on complete combustion of one mole of a certain alkane , two moles of C02 and three moles of water was produced. determine the relative molecular formula of the compound.
(C= 1, O=16)
You will need molecular weight value of the compound under-going combustion to complete the problem objective. With the data given, only the empirical formula can be found.
To determine the relative molecular formula of the compound from the products of its combustion reaction, we need to calculate the empirical formula first. The empirical formula shows the simplest whole number ratio of atoms in a compound.
In this case, we know that one mole of the alkane produces two moles of CO2 and three moles of water. Let's start by calculating the moles of carbon and oxygen from CO2 and hydrogen and oxygen from H2O.
1 mole of CO2 contains 1 mole of carbon and 2 moles of oxygen.
Therefore, 2 moles of CO2 contain 2 moles of carbon and 4 moles of oxygen.
3 moles of H2O contain 6 moles of hydrogen and 3 moles of oxygen.
Now, let's compare the moles of carbon and hydrogen in the alkane to see if they have a common factor.
Since two moles of CO2 are produced from one mole of the alkane, it means that the alkane contains 1 mole of carbon.
And since three moles of H2O are produced from one mole of the alkane, it means that the alkane contains 6 moles of hydrogen.
The ratio of carbon to hydrogen is 1:6.
Now, let's find the empirical formula by dividing the subscripts by their greatest common divisor:
Carbon: 1 ÷ 1 = 1
Hydrogen: 6 ÷ 1 = 6
So, the empirical formula of the compound is CH6.
To find the relative molecular formula, we need to determine the molecular mass of the compound and compare it to the empirical formula.
The molecular mass of CH6 is:
(1 × 12.01) + (6 × 1.008) = 18.06 g/mol
Comparing the molecular mass to the empirical formula mass:
Empirical formula mass = (1 × 12.01) + (6 × 1.008) = 18.06 g/mol
Molecular mass = 18.06 g/mol
The molecular mass is the same as the empirical formula mass, which means the empirical formula is the same as the molecular formula.
Therefore, the relative molecular formula of the compound is CH6.