CH141Lab3fall2009

CH141Lab3fall2009 - The Reaction of Calcium Chloride with...

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The Reaction of Calcium Chloride with Carbonate Salts PRE-LAB ASSIGNMENT : Reading: Chapter 3 & Chapter 4, sections 1-3 in Brown, LeMay, Bursten, & Murphy. 1. What product(s) might be expected to form when solid lithium carbonate is added to an aqueous solution of calcium chloride? Write a balanced chemical equation for this process. 2. How many grams of lithium carbonate would you need to fully react with one mole of calcium chloride? Please show your work. INTRODUCTION : The purpose of this lab is to help you discover the relationships between the reactants and products in a precipitation reaction. In this lab you will react a calcium chloride solution with lithium carbonate, sodium carbonate, or potassium carbonate. The precipitate that results will be filtered and weighed. In each determination you will use the same amount of calcium chloride and different amounts of your carbonate salt. This experiment is a "discovery"- type experiment. The procedure will be carefully described, but the analysis of the data is left purposely vague. You will work in small groups to decide how best to work up the data. In the process you will have the chance to discover some principles, to use what you have learned in lecture, and to practice thinking about manipulative details and theory at the same time. Plotting your data in an appropriate manner should verify the identity of the precipitate and clarify the relationship between the amount of carbonate salt and the yield of precipitate. Predicting the formulas of ionic compounds . Compounds like calcium chloride (CaCl 2 ) and sodium carbonate (Na 2 CO 3 ) are ionic substances. Soluble ionic substances dissociate in aqueous solution to form ions as shown below for calcium chloride. CaCl 2 (aq) Ca 2+ (aq) + 2 Cl (aq) A list of common ions is given in your text. A short excerpt is tabulated below. The charges on the ions can be used to predict the formulas of ionic compounds as the ions combine to give electrically neutral compounds. For example, the combination of K + and PO 4 3– would give K 3 PO 4 , which has a net charge of zero. If more than one polyatomic ion such as nitrate ion is needed to balance the charge, it is enclosed in parentheses with the number of times it occurs indicated with a subscript to the right of the parentheses, for example, in calcium nitrate, Ca(NO 3 ) 2 . Some Common Ions Cations Anions H + hydrogen ion OH hydroxide ion Na + sodium ion Cl chloride ion K + potassium ion CO 3 2– carbonate ion Ca 2+ calcium ion NO 3 nitrate ion Ag + silver ion PO 4 3– phosphate ion NH 4 + ammonium ion SO 4 2– sulfate ion Predicting the product of precipitation reactions . Sometimes a precipitate results when two soluble ionic compounds are mixed in aqueous solution. For example, a precipitate is formed when solutions of silver nitrate and sodium chloride are mixed. How would you predict the identity of the precipitate? This can be done in two steps. First, break the parent compounds into their respective ions, and then exchange the ions between partners to predict the
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CH141Lab3fall2009 - The Reaction of Calcium Chloride with...

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