Name: Quiz Section: CH Assigned
ID Number: Lab Partner: 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 this report,
this declaration will result in 5 points being deducted from your report score. except the
structural
Signature: formulas, must
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 entry3
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
, 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, 1.25E+04 M -1 -1
cm
Calculate the molarity of Fe2+ from the absorbance (pathlength = 1 cm) 0.000143 M
2+ 2+
Type your calculation for molarity of Fe (1 mol ferroin = 1 mol Fe )
Molarity of Fe2+=(absorbance of Fe(phen)3 2+)/(molar absorbity of ferroin)*1cm 2
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. Calculate 0.0100 L
the moles of Fe2+ (moles of Fe2+= moles of (NH4)2Fe(SO4)2·6H2O) 1.43E-06 moles
2+
Type your calculation for moles of Fe
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
ID Number: Lab Partner: 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 this report,
this declaration will result in 5 points being deducted from your report score. except the
structural
Signature: formulas, must
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 entry3
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
, 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, 1.25E+04 M -1 -1
cm
Calculate the molarity of Fe2+ from the absorbance (pathlength = 1 cm) 0.000143 M
2+ 2+
Type your calculation for molarity of Fe (1 mol ferroin = 1 mol Fe )
Molarity of Fe2+=(absorbance of Fe(phen)3 2+)/(molar absorbity of ferroin)*1cm 2
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. Calculate 0.0100 L
the moles of Fe2+ (moles of Fe2+= moles of (NH4)2Fe(SO4)2·6H2O) 1.43E-06 moles
2+
Type your calculation for moles of Fe
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
