Percentage Composition, Empirical FORMULA AND Molecular Formula

Two elements, $\mathrm{X}$ (atomic weight $=75$) and $\mathrm{Y}$ (atomic weight $=16$) combine to give a compound having $75.8 \%$ of $\mathrm{X}$. The compound is:

What is meant by empirical and molecular formula of a compound? Explain with an example.

What is meant by empirical and molecular formula of a compound. How are the two related to each other?

A crystalline salt on being rendered anhydrous, loses $51.2 \%$ of its weight. The anhydrous salt on analysis gave the following percentage composition: $\mathrm{Mg}=20.0 \%;\mathrm{S}=26.66 \%;\mathrm{O}=53.33 \%$. Calculate the molecular formula of the anhydrous salt and the crystalline salt. Molecular mass of the anhydrous salt is $120$.

$1.615 \mathrm{g}$ of an anhydrous salt was placed in moist air. After a few days, it was found to be $2.875 \mathrm{g}$. Assuming that complete hydration has taken place, calculate the simplest formula of the hydrated salt. The percentage composition of anhydrous salt is: $\mathrm{Zn}=40.6 \%; \mathrm{S}=19.8 \%; \mathrm{O}=39.6 \%$.

A compound contains $4.07 \%$ hydrogen, $24.27 \%$ carbon and $71.65 \%$ chlorine. Its molar mass is $98.96 \mathrm{g}$. What are its empirical and molecular formulas?

The percentage composition of sodium phosphate as determined by analysis is $42.1 \%$ sodium, $18.9 \%$ phosphorus and $39 \%$ oxygen. Find the empirical formula of the compound.

An organic compound contains carbon, hydrogen and oxygen. $1.80 \mathrm{g}$ of the substance on combustion gave $2.64 \mathrm{g}$ of carbon dioxide and $1.08 \mathrm{g}$ of water. Calculate the empirical formula of the compound.

Calculate the percentage of water of crystallization in the sample of Blue Vitriol $({\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O})$.

Calculate the percentage composition of ethanol $\left({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\right)$.

The compound ${\mathrm{Na}}_2{\mathrm{B}}_4{\mathrm{O}}_7.10{\mathrm{H}}_2\mathrm{O}$ is commonly known as borax. Calculate the percentage of boron $\left(\mathrm{B}\right)$ in borax $(\mathrm{H}=1, \mathrm{B}=11, \mathrm{O}=16, \mathrm{Na}=23)$.