What is the expected mass of anhydrous salt formed after the waters of hydration of CoCl2·6H2O are driven off completely by heating, resulting in a mass loss of 2.000 g water?
What is the colour of lead
Bluish-white color
To find the expected mass of the anhydrous salt formed after driving off the water of hydration, we need to use the concept of stoichiometry.
The formula of the hydrated salt given is CoCl2·6H2O. This means that each formula unit of the hydrated salt contains 6 water molecules.
Given that there was a mass loss of 2.000 g water, we can calculate the molar mass of water (H2O = 18.015 g/mol) and convert the mass loss to moles:
2.000 g water / 18.015 g/mol = 0.11091 mol water
Since the ratio of water molecules to the hydrated salt is 6:1, we can now determine the moles of the hydrated salt before heating:
0.11091 mol water * (1 mol hydrated salt / 6 mol water) = 0.01849 mol hydrated salt
To find the expected mass of the anhydrous salt, we need to know its molar mass. The molar mass of CoCl2 can be found using the periodic table:
Co: 58.933 g/mol
Cl: 35.453 g/mol (x2 for CoCl2 = 70.906 g/mol)
Adding the molar masses of CoCl2 and subtracting the mass of the water:
70.906 g/mol + 0.01849 mol * 18.015 g/mol = 71.253 g/mol
Therefore, the expected molar mass of the anhydrous salt formed is 71.253 g/mol.
CoCl2·6H2O ----> CoCl2(s) + 6H20(g)
****H2O is lost as a gas.
2g of H20*(1 mole/18 g of H2O)=moles of H20
moles of H2O*(1 mole of CoCl2/6 moles of H20)= moles of CoCl2
moles of CoCl2*(129.89g/1 mole)= mass of CoCl2