An unknown compound contans only C, H, and O. Combustion of 5.70 g of this compound produced 11.4g of CO2 and 4.66g of H2O. What is the empirical formula of the unknown compound?
CHO
Are you asking if CHO is correct. No it isn't.
Convert 11.4 g CO2 to grams C.
Convert 4.55 g H2O to grams H2.
Add the two and subtract from 5.70 g to find grams oxygen.
Then convert g C to moles. moles = grams/molar mass
Convert g hydrogen to moles (H atoms) = /
Convert g oxygen to moles O.
Then find the ratio of each with the smallest being 1.00. The easy way to do that is to divide the smallest value by itself (thereby assuring 1.00 for that element), then divide the other numbers by the same small value. Round to whole numbers.
Post your work if you get stuck.
To determine the empirical formula of the unknown compound, we need to find the ratio of carbon (C), hydrogen (H), and oxygen (O) atoms present in the compound.
First, let's find the moles of CO2 and H2O produced during combustion:
1. Moles of CO2: Using the molar mass of CO2 (44.01 g/mol), we can calculate the moles as follows:
moles of CO2 = mass of CO2 / molar mass of CO2
moles of CO2 = 11.4 g / 44.01 g/mol
moles of CO2 ≈ 0.2597 mol
2. Moles of H2O: Using the molar mass of H2O (18.015 g/mol), we can calculate the moles as follows:
moles of H2O = mass of H2O / molar mass of H2O
moles of H2O = 4.66 g / 18.015 g/mol
moles of H2O ≈ 0.2585 mol
Next, let's find the moles of carbon (C), hydrogen (H), and oxygen (O) in the unknown compound:
3. Moles of C: From the balanced combustion equation, we know that for each mole of CO2 produced, there is one mole of carbon (C) present. Therefore, the number of moles of C is the same as the moles of CO2, which is approximately 0.2597 mol.
4. Moles of H: From the balanced combustion equation, we know that for each mole of H2O produced, there are two moles of hydrogen (H) present. Therefore, the number of moles of H is twice the moles of H2O, which is approximately 2 * 0.2585 mol = 0.517 mol.
5. Moles of O: To find the moles of oxygen (O), we need to subtract the total moles of C and H from the total moles of the compound, which is equal to the sum of the moles of CO2 and H2O:
moles of O = moles of CO2 + moles of H2O - moles of C - moles of H
moles of O = 0.2597 + 0.2585 - 0.2597 - 0.517
moles of O ≈ -0.2597 mol
Since we cannot have a negative number of moles, this negative value suggests that there was an error in the calculations.
Taking into account the limiting reactant (the reactant that is completely consumed in a chemical reaction), we can see that the moles of H2O (0.2585 mol) are slightly less than the moles of CO2 (0.2597 mol). Hence, we can use the moles of H2O as the limiting reagent.
Now, let's round the number of moles of carbon (C), hydrogen (H), and oxygen (O) to the nearest whole number:
C ≈ 0.2597 mol ≈ 0 moles (rounded to 0)
H ≈ 2 * 0.2585 mol ≈ 0.517 mol ≈ 1 mole (rounded to 1)
O ≈ -0.2597 mol (error in calculation, disregard)
The empirical formula of the unknown compound is therefore CHO, indicating that it contains one carbon (C), one hydrogen (H), and one oxygen (O) atom.