The empirical formula of a compound can be determined by analyzing the mass percentages of its various elements and expressing them as the smallest whole number ratio. To find the empirical formula of lysine, we first need to determine the number of moles of each element present in 1.50 g of lysine. We can then use these values to calculate the mole ratios of the elements, which will be the same as the ratio of the subscripts in the empirical formula.
By knowing the mass of produced CO2 and H2O we can calculate how many moles of C and H are present in 1.50 g of lysine
mass of C = 2.72 g CO2 x (1 mol CO2 / 44.01 g CO2) = 0.062 moles
moles of H = 1.29 g H2O x (2 moles H / 18.02 g H2O) = 0.072 moles
Then, by knowing that lysine also produced 0.287 g of N. We can calculate the number of moles of N
moles of N = 0.287 g N x (1 mole N / 28.02 g N) = 0.0102 moles
We can now find the ratio of the elements by dividing each by the smallest number of moles which is 0.0102 moles.
C:H:N = 0.062 moles / 0.0102 moles = 6:1:1
So the empirical formula of lysine is C6H14N2
