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Empirical Formula Notes
Definition:
What does it mean?
When do you have empirical formula:
Step to Calculate Empirical Formula
1. Change mass percent (%) to actual masses or use given masses directly
- Assume 100.g compound (cpd)
2. Change mass of element to mole of element
3. Change moles to molar ratio.
- Take smaller mole number and divide this number into all other mole number.
4. If all numbers are not whole, you need to determine a single number that you can multiple to all mole numbers so that the resultant number are ALL WHOLE.
- Need to determine which number. The key is the following decimal to fraction conversion.
- 1/6 (0.167)
- 1/5 (0.200)
- 1/4 (0.250)
- 1/3 (0.333)
- 2/5 (0.400)
- 1/2 (0.500)
- 3/5 (0.600)
- 2/3 (0.666)
- 3/4 (0.750)
- 4/5 (0.800)
- 5/6 (0.830)
Example from board
What is the Empirical Formula (EF) of the compound that is 25.9% nitrogen and 74.1% oxygen? (In other words, for NxOy, solve for x and y)