Prior to their phaseout in the 1980s, chemicals containing lead were commonly added to gasoline as anti-knocking agents. A 3.279 g sample of one such additive containing only lead, carbon, and hydrogen was burned in an oxygen rich environment. The products of the combustion were 3.569 g of CO2(g) and 1.826 g of H2O(g). Insert subscripts below to appropriately display the empirical formula of the gasoline additive:
I got C2H5 but I do not know how to get the empirical formula for CHPb
I worked this for you a day or so ago. Find that and you have it. Or post your work here and I can show you where you're going wrong.
To determine the empirical formula of the gasoline additive, you need to calculate the number of moles of carbon, hydrogen, and lead present in the given weights of CO2, H2O, and the gasoline additive.
1. Start by calculating the number of moles of CO2 formed:
- The molar mass of CO2 is 44.01 g/mol.
- Divide the mass of CO2 (3.569 g) by its molar mass to find the number of moles of CO2.
Example calculation:
Moles of CO2 = 3.569 g / 44.01 g/mol = 0.0811 mol
2. Calculate the number of moles of H2O:
- The molar mass of H2O is 18.015 g/mol.
- Divide the mass of H2O (1.826 g) by its molar mass to find the number of moles of H2O.
Example calculation:
Moles of H2O = 1.826 g / 18.015 g/mol = 0.1013 mol
3. Next, calculate the moles of carbon and hydrogen present in the gasoline additive:
- The initial mass of the gasoline additive is 3.279 g.
- Subtract the masses of CO2 and H2O from the initial mass to find the mass of the remaining elements (C and H).
- Divide the mass of carbon by the molar mass of carbon (12.01 g/mol) to find the number of moles of carbon.
- Divide the mass of hydrogen by the molar mass of hydrogen (1.01 g/mol) to find the number of moles of hydrogen.
Example calculation:
Mass of carbon = (3.279 g - mass of CO2) = (3.279 g - 3.569 g) = -0.290 g
Moles of carbon = -0.290 g / 12.01 g/mol = -0.0241 mol (rounded to 3 significant figures)
Mass of hydrogen = (3.279 g - mass of H2O) = (3.279 g - 1.826 g) = 1.453 g
Moles of hydrogen = 1.453 g / 1.01 g/mol = 1.44 mol (rounded to 3 significant figures)
4. Finally, determine the empirical formula of the gasoline additive by dividing each number of moles by the smallest number of moles, and then adjusting the subscripts to the nearest whole numbers.
Example empirical formula calculation:
The smallest number of moles is 0.0241 mol.
Divide the number of moles of each element by 0.0241 mol:
Carbon: 0.0241 mol / 0.0241 mol = 1
Hydrogen: 1.44 mol / 0.0241 mol = 59.8
Lead: Since there is only lead in the additive, the number of moles is 1 (approximated from 3 significant figures).
Adjust the subscripts to whole numbers:
The empirical formula is C1H60Pb.
Therefore, the empirical formula of the gasoline additive is C1H60Pb.