How do you calculate empirical and molecular formulas in Class 11 Chemistry?
Answer (1)
Here's the process:
- Percent to Mass: If given percentages, assume you have 100g of the compound. Convert the percentages directly to grams.
- Mass to Moles: Convert the mass of each element to moles by dividing by its molar mass.
- Divide by Smallest: Divide each mole value by the smallest mole value obtained in the previous step. This will give you the simplest whole-number ratio of the elements.
- Multiply Until Whole: If the ratios are not whole numbers, multiply all ratios by the smallest possible integer that will convert them to whole numbers. Common fractions to look for are 0.5, 0.33, and 0.25.
- Empirical Formula: The whole-number ratios obtained in the previous step represent the subscripts in the empirical formula.
-
Molecular Formula (if given molar mass):
- Calculate the empirical formula mass.
- Divide the molecular mass (given in the problem) by the empirical formula mass. This gives you a whole number, 'n'.
- Multiply the subscripts in the empirical formula by 'n' to obtain the molecular formula.
Comments (0)
