Hv (J/g)

Butane 86 414

Ether 95 392

Water 334 2260

Mercury 115 290

5. Challenge: How many joules of energy are absorbed when 25g of steam cools from 100oC to produce water at 10oC? (2-step)

Cornell Notes Topic: Review Heat Calculations Date: 4/4/2013Heat Capacity = the amount of heat required to change the temperature of an object (based on the specific heat).

q = m · Cp · ∆T Units = J = g · (J/g°C) · °C

Molar Heat of Fusion (HF): the heat absorbed by one mole of a solid substance as it melts to a liquid at constant temperature.

q = HF · m Units: J = (J/g) · g

Molar Heat of Vaporization (HV): the heat necessary to vaporize (turn into a gas) one mole of a given liquid at constant temperature.

q = HV · m Units: J = (J/g) · g

What is the heat

of fusion?

What is the heat of

vaporization?

What is heat

capacity?

Cornell Notes

How much heat does 10 g of water absorb if it is heated from 10°C to 25°C? q = m · Cp · ∆T

q = (10 g) ·(4.184 J/g°C)·(25 °C - 10°C) = 627.6 J

How much heat is released when 10 grams of water melts? q = HF · m

q = (334 J/g)·(10g) = - 3340 J

How much heat is absorbed if 5 grams of water evaporates (boils)? q = HV · m

q = (2260 J/g)·(60g) = 11,300 J

Calculatingusing heat of fusion:

Calculating using heat

of vaporizatio

n:

Calculating using

heat capacity:

-40

-20

0

20

40

60

80

100

120

140

Heat Curve of Water

Time

Tem

pera

ture

(C

)

Cornell Notes

Diagram Heat

Curves.

Solid

Liquid

Vapor/Gas

Endothermic =

system

Melting

Boiling

To calculate heat, temperature is

changing so you would use q = m·CP·∆T

To calculate heat, temperature is not

changing so you would use q = HV·m

-40

-20

0

20

40

60

80

100

120

140

Heat Curve of Water

Time

Tem

pera

ture

(°C

)

Cornell Notes

Diagram Heat

Curves.

Solid

Liquid

Vapor/Gas

Exothermic =

system

Freezing

Condensing

To calculate heat, temperature is

changing so you would use q = m·CP·∆T

To calculate heat, temperature is not

changing so you would use q = HF·m

*Remember the sign of q will be

opposite!