Question

A hydrate is determined to be 45.43% water and 54.57% CoCl. Find the chemical formula and name
for this hydrate. (*Hint - assume that there is 100 g total of hydrate compound.)

Answer 1

Answer:

Chemical formula is CoCl. 3H₂O

Explanation:

Data Given

Percentage of water = 45.43%

Percentage of CoCl. = 54.57%

Chemical Formula of the hydrates = ?

Solution:

First, find the mass of each of the part ( CoCl and water) in 100 g of the Compound.

Mass of CoCl = 28 + 35.5

Mass of CoCl = 63.5

Mass of H₂O = 18 g

Now find how many moles are there for each element in 100 g of compound

So,

The percentage will be count in grams for 100g in compound

Find the moles in total compounds

Formula Used for CoCl

mole of CoCl = mass of CoCl / Molar mass of CoCl

mole of CoCl = mole of  54.57 g / 63.5 g/mol

mole of CoCl = 0.859

Formula Used for H₂O

mole of H₂O = mass of H₂O/ Molar mass ofH₂O

mole of H₂O = 45.43 g / 18 g/mol

mole of  H₂O = 2.539

Now

To find the Chemical formula

Divide each one by the smallest number of moles

CoCl = 0.859 / 0.859

CoCl = 1

For H₂O

H₂O = 2.539  / 0.859

H₂O = 3

Multiply the mole fraction to a number to get the whole number.

CoCl =  1

H₂O  = 3

So,  

The Chemical formula is CoCl. 3H₂O