a 2.500g sample of an unknown compound containing only C, H and O was burned in O2. The products were 4.776g of CO2 and 2.934g of H2O.
a) what is the percent compostion of the original compound?
%C-
%H-
%O
and what is empirical formual of compound?
c2h6o
To find the percent composition of the original compound and the empirical formula, we can use the given information about the masses of CO2 and H2O produced.
a) Percent composition of the original compound:
To calculate the percent composition, we'll divide the mass of each element by the total mass of the unknown compound and multiply by 100.
1. Calculate the mass of carbon (C) in the CO2:
Mass of CO2 = 4.776 g
Since 1 mole of CO2 contains 1 mole of carbon, we need to convert the mass of CO2 to the molar mass of carbon.
Molar mass of CO2 = 44.01 g/mol (12.01 g/mol for carbon plus 32.00 g/mol for each oxygen)
Moles of CO2 = Mass of CO2 / Molar mass of CO2 = 4.776 g / 44.01 g/mol
Moles of C = Moles of CO2 (since 1 mole of CO2 contains 1 mole of carbon)
2. Calculate the mass of hydrogen (H) in the H2O:
Mass of H2O = 2.934 g
Since 1 mole of H2O contains 2 moles of hydrogen, we need to convert the mass of H2O to the molar mass of hydrogen.
Molar mass of H2O = 18.02 g/mol (2.01 g/mol for hydrogen plus 16.00 g/mol for oxygen)
Moles of H2O = Mass of H2O / Molar mass of H2O = 2.934 g / 18.02 g/mol
Moles of H = 2 * Moles of H2O (since 1 mole of H2O contains 2 moles of hydrogen)
3. Calculate the mass of oxygen (O) in the CO2 and H2O:
Mass of oxygen (O) = Total mass of the unknown compound - Mass of C - Mass of H
Mass of C = Moles of C * Molar mass of C
Mass of H = Moles of H * Molar mass of H
4. Calculate the percent composition of each element:
%C = (Mass of C / Total mass of the unknown compound) * 100
%H = (Mass of H / Total mass of the unknown compound) * 100
%O = (Mass of O / Total mass of the unknown compound) * 100
b) Empirical formula of the compound:
The empirical formula represents the simplest whole number ratio of the elements present in a compound. To determine the empirical formula, we can use the moles of each element obtained in step 1 and 2.
1. Find the simplest ratio of moles of C, H, and O by dividing each by the smallest number of moles.
2. Round the moles to the nearest whole number.
3. Write the empirical formula using these whole numbers.
To determine the percent composition of the original compound, you need to calculate the mass of each element (C, H, and O) in the sample and then divide it by the total mass of the sample. Here are the steps:
1. Calculate the mass of carbon (C):
We know that the products of combustion are 4.776g of CO2. The molar mass of CO2 is 44.01 g/mol, and since each molecule of CO2 contains one carbon atom, the molar mass of carbon alone is 12.01 g/mol.
Using the given mass of CO2:
Mass of C = mass of CO2 × (mass of C/molar mass of CO2)
Mass of C = 4.776g × (12.01g/mol ÷ 44.01g/mol)
2. Calculate the mass of hydrogen (H):
We know that the products of combustion are 2.934g of H2O. The molar mass of H2O is 18.02 g/mol, and since each molecule of H2O contains two hydrogen atoms, the molar mass of hydrogen alone is 2.02 g/mol.
Using the given mass of H2O:
Mass of H = mass of H2O × (2 × mass of H/molar mass of H2O)
Mass of H = 2.934g × (2 × 2.02g/mol ÷ 18.02g/mol)
3. Calculate the mass of oxygen (O):
We can subtract the mass of carbon and hydrogen from the total sample mass to find the mass of oxygen.
Mass of O = total sample mass - (mass of C + mass of H)
4. Calculate the percent composition of each element:
% Composition of C = (mass of C / total sample mass) × 100
% Composition of H = (mass of H / total sample mass) × 100
% Composition of O = (mass of O / total sample mass) × 100
To find the empirical formula of the compound, you need the molar ratios between the elements. To determine this, divide the number of moles for each element by the smallest number of moles calculated. This will give you the simplest whole-number ratio, which represents the empirical formula.
Let me know if you'd like me to calculate the percent composition and empirical formula for you based on the given numbers!