HELP. test on a problem exactly like this tomorrow. 2 HgCl2(aq) +H2 C2O4 2HCl +

Question

HELP. test on a problem exactly like this tomorrow.

2 HgCl2(aq) +H2 C2O4 2HCl + 2 CO2 + Hg2Cl2/aq) The equation for the reaction between mercuric chloride and oxalic acid in hot aqueous solution is shown above. The reaction rate may be determined by measuring the initial rate of formation of hydrogen chloride, at constant temperature, for various initial concentrations of mercuric chloride and oxalate as shown in the following table According to the data shown, what is the rate law for the reaction above? On the basis of the rate law determined in part (a), calculate the specific rate constant. Specify the units. What is the numerical value for the initial rate of disappearance of H2C2O4 for Experiment1 Calculate the initial oxalic acid ion concentration for Experiment 4. Use the information below and in your text to determine if the above reaction is spontaneous (calculate DH and DS and use them to calculate DG at 90 degree C) thermo data for oxalic -450kJ and 120j/mol-K> Mercury(I) chloride Hg2C12 -586 kJ and 78J/mole-K

Explanation / Answer

A)

a)Let us assume a rate law ,

r = K[Hg Cl2]^a[H2C2O4]^b

r is the rate of formation of HCl, K is rate constant.

for 1, 0.52*10^-4 = K 0.0836^a 0.202^b --->(1)

for 2, 2.08*10^-4 = K 0.0836^a 0.404^b--->(2)

for 3, 1.06*10^-4 = K 0.0418^a 0.404^b--->(3)

dividing 1 by 2

we get 0.25 = 0.5^b

so b= 2

dividing 2 by 3

we get 1.962 = 2^a

so a = 0.9725

rate law, r = K [Hg Cl2]^0.9725 [H2C2O4]^2

b)substituting a , b values in (1) we get K= 0.0142 mol^-1.9725 lit^1.9725 min ^-1

units are mol^-1.9725 lit^1.9725 min ^-1

c)initial rate of dissapearence of oxalic acid = 0.5(rate of formation of HCl ) = 0.5*0.52*10^-4 = 0.26 mol L-1 min -1

d)numerical value

r = 0.0142 [Hg Cl2]^0.9725 [H2C2O4]^2

1.27*10^-4 = 0.0142 [0.0316]^0.9725 [H2C2O4]^2

so, [H2C2O4] = 0.507 mol L-1

numerical value , initial conc of oxalic acid = 0.507 M

B)delta G of rxn = delta G of products - delta G of reactants

delta G = delta H - T delta S

delta G of products = delta G of Hg2Cl2 = -586 Kj - 78*363 j = -614.314 KJ/mol

delta G of reactants - delta G of oxalic acid = -450KJ - 120*363J = -493.56 KJ/mol

delta G of rxn = -614.314 - (-493.56 )= -120.754 KJ/mol

-120.754 KJ/mol is delta G

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