Experiment 4 Lab Report PDF

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Michael Arnold Ting Wang Lab Partner: Jacob Porter CHE 111-048 October 16, 2016 Experiment 4 Discovering Limestone Composition by Gravimetric Analysis Introduction: Limestone is a mineral composed of several different elements and compounds. The purpose of this experiment is to determine the composition of calcium carbonate in limestone by performing gravimetric analysis which is finding the mass of a product or reactant through filtration. This will be accomplished through multiple reactions and multiple filtrations to isolate the calcium carbonate from the limestone. Gravity filtration and vacuum filtration are the two filtration methods that will be used. These will both help to separate many of the solids and precipitates from the aqueous solution. In order to determine the amount of calcium carbonate the following reactions are needed: CaCO

( ) + 2 HCl(aq) → H2O(l) + CO2(g) + CaCl2(aq)

3 s

CaCl2(aq) + (NH4)2SO4(aq) → CaSO4(s) + 2 NH4Cl(aq) These equations are very important and necessary in order to determine the calcium carbonate composition in limestone. The first reaction will produce a gas in the form of CO 2 and the mass of which can be used to calculate the mass of calcium carbonate through dimensional analysis. The second reaction will produce a solid. The mass of which will be calculated with the vacuum filtration and can be used to calculate the mass of calcium chloride in the reaction. Since both reactions involve calcium chloride you can convert from one equation to the other. Also percent composition is represented by:

A%=

Mass of A Mass of Substance

x 100%

This can be used to find the percentage of calcium carbonate in the limestone. Also a pH indicator will be used to help find the exact point that the solution goes from being acidic to becoming a basic solution. Materials: The materials needed can be found on page 78 of the lab manual (French, 2015). In addition to the materials listed, the following is also needed:     

Balance Filter paper Funnel Distilled water Watch glass

Procedure: Follow the procedure provided in the lab manual on pages 78-80 (French, 2015). The changes to the procedure include: 8.) Only add 5 drops of methyl red indicator instead of 10 drops 19.) Place watch glass in oven for 5 minutes. Remove from oven and allow to cool for 5 minutes. Record mass of watch glass with filter paper and contents. 20.) Omit step 20

Works Cited: 

French, April, Allison Soult, Stephen Testa, Pauline Stratman, M. Meral Savas, Fancois Botha, Carolyn Brock, Charles Griffith, Darla Hood, Robert Kiser, Penny O’Connor, William

Pluncknett, Donald Sands, Diane Vance, William Wagner. “CHE 111 General Chemistry Laboratory Manual.” 2015-2016 Edition. Pages 1-53. Print....