Transcript Gravimetric Analysis for Phosphorus

Due Today:
1 . Gravimetric
Analysis of
Phosphorus PreLab
GRAVIMETRIC ANALYSIS
FOR PHOSPHORUS
2. Redox Titration
Short Report
Homework:
1. Gravimetric
Analysis of
Phosphorus
Formal Lab
Report
2. Acid-Base
Titration Pre-Lab
OBJECTIVE
Determine the phosphorus content of
commercial fertilizer
Compare to reported value
KEY TERMS
Quality Control Experiment – verify label
Phosphorus
Gravimetric Analysis – set of analytical
methods to quantitatively determine an
analyte based on the mass of a solid
Dissolve
Precipitate
Filter
PROCEDURE NOTES
Skip Step 4
Step 14&15 – masses should be within
0.010g
Collect Data from 2 additional groups
WASTE
Filtrate → sink
Filter Paper → trashcan
Acetone Filtrate → acetone waste container
Product → waste container in hood
RISK ASSESSMENT
Ammonium
Hydroxide
 Danger
 Corrosive
 Inhalation Hazard
RISK ASSESSMENT
Acetone
 Danger
 Flammable
 Skin Irritant
CALCULATIONS
■ Mass % of P in MgNH4PO4:
Mass % of P 
molecular
molecular
mass P
mass MgNH
 100
4
PO
4
■ Mass of P in Precipitate:
Mass of P  mass%  mass
precipitat e
CALCULATIONS
Use stoichiometry to convert from grams of
P to grams of P 2 O 5
■ Mass % P2O5 :
mass % P 2 O 5 
mass P 2 O 5
mass sample
 100
CALCULATIONS
■ Percent Difference :
% Difference

package - experiment
package
al
 100