chemistry week 26

Chemistry Week

26

Please get out your calculator!

March 12, 2013

AGENDA:1 – Agenda/ Bell Ringer 2 – Pre-Lab Instructions3 – Lab4 – Clean-up and Post-

Lab

Today’s Goal:Students will be able to

determine a limiting reactant and calculate a percent yield for a laboratory experiment.

Homework1. Limiting Reactant Lab

– Calculations due tomorrow

2. Stoichiometry and Limiting Reactant

3. If you missed Friday’s Quiz you must come make it up by Friday.

Tuesday, March 12th

Objective: Students will be able to determine a

limiting reactant and calculate a percent yield for a laboratory experiment.

Bell Ringer:Predict the products of the following

chemical equation and balance (see Pre-lab):

___HCl + ___Zn ______ + ______

(*hint: Zn is a +2 charge)

30 seconds Remaining…

Tuesday, March 12th





___HCl + ___Zn ______ + ______


March 12, 2013

AGENDA:1 – Agenda/ Bell Ringer 2 – Pre-Lab Instructions3 – Lab4 – Clean-up and Post-

Lab

Today’s Goal:Students will be able to

determine a limiting reactant and calculate a percent yield for a laboratory experiment.

Homework1. Limiting Reactant Lab

– Calculations due tomorrow

2. Stoichiometry and Limiting Reactant

3. If you missed Friday’s Quiz you must come make it up by Friday.

Tuesday, March 12th





___HCl + ___Zn ___ ZnCl2+ ___ H2


Lab Notes

We completed the Pre-Lab as the Bell Ringer. Please make sure you complete it while you are doing your lab.

You need to work quickly! Let each reaction occur for at least 7 minutes, or until all bubbles stop forming.

Make sure once you are done with a reaction, you quickly set up your next reaction. You want to leave as much time as possible for the reaction.

While you are waiting for the reaction to proceed, you can be setting up for your next trial by measuring out the HCl and Zn and doing the calculations.

1st Period Lab Groups

AmyRobertArielleMariamaTatiana

Quay HydeiaShanaPatricia

SaraIsaiahNiamarionCarla

GeraldTumaniChronicleAshantiChoice

ZahraJaneImaniChibuzo

RahamanhJasmineDanielleKaylaKaylan

JudyMariaTaylorJustinJoy

1

23

45

6

7

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


JamieTenishaAlex

JulianAryaCyntrallNicole

JessicaJordinMichael

KhalinD’angeloErica

KylaBriaTeonNanyamka

SydneyCaylenD’niko

KihindeArielTyler

1

2

3

4

5

6

7


KeonCharlesAbdulPatience

AngelaEbonyBrianna SEric

PaulKenneshaNakiaSam

TayvaTamarhaCarlEriun

TianaRavionBreanna R

JalaunMayaSydneyWillie

Alexis CourtneyBrittany DavidElijah

1

2

3 45

6

7

Monday, March 11th


limiting reactant and calculate a percent yield.

Bell Ringer: 2 C4H10 + 13 O2 8 CO2

+ 10 H2O

How many grams of H2O are formed from 5.5 g of O2?

5.5g O2 x 1mol O2 x 10molH2O x 18 g H2O =

32 g O2 13 mol O2 1mol H2O

2.4 g H2O= 5.5 x 1 x 10 x 18 g H2O =32 x 13 x 1

Obj: SWBAT determine a limiting reactant and calculate a percent yield.

Date: 3/11/2013What is

a Limitin

gReacta

nt?

• In a chemical reaction, the amount of product that can be produced is limited by the reactant that can produce the least amount of products based upon the ratios in which they react.

• The reactant that produces the least amount of product is called the limiting reactant.

Example

How many bikes can be made if you have:• 18 wheels• 10 handlebars• 12 seats• 10 frames

• You can make 9 bikes• Wheels are the

limiting reactant.

Example #1

All limiting reactant problems start with a balanced chemical equation.

4 FeCl3 + 3 O2 2 Fe2O3 + 6 Cl2

How many moles of Cl2 can be produced if 5 moles of FeCl3 react with 4 moles of O2?5 mol FeCl3 x

6 mols Cl2 =

4 mols FeCl3

7.5 mol Cl2

4 mol O2 x 6 mols Cl2 =

3 moles O2

8 mol Cl2

• FeCl3 is the limiting reactant because 7.5 moles of Cl2 were produced.

• O2 was the excess reactant.

Example #2

2 C2H6 + 7 O2 4 CO2 + 6 H2O

How many grams of H2O can be produced if 15 grams of C2H6 react with 45 grams of O2?

Molar masses: C2H6 = 30 g/mol; O2 = 32 g/mol; H2O = 18g/mol15 g C2H6

x

1mol C2H6 x30 g C2H6

6 mol H2O x

2 mol C2H645 g O2 x 1 mol O2 x

32 g O2

21.7 g H2O

• O2 is the limiting reactant• C2H6 is the excess reactant

18 gH2O =1 mol H2O

27 g H2O

6 mols H2O x

7moles O2

18 g H2O =

1 mol H2O

What is Percent Yield?

• The ratio of the actual yield (what you actually produced) to the theoretical yield (what you calculated) for a chemical reaction expressed as a percentage.

• It’s a measure of the efficiency of the reaction. (think of it like a grade for the reaction)Exampl

e

Percent Yield = Actual Value x 100 Theoretical ValueWhat would be the percent yield of the previous reaction if only 20 g of H2O were produced?Percent Yield = 20 g H2O x 100 = 21.7 g H2O

92.2 %

Obj: SWBAT determine a limiting reactant and calculate a percent yield.

Date: 3/11/2013

Set-Up Help

Balanced Chem Eq: aA bB1. Calculate the molar masses of both

compounds in the problem2. Convert: remember Given and WantGiven(g) x1 mol Given x mol Want x Mol.mass Want =

Mol.mass Given mol Given 1 mol Want3. Multiply everything in numerator. 4. Multiply everything in the denominator5. Divide Numerator by Denominator.

`

Set-Up Help

Balanced Chem Eq: aA bB Mole A Mole B Gram B:Mole A x b Mole B x Molar Mass B = Gram B

a Mole A 1 mol B

Gram A Mole A Mole BGram A x 1Mole A x b Mole B = Mole B

Molar Mass A a mol A

chemistry week 26

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