Synthesis of Potassium Dioxalatocuprate Dihydrate Lab 7

Purpose This lab will help further your understanding of stoichiometric relationships between reactants and products of chemical reactions. This includes an understanding of concepts such as limiting reagents, yields, and percent error.

Definitions Stoichiometry is the study of mass relationships in a chemical reaction. The law of definite proportions states that compounds or elements react chemically to form a new compound in definite proportions. Before any attempt at calculations are made, reactions have to be balanced first. Only then can we obey the law of definite proportions. The limiting reagent is the reagent that runs out first in a chemical reaction.

Reaction Add two water soluble compounds together to form an insoluble solid that precipitates out. Filter out all excess water soluble reagent. Isolate the precipitate on filter paper utilizing three rinse compounds (water, ethanol, acetone) and vacuum filtration. Determine the percent yield recovered.

Equipment Setup

Filtering flask

Reaction Reagents Products A B C 1CuSO 4  5H 2 O (aq) +2K 2 C 2 O 4  H 2 O (aq) 1K 2 [Cu(C 2 O 4 ) 2 ]  2H 2 O (s) + D E 5H 2 O + 1K 2 SO 4(aq) copper potassium oxalate potassium potassium sulfate monohydrate dioxalatocuprate sulfate pentahydrate dihydrate

Calculations Moles of A = Moles of B = Limiting Reagent (LR) Ratio = Moles of C LR = (moles of LR) x Theoretical Yield = (moles of C) x (fw of C) % Yield = x 100%

Materials and Precautions Balance function  Weighing paper  Scoopula and contamination  Cleanup Hotplate function  Don’t burn yourself! Ice bath preparation  Use more ice than water. Location of the filter paper, chilled distilled water, ethanol, and acetone

Waste Excess or spilled potassium oxalate monohydrate should be disposed in the oxalate solid waste container in the fume hood. Excess or spilled copper sulfate pentahydrate should be disposed in the copper solid waste container in the fume hood. Filtrate should be disposed in the filtrate waste container in the fume hood. Dry product should be disposed in the copper solid waste container in the fume hood. After all product is scraped off, filter paper should be placed in the filter paper waste container in the fume hood.

Safety Concerns Reagents:  Acetone  Copper Sulfate Pentahydrate  Denatured Alcohol  Potassium Oxalate Monohydrate (Teratogen) Eye Contact:  Stinging, tearing, redness, pain, irritation, tissue burns, conjunctivitis, ulceration, clouding of cornea, and blurred vision Skin Contact:  Defatting, dehydration, irritation, redness, pain, drying, flaking, cracking, itching, and severe burns Inhalation:  Irritation, ulceration, and perforation of the respiratory tract, coughing, sore throat, shortness of breath, dizziness, dullness, drowsiness, loss of appetite, inability to concentrate, headache, nervousness, cramps, CNS depression, narcosis, and unconsciousness. Fumes from heating may cause symptoms similar to a cold. Ingestion:  Abdominal pain, nausea, vomiting, headaches, gastritis, gastrointestitis, intoxication, blindness, and death. Aspiration into the lungs can cause severe lung damage.

Next Week: Lab 8 Reminder Read the required reading material from your textbook and lab manual. Complete your pre-lab questions. Submit your Lab 7 Report.