23. A compound has 0 = 61.32%, S 61-32%, S = 11.15%, H = 4.88% and Zn mon compound is 287 a.m.u. Find the molecular formula of the compound, assuming that all the hydrogen is present as water of crystallisation.
Answers
Explanation:
To solve this question firstly we calculate its molecular formula.
For finding the molecular formula of the compound we have to follow the following rules:
• Firstly, write down the mass percentage of the constituent elements.
• Then, write the atomic masses of those elements.
• Now, divide the percentage of each element with its atomic mass.
• Then, finally divide all the values by the smallest value obtained.
• This will give you the simplest molecular formula of the compound.
The table for calculating the molecular formula of the compound is given below:
Element percentage Atomic Mass Ratio=percentageAtomicMass Simplest Ratio
Zn 22.65 65 22.6565=0.34 0.340.34=1
S 11.15 32 11.1532=0.34 0.340.34=1
O 61.32 16 61.3216=3.83 3.830.34=11
H 4.88 1 4.881=4.88 4.830.34=14
As it is given in the question that all the atoms of hydrogen are present as water of crystallization. So, 7atoms of oxygen are in combination with hydrogen as water of crystallization and the remaining 4 atoms are in combination with sulfur as sulfate.
So, molecular formula of the compound will beZnSO4.7H2O
. This formula can be verified by calculating its molecular mass: 65 + 32 + 4(16) + 7(18) = 287 u.
As, this mass is equal to relative molecular mass.
Note:
Without determining the molecular formula of a compound, nomenclature is not possible for that compound. So, the molecular formula of a compound plays a vital role in the naming convention of any compound.