To determine the empirical formula, we need to find the ratios of the elements in the compound.
Given:
%C = 3.99%
%H = 6.7%
%O = 53.4%
Convert the percentages to grams:
%C: 3.99 g
%H: 6.7 g
%O: 53.4 g
Next, we need to convert the grams of each element to moles.
Convert grams of carbon to moles:
C: 3.99 g
Molar mass of carbon (C): 12.01 g/mol
Moles of carbon = grams of carbon / molar mass of carbon
Moles of carbon = 3.99 g / 12.01 g/mol = 0.3322 mol
Convert grams of hydrogen to moles:
H: 6.7 g
Molar mass of hydrogen (H): 1.01 g/mol
Moles of hydrogen = grams of hydrogen / molar mass of hydrogen
Moles of hydrogen = 6.7 g / 1.01 g/mol = 6.6327 mol
Convert grams of oxygen to moles:
O: 53.4 g
Molar mass of oxygen (O): 16.00 g/mol
Moles of oxygen = grams of oxygen / molar mass of oxygen
Moles of oxygen = 53.4 g / 16.00 g/mol = 3.3375 mol
Now, divide each mole value by the smallest mole value to find the simplest whole number ratio.
Smallest mole value = 0.3322 mol (carbon)
C: 0.3322 mol / 0.3322 mol = 1
H: 6.6327 mol / 0.3322 mol = 19.928 (approximately 20)
O: 3.3375 mol / 0.3322 mol = 10.05 (approximately 10)
The empirical formula is therefore CH2O.
To determine the molecular formula, we need to know the molar mass of the compound.
Given: Molecular mass of the compound = 60 g/mol
Calculate the empirical formula mass:
C: 12.01 g/mol * 1 atom = 12.01 g/mol
H: 1.01 g/mol * 2 atoms = 2.02 g/mol
O: 16.00 g/mol * 1 atom = 16.00 g/mol
Empirical formula mass = 12.01 g/mol + 2.02 g/mol + 16.00 g/mol = 30.03 g/mol
To find the molecular formula, divide the molecular mass by the empirical formula mass:
Molecular formula mass = 60 g/mol
Empirical formula mass = 30.03 g/mol
Molecular formula mass / Empirical formula mass = 60 g/mol / 30.03 g/mol = 1.998
Round the ratio to the nearest whole number:
1.998 (approximately 2)
The molecular formula is therefore (CH2O)2 or C2H4O2.
The persentage composition of acitic acid is found to be 3.99%C of 6.7%H and 53.4%O and it molecular mass was determined by experiment to be 60
Calculate the emperical formula and molecular formula?
1 answer