Question

# How do you find the molecular formula of a compound?

Open in App
Solution

## Molecular formula:A molecular formula is a chemical notation that indicates the number and kind of components present in a single molecule of a substance.The simplest form of the molecular formula is the empirical formula. It can figure out what amounts each constituent in the molecule should be in.The Molecular formula empirical$=$n$Ã—$empirical formula, where n is an integer multiple. Example: For calculating molecular formula let us take a compound having $49.48%$carbon, $5.19%$hydrogen,$16.48%$ oxygen, and $28.85%$ nitrogen. The molecular weight of the compound$=194.19\mathrm{g}{\mathrm{mol}}^{-1}$. Step 1: Calculating the weight of the particular atomMultiplying percent composition by weight we get, Carbon$=194.19Ã—0.4948â‡’96.0852$Hydrogen$=194.19Ã—0.0519â‡’10.0784$Oxygen$=194.19Ã—0.1648â‡’32.0025$Nitrogen$=194.19Ã—0.2285â‡’56.0238$Step 2: Dividing each value by its atomic weightCarbon$=\frac{96.0852}{12.011}â‡’7.9997$Hydrogen$=\frac{10.0784}{1.008}â‡’9.998$Oxygen $=\frac{32.0025}{15.9994}â‡’2.000$Nitrogen$=\frac{56.0238}{14.0067}â‡’3.9997$Step 3: Rounding off to the closest whole number: Carbon$=7.997â‰ˆ8$Hydrogen$=9.998â‰ˆ10$Oxygen$=2$Nitrogen$=3.997â‰ˆ4$Step 4: Writing molecular formula:Write each value of the whole number along with its atom. We get the molecular formula as${\mathrm{C}}_{8}{\mathrm{H}}_{10}{\mathrm{O}}_{2}{\mathrm{N}}_{4}$.

Suggest Corrections
12
Join BYJU'S Learning Program
Related Videos
Empirical and Molecular Formula
CHEMISTRY
Watch in App
Join BYJU'S Learning Program