3.297 g of a substance (containing only C, H, and O) is burned in a combustion analysis apparatus.
The mass of CO2 produced is 3.626 g, and the mass of H2O produced is 9.897×10-1 g.
What is the empirical formula of the compound?
To determine the empirical formula of the compound, we will need to calculate the number of moles of carbon, hydrogen, and oxygen in the given substance. Then, we will divide these moles by the smallest number of moles to get the simplest whole-number ratio of the elements in the compound.
Let's start the calculations:
1. Calculate the number of moles of CO2 produced:
- The molar mass of CO2 is 44.01 g/mol (12.01 g/mol for carbon + 2 * 16.00 g/mol for oxygen).
- Moles of CO2 = mass of CO2 / molar mass of CO2 = 3.626 g / 44.01 g/mol = 0.0825 mol.
2. Calculate the number of moles of H2O produced:
- The molar mass of H2O is 18.02 g/mol (2 * 1.01 g/mol for hydrogen + 16.00 g/mol for oxygen).
- Moles of H2O = mass of H2O / molar mass of H2O = 0.9897 g / 18.02 g/mol = 0.055 mol.
3. Calculate the number of moles of carbon:
- From the balanced equation of combustion:
CxHyOz + (x + y/4 - z/2) O2 → x CO2 + y/2 H2O
- Since the mass of CO2 produced is equal to the moles of carbon in the compound, the moles of carbon are equal to 0.0825 mol.
4. Calculate the number of moles of hydrogen:
- From the balanced equation of combustion:
CxHyOz + (x + y/4 - z/2) O2 → x CO2 + y/2 H2O
- Since the mass of H2O produced is equal to the moles of hydrogen in the compound, the moles of hydrogen are equal to 0.055 mol.
5. Calculate the number of moles of oxygen:
- Moles of oxygen = Moles of CO2 produced - Moles of carbon - Moles of hydrogen
= 0.0825 mol - 0.0825 mol - 0.055 mol
= -0.055 mol (negative value indicates that there is an error)
It appears there is an error in the calculation, as the number of moles of oxygen is negative. This suggests that our assumption regarding the combustion reaction is incorrect or that the given data is inaccurate. Please review the data and equations provided to check for any mistakes or inconsistencies.
If you have any additional information or if you believe there may have been an error, please provide it so that we can assist you further in determining the empirical formula of the compound.
g CO2 = 3.626
g H2O = 0.9897
Plan.
1. Convert g CO2 to g C.
2. Convert g H2O to g H.
3. Find g O in the C,H,O compound from
3.297g total - g C - g H = g O.
mols CO2 = g/molar mass = 0.0842 and that x 12 = 0.9889 g C
g H = 0.9897*2/18 = 0.1099
g O = 2.198
Convert g each to mols.
0.9889/12 = ?
0.1099/1 = ?
2.198/16 = ?
Now find the ratio in whole numbers with the smallest number being 1.00. The easy way to do that is to divide the smallest number by itself and divide the other numbers by the same small number. You will get fractions and not whole numbers. To obtain whole numbers, multiply everything by 2, then 3, then 4, etc until you obtain a set of almost whole numbers, then round to the nearest whole number.
Post your work if you get stuck.