9 grams of carbon and 1.5 grams of hydrogen combined with oxygen to make a compond whose mass is 22.5 and whose relative molecular mass is 60.determine the molecular formula
then grams oxygen is 22.5-9-1.5 grams O
Now calculate the moles of
C
H
O
Divide them all by the lowest denominator, the whole numbers you get is the empirical formula.
Find the mol mass of the empirical formula. divide that into 60. THat ratio is what each subscript needs to be multiplied by to get the molecular formula.
Post what you have, and we will critique it.
To determine the molecular formula, we need to find the empirical formula first, and then calculate the molecular formula based on the relative molecular mass.
1. Find the moles of each element:
- Carbon (C): Convert grams to moles using the molar mass of carbon (12 g/mol).
moles of C = mass of C / molar mass of C = 9g / 12 g/mol = 0.75 mol
- Hydrogen (H): Convert grams to moles using the molar mass of hydrogen (1 g/mol).
moles of H = mass of H / molar mass of H = 1.5g / 1 g/mol = 1.5 mol
- Oxygen (O): Calculate the remaining moles of oxygen by subtracting the total moles of C and H from the total moles in the compound.
moles of O = total moles - moles of C - moles of H
moles of O = 60 g / (molar mass of O) - 0.75 mol - 1.5 mol
2. Calculate the simplest whole number ratio of atoms:
Divide all the moles by the smallest number of moles. In this case, the smallest number is 0.75.
C: 0.75 mol / 0.75 mol = 1
H: 1.5 mol / 0.75 mol = 2
O: (60 g / (molar mass of O) - 0.75 mol - 1.5 mol) / 0.75 mol
Simplifying the ratio:
C: 1
H: 2
O: (60 g - 0.75 g - 1.5 g) / (molar mass of O * 0.75 g/mol)
3. Determine the empirical formula:
The empirical formula is the simplest whole number ratio for each element. In this case, it is CH2O.
4. Calculate the molecular formula:
To find the molecular formula, we need to divide the relative molecular mass (60 g/mol) by the empirical formula's molar mass.
Molar mass of CH2O = (12 g/mol * 1) + (1 g/mol * 2) + (16 g/mol * 1) = 30 g/mol
Divide the relative molecular mass (60 g/mol) by the empirical formula molar mass (30 g/mol).
Molecular formula = (relative molecular mass) / (empirical formula molar mass)
Molecular formula = 60 g/mol / 30 g/mol = 2
The molecular formula is then (CH2O)2, which simplifies to C2H4O2.