Answer:
The correct answer is MgCO₃.5H₂O.
Explanation:
Based on the given information,
The mass of hydrate of magnesium carbonate given is 15.67 grams, and the mass of anhydrous magnesium carbonate given is 7.58 grams.
Now the mass of water will be,
= 15.67 grams – 7.58 grams
= 8.09 grams
The molecular mass of magnesium carbonate is 84.32 grams, the moles of MgCO₃ can be determined by using the formula,
Number of moles = Mass/Molecular mass
Moles of MgCO₃ = 7.58/84.32
= 0.0898 moles
Similarly, the number of moles of water will be,
Moles of H₂O = 8.099/18.02
= 0.4489 moles
After getting the values, there is a need to choose the smaller value and use it to divide both the values to get the ratio,
MgCO₃ = 0.0898/0.0898 = 1
H₂O = 0.4489/0.0898 = 4.9 or 5
Thus, the molecular formula for the hydrate will be MgCO₃.5H₂O.
