a compound consist of carbon,hydrogen and oxygen only.the percentage by mass are carbon 40.0% and 6,7% hydrogen.calculate the empirical formulae
To calculate the empirical formula of a compound, we need to determine the ratio of atoms in the compound. In this case, we have the percentages of carbon and hydrogen.
1. Assume we have 100 grams of the compound. This will allow us to convert the percentages into grams.
Carbon:
40.0% of 100 grams = 40.0 grams (C)
Hydrogen:
6.7% of 100 grams = 6.7 grams (H)
2. Next, convert the grams of each element into moles by using their respective molar masses:
Carbon (C):
- Molar mass of carbon (C) = 12.01 g/mol
- Moles of carbon = grams of carbon / molar mass of carbon
= 40.0 g / 12.01 g/mol
≈ 3.33 moles
Hydrogen (H):
- Molar mass of hydrogen (H) = 1.01 g/mol
- Moles of hydrogen = grams of hydrogen / molar mass of hydrogen
= 6.7 g / 1.01 g/mol
≈ 6.63 moles
3. Divide each of the moles obtained in step 2 by the smallest number of moles to obtain a simple, whole-number ratio:
Carbon: 3.33 moles / 3.33 ≈ 1 mole (C)
Hydrogen: 6.63 moles / 3.33 ≈ 2 moles (H)
4. Round off the ratio obtained to the nearest whole number.
The empirical formula for the compound with the given percentage composition is CH2.