Suppose you are studying coordination compounds of Co(II) with the ligand pyridine (py, C5H5N, MW = 79.10). You isolate a crystalline compound and since the only available ions are chloride and nitrate, you hypothesize the empirical formula of the coordinaton compound must be Co(II)w(py)x(Cl)y(NO3)z. you discover that the complex decomposes in water. you dissolve 0.1000g of the complex in water and add excess NaHg(SSN)4. after the precipitate washed and dried its mass is 0.1102g. how many grams of cobalt are contained in the 0.1000g of the complex?

Question

Suppose you are studying coordination compounds of Co(II) with the ligand pyridine (py, C5H5N, MW = 79.10). You isolate a crystalline compound and since the only available ions are chloride and nitrate, you hypothesize the empirical formula of the coordinaton compound must be Co(II)w(py)x(Cl)y(NO3)z. you discover that the complex decomposes in water. you dissolve 0.1000g of the complex in water and add excess NaHg(SSN)4. after the precipitate washed and dried its mass is 0.1102g. how many grams of cobalt are contained in the 0.1000g of the complex?

Answer 1

To determine the grams of cobalt contained in the 0.1000g of the complex, we need to follow a series of steps:

Step 1: Calculate the mass of the precipitate.
Given: Mass of the precipitate = 0.1102g

Step 2: Convert the mass of the precipitate to moles.
To convert the mass to moles, we need to know the molar mass of the precipitate.
The given compound NaHg(SSN)4 is sodium tetrathiomercurate(II). We need to find the molar mass using the periodic table or a chemical database.

The molar mass of sodium (Na) = 22.99 g/mol
The molar mass of mercury (Hg) = 200.59 g/mol
The molar mass of sulfur (S) = 32.06 g/mol
The molar mass of nitrogen (N) = 14.01 g/mol

Since each formula unit of NaHg(SSN)4 contains four moles of sulfur, we need to multiply the molar mass of sulfur by 4.
Molar mass of sulfur in NaHg(SSN)4 = 4 * 32.06 g/mol = 128.24 g/mol

The total molar mass of NaHg(SSN)4 =
22.99 g/mol (Na) + 200.59 g/mol (Hg) + 128.24 g/mol (S) + 4 * 14.01 g/mol (N)
= 22.99 g/mol + 200.59 g/mol + 128.24 g/mol + 56.04 g/mol
= 407.86 g/mol

Now we can convert the mass of the precipitate to moles:
Moles of precipitate = Mass / Molar mass
= 0.1102g / 407.86 g/mol

Step 3: Calculate the moles of cobalt in the complex.
Since the empirical formula of the complex is Co(II)w(py)x(Cl)y(NO3)z, it does not contain any cobalt. Therefore, the moles of cobalt in the complex are zero.

Step 4: Calculate the moles of cobalt in the 0.1000g of the complex.
Since the moles of cobalt in the complex are zero, there are no grams of cobalt contained in the 0.1000g of the complex.

Conclusion:
The 0.1000g of the complex does not contain any grams of cobalt.