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# Precipitation formation test

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Question #1: If 200 mL of 0.300 M Cr(NO3)3(aq) is added to 100 mL of 4.0 * 10^-4 M NaF(aq) at 25 degrees celcius, will a CrF3 precipitate form? For CrF3 in water at 25°C, Ksp = 6.6 * 10^-11.

Question #2: The 3dxy orbital has its high probability regions lying between the x and y axes. The 3dz2 orbital has its high probability regions mainly on the z axis. The ligands in a complex ion with coordination number six lie on the x, y, and z axes. Which statement is true for the orbitals in this complex ion?
(a) The 3dxy and 3dz2 orbitals have the same energy.
(b) The 3dxy orbital has a higher energy than the 3dz2 orbital.
(c) The 3dxy orbital has a lower energy than the 3dz2 orbital.

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https://brainmass.com/chemistry/inorganic-chemistry/precipitation-formation-test-542338

#### Solution Preview

Q#1: 3 NaF + Cr(NO3)3 = 3 NaNO3 + CrF3
CrF3 <-> (Cr+3) + 3(F-1) [Cr+3 : cromium ion with +3 charge, F-1: Fluoride ion with -1 charge]

Before mixing, concentration of Cr ion, [Cr+3] ...

#### Solution Summary

In first problem, using given data it is estimated that whether in given reaction precipitation will be formed or not. In second problem corresponding to coordination number right answer is chosen

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