University of Washington Chem 162 lab 4- All Answers are Correct (Graded A)
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Course
CHEM 162 General Chemistry
Institution
University Of Washington
Chem 162 - Experiment #4
I. Fractional Crystallization of KNO3 with (NH4
)2Fe(SO4
)2
·6H2O Impurity
II. The Solubility Curve of KNO3
DATA, CALCULATIONS, AND GRAPHS
By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, and
...
university of washington chem 162 lab 4 all answers are correct graded a
chem 162 experiment 4 i fractional crystallization of kno3 with nh4 2feso4 2 ·6h2o impurit
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CHEM 162 General Chemistry
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Name: Jordan Martel Quiz Section: CH Assigned
ID Number: 1666548 Lab Partner: Emerson Points
Chem 162 - Experiment #4
I. Fractional Crystallization of KNO3 with (NH4)2Fe(SO4)2·6H2O Impurity
II. The Solubility Curve of KNO3
Grading: 60 pts (10 pts notebook, 50 pts template) Note: 10
All sections of
By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, an d
that all calculations and responses other than the reporting of raw data are your own independent work. Failure to sign
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be typed.
DATA, CALCULATIONS, AND GRAPHS
Part I: Fractional Crystallization of KNO3 with (NH4)2Fe(SO4)2.6H2O Impurity
A. Starting Components (Fract. Crystallization #0) data entry 3
Step 3: Mixture before first crystallization 3
mass KNO3 4.470 g
mass (NH4)2Fe(SO4)2.6H2O 0.588 g
Total mass of the sample mixture 5.058 g
% Impurity (i.e., % Fe compound in the mixture)* 11.63 %
*(This is your % impurity for Fract. Crystallization # 0)
Fract. Crystallization #1
Step 7: mass of dry filter paper + watch glass 63.126 g
Step 10: mass of KNO3 crystals + filter paper + watch glass 66.717 g
mass of KNO3 crystallized 3.591 g
% KNO3 recovered (% of KNO3 in Step A.3.) 80.300 % 1
Step 11: mass of KNO3 crystals to be analyzed for purity in Part I.C 0.102 g
B. Fract. Crystallization # 2 (Re-crystallization)
Step 5: mass of dry filter paper + watch glass 63.128 g
Step 7: mass of KNO3 crystals + filter paper + watch glass 65.056 g
mass of KNO3 crystallized 1.928 g
% KNO3 recovered (% of KNO3 in Step A.3.) 43.100 % 1
Step 8: mass of KNO3 crystals to be analyzed for purity in Part I.C 0.405 g
1
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, C. Analysis to Determine % Impurity
First Crystallization
Step 3: Absorbance of the Fe(phen)32+ complex at 510 nm 1.79
Does the absorbance exceed the desired range (0 to 2.0 A)? _____no_______
If so, what dilution factor did you use in order to get the absorbance in the desired range? _____N/A________
2
What is your absorbance after dilution? (if applicable) N/A
Multiply your absorbance by the dilution factor (if applicable) N/A
Molar Absorptivity of ferroin, e
-1 -1
1.25E+04 M cm
Calculate the molarity of Fe2+ from the absorbance (pathlength = 1 cm) 0.000143 M
Type your calculation for molarity of Fe2+ (1 mol ferroin = 1 mol Fe 2+)
2
Molarity of Fe2+=(absorbance of Fe(phen)3 2+)/(molar absorbity of ferroin)*1cm
1.79/(1.25E+04 M^-1*cm^-1)*1cm)
=1.43E-04M
Volume of ferroin complex solution prepared in Steps C.1. and C.2. 0.0100 L
Calculate the moles of Fe2+ (moles of Fe2+= moles of (NH4)2Fe(SO4)2·6H2O) 1.43E-06 moles
Type your calculation for moles of Fe2+
moles Fe2+=(molarity of Fe2+)(volume of ferroin complex solution)
(1.43E-04M)(0.0100L) 2
=1.432E-06
Calculate the molar mass (NH4)2Fe(SO4)2·6H2O 392.15 g/mole
Calculate grams of (NH4)2Fe(SO4)2·6H2O in the crystals 0.0005616 g
Type your calculation for grams of (NH4)2Fe(SO4)2·6H2O
(NH4)2Fe(SO4)2*6H2O = (moles of Fe2+)(molar mass (NH4)2Fe(SO4)2*6H2O)
=(1.432E-06 moles)(392.15g/mole) 2
=5.616E-04
Mass KNO3 crystals analyzed for purity (from Step A.11.) (this cell will autofill from cell F41) 0.102 g
Calculate % mass of (NH4)2Fe(SO4)2·6H2O in the crystals 0.55 %
(This is your % impurity for Fract. Crystallization # 1)
Type your calculation for % mass of (NH4)2Fe(SO4)2·6H2O in the crystals.
(5.616E-04g/0.102g)*100 2
=0.55%
2
This study source was downloaded by 100000845522993 from CourseHero.com on 05-24-2022 19:49:51 GMT -05:00
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