Be as detailed as possible. Show examples if necessary. Thanks*
Lab B4 Le Châtelier's Principle Introduction All chemical reactions proceed until equilibrium is reached, provided none of the reactants or the products are removed from the reaction mixture. Le Châtelier's principle describes what happens to an equilibrium after it has been disturbed (Ebbing/Gammon, Sections 14.7, 14.8, and 14.9). 05 Purpose You will study the application of Le Châtelier's principle by seeing the effect of the addition of Fe and SCN-to an equilibrium mixture of Fe", SCN, and Fe(SCN)과, the effect of the addition of an acid to an equilibrium mixture of Ni2, NHs, and Ni(NH)% the effect of the addition of an acid and a base on the equilibrium involving an indicator; the effect of acids and bases on the solubility of Ca(OH)2 in water and the effect of temperature on an equilibrium mixture of Co', cr, and CoCla 2- New Substances In this experiment you will encounter some substances that you may not have seen before. The reaction between Fe and SCN (thiocyanate ion) gives Fe(SCN)2. This substance is a deeply colored complex ion. Other complex ions that you will encounter are Ni(NHs)6 and CoCl These substances result from the reaction between Ni? and NH3 and from the reaction between Co and CI, respectively. You will also study an equilibrium involving methyl orange, an indicator. Indicators are discussed in Appendix D. Read the second, third, and fourth paragraphs of that appendix to gain an understanding of the physical and chemical properties of this indicator. Concept of the Experiment Le Châtelier's principle can be described in the following way: "When a system in chemical equilibrium is disturbed by a change of temperature, pressure, or concentration, the system shifts in equilibrium composition in a way that tends to counteract this change of variable" (Ebbing/Gammon, Section 14.7). This statement explains the effects that you will encounter in this experiment. Procedure lib Getting Started 1. Obtain 3 small test tubes and a piece of filter paper Obtain directions for discarding the solutions that you will use in this experiment from your laboratory instructor. Be careful handling the solutions used in this experiment. 2. 3. CAUTION: Solutions of ammonia, hydrochloric acid, and sodium hydroxide can cause chemical burns, in addition to ruining your clothing. Do not use your finger as a stopper when mixing these solutions. If you spill any of these solutions on you, wash the contaminated area thoroughly and immediately report the incident to your laboratory instructor. You may require further treatment. May not be scanned, copied or duplicated, or posted to a publily accessible website, in whole or in part be o 2013 Cengage Leaming All Rights Reserved. custom page 125
