If 25 grams of CoCl2•H2O,2 being the subscript of cl and the h, was heated to constant weight. What mass of anhydrous salt would remain?

The easy way of doing this is

25.0g CoCl2.6H2O x (molar mass CoCl2/molar mass CoCl2.6H2O) = ?

To find the mass of anhydrous salt that would remain after heating, we need to understand the concept of hydrates and the process of dehydration.

A hydrate is a chemical compound that contains water molecules within its crystal structure, indicated by a dot followed by a specific number in the chemical formula. In this case, CoCl2•H2O is a hydrate, where H2O represents water molecules.

When a hydrate is heated, the heat energy causes the water molecules to evaporate, resulting in the formation of an anhydrous salt, which is the compound without any water molecules. The process of removing water through heating is called dehydration.

Given that we have 25 grams of CoCl2•H2O, we need to determine the mass of the anhydrous salt remaining after heating. We can find this by calculating the difference between the initial mass of the hydrate and the final mass after dehydration.

1. Determine the molar mass of CoCl2•H2O:
The molar mass of CoCl2 is 129.84 g/mol.
The molar mass of H2O is 18.02 g/mol.
The total molar mass of CoCl2•H2O is therefore:
(1 * 129.84 g/mol) + (1 * 18.02 g/mol) = 147.86 g/mol.

2. Calculate the moles of CoCl2•H2O:
The moles of CoCl2•H2O can be calculated using the formula:
Moles = Mass / Molar mass.
Moles = 25 g / 147.86 g/mol = 0.169 moles.

3. Determine the molar ratio between CoCl2 and anhydrous CoCl2:
Based on the chemical formula, for every one mole of CoCl2•H2O, one mole of CoCl2 is obtained after dehydration.

4. Calculate the mass of anhydrous CoCl2:
The mass of anhydrous CoCl2 can be calculated using the formula:
Mass = Moles * Molar mass.
Mass = 0.169 moles * 129.84 g/mol = 21.97 grams.

Therefore, after heating to constant weight, approximately 21.97 grams of anhydrous CoCl2 would remain.