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separate sheet. 1. (6 points total The G-H or van t Hoff equations allow us to c

ID: 693278 • Letter: S

Question

separate sheet. 1. (6 points total The G-H or van t Hoff equations allow us to calculate DGo or K of a reaction as a function of temperature Consider the first dissociation step of H2S(aq): H,S(a) H,0) HS (a)+ HO (aq) a) (1 point) Write the expression for the dissociation constant, Ki of this weak acid (i.e., he equation for K as a function of concentrations of products and reactants) b) (3 points) Using the data in the thermodynamic tables, calculate Go, Kal, and pK,1 at 298K. Hint: treat the hydronium ion as H,O+H'(ag Answer: K, c) (2 points) Assuming calculate K at 90 °C to be independent of temperature,

Explanation / Answer

a) The equilibrium reaction is given as

H2S (aq) + H2O (l) <=======> HS- (aq) + H3O+ (aq)

The thermodynamic equilibrium constant, Ka,1 is the acid dissociation constant for the said reaction. The acid dissociation constant is given as

Ka,1 = [HS-][H3O+]/[H2S]

It is important to note that only the concentrations of aqueous species are included in the expression for the equilibrium constant. The concentrations of solid and liquid species are considered to be unity at equilibrium (ans).

b-c) I need the data in the thermodynamic tables; kindly provide the relevant information.