What is the empirical formula for menthol when a 0.1005g sample of menthol is combusted, producing 0.28298g of CO2 and 0.1159g of H2O.
Thank you!
Here an outline of the solution. The answers to the answers in each step should have at least four significant figure.
1. Convert the grams of CO2 and H2O to moles
2. Moles of carbon, C, equals the number of moles of CO2. Convert the moles of C to grams of C.
3. Moles of hydrogen, H, equal (1/2)(moles H2O). Convert moles of H to grams of H.
4. To get grams of oxygen, O, subtract the combined mass of C and H from the mass of the sample:
0.1005g - (grams C + grams H)
Convert the grams of oxygen, O to moles.
5. The formula for menthol is CxHyOz
x = moles of C
y = moles of H
z = moles of O
6. Divide x, y, and z by the smallest of the three values. The new set of values are the subscripts for the formula of menthol. With a little rounding off they should be whole numbers. If not, multiplication by a small whole number may produce the set of three subscripts needed.
To determine the empirical formula of menthol, you need to calculate the moles of carbon, hydrogen, and oxygen in the given sample.
First, calculate the moles of CO2 produced:
Mass of CO2 = 0.28298g
Molar mass of CO2 = 44.01 g/mol
Moles of CO2 = Mass of CO2 / Molar mass of CO2
Next, calculate the moles of H2O produced:
Mass of H2O = 0.1159g
Molar mass of H2O = 18.02 g/mol
Moles of H2O = Mass of H2O / Molar mass of H2O
Since the combustion reaction of menthol results in the production of CO2 and H2O, we can infer that the carbon and hydrogen in menthol are responsible for producing these products.
Now, let's calculate the moles of carbon and hydrogen:
Moles of carbon = Moles of CO2
Moles of hydrogen = 2 * Moles of H2O
Since the molecular formula of menthol contains oxygen, we can calculate the moles of oxygen present in the sample by applying the principle of conservation of mass (mass before combustion = mass after combustion) as follows:
Mass of menthol sample = Mass of CO2 produced + Mass of H2O produced + Mass of oxygen in the sample
Rearranging the equation, we get:
Mass of oxygen in the sample = Mass of menthol sample - Mass of CO2 produced - Mass of H2O produced
Substituting the given values, we get:
Mass of oxygen in the sample = 0.1005g - 0.28298g - 0.1159g
Now, calculate the moles of oxygen using the molar mass of oxygen (16.00 g/mol) and the obtained mass of oxygen in the sample.
Finally, divide the moles of each element (carbon, hydrogen, oxygen) by the smallest value among them to get the simplest whole-number ratio. This ratio represents the empirical formula of menthol.
That's how you can determine the empirical formula for menthol using the provided data.