Saturday

April 18, 2015

April 18, 2015

Posted by **Anonymous** on Sunday, May 6, 2012 at 9:15pm.

Please help, I don't know how to do this problem.

- chemistry -
**DrBob222**, Sunday, May 6, 2012 at 10:25pmHere is how you do this with a little chicanery. First, we assume the reaction goes to completion to the right. That's not a bad assumption considering the size of the formation constant.

.........Co^2+ + 4NH3 ==> Co(NH3)4^2+

Initial.0.140....1.2........0

change...-0.140.-4*1.2.....0.140

equil.....0.......0.64......0.140

Actually, this isn't at equilibrium since we drove it to completion. Therefore, the numbers above are a little TOO far for equilibrium; therefore, it must move back to the left. How much will it move? We set up another set of conditions but start with where we ended above.

..........Co^2+ + 4NH3 ==> Co(NH3)4^2+

I.........0.......0.64......0.140

C.........+x......+4x.......-x

E.........x.....0.64+4x.....-x

Substitute into K.

K = [Co(NH3)4^2+]/[Co^2+][MH3]^4

5E31 = [0.140-x][x][0.64+4x]^4

Now assume 0.140-x = 0.140 and assume 0.64+4x = 0.64 and solve for x = (Co^2+). It's a very small number.

**Answer this Question**

**Related Questions**

Chemistry - A 0.140-mole quantity of CoCl2 is added to a liter of 1.20 M NH3 ...

Chemistry - A 0.130-mole quantity of CoCl2 is added to a liter of 1.20 M NH3 ...

Chemistry - A 0.130-mole quantity of CoCl2 is added to a liter of 1.20 M NH3 ...

Chemistry - A 0.170-mole quantity of CoCl2 is added to a liter of 1.20 M NH3 ...

Chem - A 0.170-mole quantity of NiCl2 is added to a liter of 1.20 M NH3 solution...

Chemistry - The formation constant of [M(CN)4]^-2 is 7.70 × 10^16, where M is a...

Chemistry - The formation constant of [M(CN)6]4– is 2.50 × 1017, where M is a ...

chemistry - The formation constant of [M(CN)6]4– is 2.50 × 1017, where M is a ...

Chemistry - in the presence of NH3, Cu+2 forms the complex ion [Cu(NH3)4]+2. If ...

college chem - The cation M2+ reacts with NH3 to form a series of complex ions ...