After 0.6523g of CoCL2 .6H2O is heated, the residue has a mass of 0.3423g. Calculate the percent H2O in the hydrate. What is the formula of the hydrate
mass H2O in sample = 0.6523 - 0,3423 = ?
% H2O = (mass H2O/mass sample)*100 = ?
mols H2O = grams/molar mass = ?
mols CoCl2 = grams/molar mass = ?
convert to ?mols H2O/1 mol CoCl2 and formula will be CoCl2.?H2O in 1 mol CoCl2.
Post your work if you get stuck.
To calculate the percent H2O in the hydrate, you need to find the mass of H2O in the original hydrate as well as the total mass of the hydrate.
First, you need to find the mass of H2O in the original hydrate. To do this, subtract the mass of the residue from the mass of the original hydrate:
Mass of H2O = Mass of original hydrate - Mass of residue
Mass of H2O = 0.6523g - 0.3423g
Mass of H2O = 0.31g
Next, you need to find the total mass of the hydrate by adding the mass of the residue to the mass of H2O:
Total mass of hydrate = Mass of H2O + Mass of residue
Total mass of hydrate = 0.31g + 0.3423g
Total mass of hydrate = 0.6523g
Now, you can calculate the percent H2O in the hydrate by dividing the mass of H2O by the total mass of the hydrate and multiplying by 100:
Percent H2O = (Mass of H2O / Total mass of hydrate) * 100
Percent H2O = (0.31g / 0.6523g) * 100
Percent H2O ≈ 47.50%
To determine the formula of the hydrate, you need to use the molar masses of the elements involved. The formula of the hydrate can be written as CoCl2 • xH2O, where x is the number of moles of H2O per mole of CoCl2.
The molar mass of CoCl2 = atomic mass of Co + 2 * atomic mass of Cl
Molar mass of CoCl2 = 58.93 g/mol + 2 * 35.45 g/mol
Molar mass of CoCl2 = 129.83 g/mol
Since the mass ratio of CoCl2 to H2O in the hydrate is 1:1, the number of moles of CoCl2 is equal to the number of moles of H2O.
Number of moles of CoCl2 = Mass of CoCl2 / Molar mass of CoCl2
Number of moles of CoCl2 = 0.3423g / 129.83 g/mol
Number of moles of CoCl2 ≈ 0.00264 mol
Therefore, the formula of the hydrate is CoCl2 • 0.00264 H2O, which can be simplified as CoCl2 • 2.64H2O.