Chem 142 - Lab 2 - Composition of Compounds

Chem 142 - Lab 2 - Composition of Compounds - Name: Alice...

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Name: Lab Partner: Alice Hsieh Hieu Duong EXPERIMENT 2: Chemical Composition of Compounds I. IDENTIFICATION BASED ON PERCENT METAL COMPOSITION DATA I. Magnesium Mass of empty crucible and cover: 21.96 g Mass of crucible, cover, and Mg: 22.16 g Mass of Mg: 0.2 g Mass of crucible, cover, and product: 22.29 g Mass of product: 0.32 g II. Copper Mass of empty crucible and cover: 21.12 g Mass of crucible, cover, and sample: 22.13 g Mass of sample: 1.01 g Mass of crucible, cover, and product: 21.82 g Mass of product: 0.7 g Mass of crucible and cover : 21.94 g Mass of crucible, cover, and KCl/KClO3 mixture: 22.94 g Mass of KCl/KClO3 mixture: 1 g Mass of crucible, cover, and product: 22.59 g Mass lost upon heating : 0.35 g II. DETERMINATION OF PERCENT KClO 3 IN A KClO 3 /KCl MIXTURE III. KCl/KClO 3 mixture Purpose and Method Things to think about: What is the goal of this experiment? Explain how it is accomplished. What is the general method (not step by step detailed procedure) that you will be using to achieve this goal? How will you process the data that you record in lab? (What calculations will you use and how do you obtain all of the values to plug into those equations?) In this experiment, Mg is strong heated until it fully reacts with a component of air (oxygen or nitrogen). Explain how percent Mg is determined. Also explain how percent Mg is used to distinguish between MgO and Mg 3 N 2 . (2 pts) The percent Mg is determined by taking the mass of magnesium strip in the beginning on the lab and divide it by the mass of product, then times 100. The mass of Mg strip is measured in the beginning of the the experiment and the product is measured after. Because we can calculate the theoretical % composition of Mg in magnesium oxide and magnesium nitride, we can compare the experimented value with them to distinguish between magnesium oxide and magnesium nitride. How is percent Cu determined in the copper carbonate hydroxide compounds? (2 pts) When carbon carbonate hydroxide compounds are heated, one of the products is copper oxide. However, the moles of CuO produced in the 2 different types of copper carbonate hydroxide compounds are different. Therefore, by calculating the % composition of Cu in the original sample and comparing it to the theoretical composition of copper in the 2 kinds of carbonate hydroxide compounds, we can determine which copper carbonate hydroxide compound we had. How is percent KClO 3 in a KClO 3 /KCl mixture determined? (2 pts) As the mixture is heated, the products are potassium chloride and oxygen gas. Knowing the mass of product that is lost, we can find the mass of KCl in the sample through stoichiometry because we know the balanced equation of the reaction: 2KClO 3 --> 2KCl + 3O 2 We ca nthen divide this value by the mass of original sample to find the % composition of
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This note was uploaded on 10/27/2010 for the course CHEM 142 taught by Professor Zoller,williamh during the Winter '07 term at University of Washington.

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Chem 142 - Lab 2 - Composition of Compounds - Name: Alice...

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