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Combining Equilibrium Equations

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Please provide solution for (a) and (b) with explanation of how it was derived.

Early groups used Pb plumbing in their homes more than 2000 years ago. This Pb pipe has since corroded in the soil to form cerrusite (PbCO3) and hydrocerrusite ( Pb3(CO3)2(OH)2 ).

Essington et al., 2004. The soil mineralogy of lead at Horaceʼs
Villa. Soil Sci. Soc. Am. J., 68, 979)

(a) Assuming a CO2 partial pressure in the soil of about 0.02 atm , calculate the free lead ion solubility, (Pb2+), in soil solution at pH 5, 6, 7 and 8.

(b) Plot the calculated log (Pb2+) versus pH for these minerals on the same graph, with pH on the x-axis.

Reaction Equilibrium Constants :

PbCO3(s) + 2H+ = Pb2+ + CO2(g) + H2O log Ko = 4.89

Pb3(CO3)2(OH)2(s) + 6H+ = 3 Pb2+ + 2 CO2(g) + 4 H2O log Ko = 18.49

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Solution Summary

This solution demonstrates how to combine two equilibrium equations and solve for various concentrations under different conditions.

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LeChatelier's Principle, Equilbrium and Combined Gas Law

Calculate Keq for the following (equilibrium concentrations given below substances)

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[6.0 x 10-1] [0.21]

b) 2 CO2 (g) + heat ↔ 2 CO (g) + O2 (g)
[0.103] [0.024] [1.18 x 10-2]

c) NO2 (g) + O2 (g) + heat ↔ NO (g) + O3 (g)
[0.072] [0.083] 6.73 x 10-2] [6.73 x 10-2]

2. For all three of the equilibria in problem #1 predict (1) how Keq is affected by an increase in temperature, (2) predict how the equilibrium will shift when pressure is decreased, (3) predict how the equilibrium will shift when the concentration of the underlined substance is increased, and (4) predict how the equilibrium will shift when the temperature is decreased.

Next set 4.5

How many grams of CO2 would be formed from 30 grams of C4H10 in the following reaction?
Be sure to balance the reaction before proceeding.
C4H10 + O2 → CO2 + H2O

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