given equations: rocedure omplete Table 1 below before beginning the experiment.
ID: 562413 • Letter: G
Question
given equations:
rocedure omplete Table 1 below before beginning the experiment. Ise the thermodynamic data table on the following page to help you calculate and fill out Table 1. Write the salt/ppt equation for each precipitation reaction indicated. AgCl(s) formation is shown as an example. Waters of hydration are included in the reaction. Calculate G° for each reaction. · . waters of hydration are included in the calculation for G Note that for PbCl2 and Ba(NO3)2 you will need to use 11 and S values to determine G. Also note that for these two compounds, you need to calculate G at 3 temperatures. o Calculate AGxn for each solid that might precipitate when equal volumes of a 0.2 M cation solution and a 0.2 M anion solution are mixed together. Based on your results for AGan predict whether you will observe a precipitate during the experiment.Explanation / Answer
When equal volumes of 0.2 M cation & anion are mixed,
[cation] = [anion] = 0.2 M / 2 = 0.1 M
Room temperature, T = 298 K
Gas constant, R = 8.314 J/mol-K
1.
Ag+ + Cl- --> AgCl
Q = [AgCl]/([Ag+][Cl-])
Q = 1 / (0.1 * 0.1) = 100
R T ln(Q) = 8.314 * 298 * ln(100) / 1000
= 11.41 kJ
Goprod = -109.789 kJ
Goreact = 77.01 – 131.228 = -54.218 kJ
Gorxn = Goprod - Goreact = -55.571 kJ
Grxn = Gorxn + R T ln(Q) = -55.571 + 11.41 kJ = -44.16 kJ
Since Grxn < 0, precipitation will occur
2.
Ag+ + I- --> AgI
Q = [AgI]/([Ag+][I-])
Q = 1 / (0.1 * 0.1) = 100
R T ln(Q) = 8.314 * 298 * ln(100) / 1000
= 11.41 kJ
Goprod = -66.19 kJ
Goreact = 77.01 – 51.57 = 25.44 kJ
Gorxn = Goprod - Goreact = -91.63 kJ
Grxn = Gorxn + R T ln(Q) = -91.63 + 11.41 kJ = -80.22 kJ
Since Grxn < 0, precipitation will occur
3.
2 Ag+ + SO42- --> Ag2SO4
Q = [Ag2SO4]/([Ag+]2[SO42-])
Q = 1 / (0.12 * 0.1) = 1000
R T ln(Q) = 8.314 * 298 * ln(100) / 1000
= 17.11 kJ
Goprod = -618.41 kJ
Goreact = 2 * 77.01 - 744.53 = - 590.51 kJ
Gorxn = Goprod - Goreact = -27.9 kJ
Grxn = Gorxn + R T ln(Q) = -27.9 + 17.11 kJ = - 10.79 kJ
Since Grxn < 0, precipitation will occur
4.
Ba2+ + 2 Cl- + 2 H2O à BaCl2.2H2O
Q = [BaCl2.2H2O]/([Ba2+][Cl-]2[H2O]2)
Q = 1 / (0.1 * 0.12 * 1) = 1000
R T ln(Q) = 8.314 * 298 * ln(1000) / 1000
= 17.11 kJ
Goprod = -1296.32 kJ
Goreact = - 560.77 + 2 * (-131.228) + 2 * (-237.129) kJ = -1297.484 kJ
Gorxn = Goprod - Goreact = 1.164 kJ
Grxn = Gorxn + R T ln(Q) = 1.164 + 17.11 kJ = 18.28 kJ
Since Grxn > 0, precipitation will not occur
5.
Ba2+ + 2 NO3- à Ba(NO3)2
Q = [Ba(NO3)2]/([Ba2+][ NO3-]2)
Q = 1 / (0.1 * 0.12) = 1000
R T ln(Q) = 8.314 * 298 * ln(1000) / 1000
= 17.11 kJ
Goprod = -796.59kJ
Goreact = -560.77 + 2 * (-108.74) kJ = -778.25 kJ
Gorxn = Goprod - Goreact = -18.34 kJ
Grxn = Gorxn + R T ln(Q) = -18.34 + 17.11 kJ = -1.23 kJ
Since Grxn < 0, precipitation will not occur
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