are six reactions to study in this part of the experiment. For each reaction, se
ID: 590417 • Letter: A
Question
are six reactions to study in this part of the experiment. For each reaction, select solutions the list of reagents to establish the equilibrium, that is, to produce ALL the species shown from in the equilibrium equation Once you have established the equilibrium, manipulate the concentrations in order to shift the equ librium first to the right and then to the left. Record your observations, verifying that the shift has eccurred and write the ionic equations to illustrate what is happening on a molecular level. Indicate the change in reaction rate (for the forward or reverse reaction) after each change that you induce in the equilibrium. Use small test tubes and minimal amounts of solutions; usually a few drops will suf- fice. Do not add more reagent than the minimum amount needed to change the equilibrium. If the concentration of a reagent becomes too great, you may not be able to shift again, or, unexpected side reactions may occur. If you keep your solution able to shift the equilibrium back and forth with relative ease. librium back onil, you should be 1. Reagents: 0.1 MK,Cr,0, 1 MHCI, I M NaOH 4 (aq) 17.11) orange yellow a. Dichromate ion produced by b. Equilibrium shifted to the right by c. Observation d. Net lonic Equation e. Reason for shift f. Equilibrium shifted to the le g. Observation h. Net Ionic Equation i. Reason for shift 2. Reagents: 0.1 MBaCl O.1 A FCK I MNH BaC204 (s) tr,ag) ·@ K.-?(EQ 17.12) white a. Bariurn oxa produ b. Net Ioni E Equilibrium shifted to the right by ervation e. Net fonic or ift qui ifted to the left by Equation i Reason for shift 17-169 Chemistry 141 Grossmont CollegeExplanation / Answer
Kc = [Ba2+][HC2O4-]/[H+] (the concentration of solid species is not included in the equilibrium expression)
a) Barium oxalate, BaC2O4 is produced by the reaction of BaCl2 and (NH4)2C2O4.
BaCl2 (aq) + (NH4)2C2O4 (aq) --------> BaC2O4 (s) + 2 NH4Cl (aq)
b) The aqueous species dissociate into ions The complete molecular equation is given below.
Ba2+ (aq) + 2 Cl- (aq) + 2 NH4+ (aq) + C2O42- (aq) -------> BaC2O4 (s) + 2 NH4+ (aq) + 2 Cl- (aq)
The net ionic equation for the reaction is obtained by cancelling out the common ions from both sides.
Ba2+ (aq) + C2O42- (aq) -------> BaC2O4 (s)
c) The equilibrium is shifted to the right by adding more H+.
d) The solubility of BaC2O4 in the aqueous solution increases by increasing the concentration of H+. There, more BaC2O4 becomes soluble and the mass of solid BaC2O4 decreases.
e) The net ionic equation is already provided in the question.
f) Kc is a thermodynamic equilibrium constant and hence, the value of Kc must remain unchanged at a particular temperature. When the H+ concentration is increased, the denominator in the expression for Kc increases. To keep Kc constant, the numerator must increase proportionately. Therefore, more Ba2+ and HC2O4- must be produced by the dissolution of BaC2O4, i.e, the reaction moves to the right.
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