Synthesis of Potassium Dioxalatocuprate

Dihydrate Lab 5

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.

DefinitionsO Stoichiometry is the study of mass

relationships in a chemical reaction.

O The law of definite proportions states that compounds or elements react chemically to form a new compound in definite proportions.

O Before any attempt at calculations are made, reactions have to be balanced first. Only then can we obey the law of definite proportions.

O The limiting reagent is the reactant that runs out first in a chemical reaction.

ReactionO Add two water soluble compounds

together to form an insoluble solid that precipitates out.

O Filter out all excess water soluble reagent.

O Isolate the precipitate on filter paper utilizing three rinse compounds (water, ethanol, acetone) and vacuum filtration.

O Determine the percent yield recovered.

Equipment Setup

Equipment Setup

Reaction Reagents Products

1CuSO45H2O (aq)+ 2K2C2O4H2O(aq) 1K2[Cu(C2O4)2]2H2O(s)+

5H2O + 1K2SO4(aq)

copper potassium potassiumpotassium

sulfate oxalate dioxalatocuprate sulfatepentahydrate monohydrate dihydrate

Materials and Precautions

O Balance function O Weighing paperO Scoopula and contaminationO Cleanup

O Hotplate functionO Don’t burn yourself!

O Ice bath preparation O Use more ice than water.

O Location of the filter paper, chilled distilled water, ethanol, and acetone

WasteO Excess or spilled potassium oxalate monohydrate

should be disposed in the oxalate solid waste container in the fume hood.

O Excess or spilled copper sulfate pentahydrate should be disposed in the copper solid waste container in the fume hood.

O Filtrate should be disposed in the filtrate waste container in the fume hood.

O Dry product should be disposed in the copper solid waste container in the fume hood.

O After all product is scraped off, filter paper should be placed in the filter paper waste container in the fume hood.

Safety ConcernsO Reagents:

O AcetoneO Copper Sulfate PentahydrateO Denatured AlcoholO Potassium Oxalate Monohydrate (Teratogen)

O Eye Contact:O Stinging, tearing, redness, pain, irritation, tissue burns, conjunctivitis,

ulceration, clouding of cornea, and blurred visionO Skin Contact:

O Defatting, dehydration, irritation, redness, pain, drying, flaking, cracking, itching, and severe burns

O Inhalation:O 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.

O Ingestion:O Abdominal pain, nausea, vomiting, headaches, gastritis, gastrointestitis,

intoxication, blindness, and death. Aspiration into the lungs can cause severe lung damage.

Lab 6 ReminderO If you have not started on the pre-labs for Lab 6

yet, start as soon as possible.O Read the lab write-up in your manual (pp 149 -

174).O Complete the pre-lab questions (pp. 149 - 174)

in MicroLab™ in the SCICom lab (NSB 204), Chemistry Resource Center (CPSB 302K) or on your personal computer if you download the program. The program may be downloaded from http://www.microlabinfo.com under the Downloads link.

O Take this exercise seriously. You will be required to complete a similar exercise in lab next week without help from your lab manual.

Skill EvaluationsO Review the graduated glassware,

safety, and calibration question sections.

O Remember your goggles, lab manual, and Lab 5 Report.

O Study for the next quiz.