CH141exp62009 - Analysis of a Chemical Mixture Using the...

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Analysis of a Chemical Mixture Using the Ideal Gas Law PRELAB: Reading : 1. Sections 10.4 & 10.6 of Brown, LeMay, Bursten, and Murphy. 2. This handout. Questions : Silver oxide can be decomposed to yield silver metal and oxygen gas according to the equation below. You conduct this reaction with an unknown mass of Ag 2 O, and collect 81.2 mL of O 2 over water. If the ambient temperature is 23 °C and the pressure is 751 mmHg, what mass of Ag 2 O did you start with? (The vapor pressure of water at 23 °C is 21.1 mmHg.) 2 Ag 2 O (s) 4 Ag (s) + O 2 (g) INTRODUCTION : The evolution of gas as part of a chemical reaction can be a useful feature in determining the identity, quantity, or purity of chemical compounds. For instance, given a mixture of two somewhat similar compounds in which only one will react and evolve gas in the presence of another specific reagent, the mass percentage of the compounds can be discerned by measuring the quantity of gas evolved in the reaction. In this lab you will be given a mixture of sodium chloride (NaCl) and sodium nitrite (NaNO 2 ) – the composition of this mixture will be ‘unknown’. You will quantitatively measure the amount of product formed by the reaction of one of the components under conditions where the other component is inert and does not react. One of the products of the reaction is a gas, which can be collected and its volume can be determined under measured conditions of pressure and temperature. The number of moles of gaseous product can be calculated using the Ideal Gas Law. The moles of product can be related to the moles and mass of the reactant from which the product was formed. By knowing the mass of the one component that reacted, the mass of the other component can then be determined by difference from the total mass of the chemical mixture tested. Finally, percent composition by mass can be calculated Each group will react the same sample three times, each time with an excess of sulfamic acid, HSO 3 NH 2 . The NaCl is unreactive under these conditions, whereas the NaNO 2 reacts to form nitrogen gas according to the reaction
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This note was uploaded on 02/09/2010 for the course CH CH242 taught by Professor Katz during the Spring '10 term at Colby.

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CH141exp62009 - Analysis of a Chemical Mixture Using the...

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