Final answer:
The mass of water lost during heating is 0.287 g.
Step-by-step explanation:
To calculate the mass of water lost during heating, we need to find the mass of water in the initial compound before heating and subtract the mass of the residue after heating.
The mass of water in CoCl2 • 6H2O is calculated by multiplying the molar mass of water (18.015 g/mol) by the coefficient of water (6), which gives a total mass of 108.09 g/mol.
The mass of water lost during heating is obtained by subtracting the mass of the residue (0.343 g) from the initial mass of water in the compound (0.63 g), resulting in a mass loss of 0.287 g.