Question

each copper(ii) sulfate unit is associated with five water molecules in crystalline copper(ii) sulfate pentahydrate (cuso₄·5h₂o). when this compound is heated in air above 100°c, it loses the water molecules and its blue color:
cuso₄·5h₂o → cuso₄ + 5h₂o
(blue compound)
if 14.68 g of cuso₄ remain after heating 19.12 g of the blue compound, calculate the number of moles of h₂o originally present in the compound.
round your answer to 3 significant digits.
moles of water

Explanation:

Step1: Calculate the mass of water lost

Mass of water lost \(m = 19.12\space g-14.68\space g = 4.44\space g\)

Step2: Calculate the molar mass of \(H_2O\)

The molar mass of \(H_2O\), \(M=(2\times1 + 16)\space g/mol=18\space g/mol\)

Step3: Calculate the number of moles of \(H_2O\)

Using the formula \(n=\frac{m}{M}\), where \(m\) is the mass and \(M\) is the molar mass.
\(n=\frac{4.44\space g}{18\space g/mol}=0.247\space mol\)

Answer:

\(0.247\)