Can someone please help me with these two Chemistry questions? 1.) At any given

Question

Can someone please help me with these two Chemistry questions?

1.) At any given temperature, the equilibrium constant for the formation of iron (III) thiocyanate was found to be 115.7. Determine the concentration of the iron (III) nitrate, if the concentration of iron( III) thiocyanate is 0.0000191 M and the concentration of the thiocyante ion is 0.000203 M.

2.)

Calculate the concentration of Fe(SCN)2+ in the solution below.

Fe3+ (aq) + SCN– (aq) FeSCN2+ (aq)

Beaker number

Beaker number

0.200 M Fe(NO3)3
(mL) 0.00200 M SCN–
(mL) H2O
(mL) Concentration Fe(SCN)+2 1 8.95 5.73 30.59

Explanation / Answer

1) Equilibrium constant = K = 115.7

The reaction is:

Fe3+ + SCN- -----> Fe(SCN)2+

[SCN-] = 0.000203 M

[Fe(SCN)2+] = 0.0000191 M

K = [Fe(SCN2+]/([Fe3+][SCN-])

115.7 = 0.0000191/([Fe3+]*0.000203)

[Fe3+] = 0.000813 M

concentration of iron(III) nitrate = 0.000813 M

2) moles of Fe(NO3)3 in solution = 0.00895*0.200 = 0.00179 mol

moles of SCN- in solution = 0.00573*0.00200 = 1.146*10-5 mol

Out of Fe(NO3)3 and SCN-, SCN- is limiting reagent.

So, moles of Fe(SCN)2+ = moles of SCN- = 1.146*10-5 mol

total volume = 8.95+5.73+30.59 = 45.27 ml = 0.04527 L

concentration of Fe(SCN)2+ = moles/volume = 1.146*10-5/0.04527 = 2.53*10-4 M

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