0.531g of an ester (responsible for odour of pineapples) produced 1.21g of $C{O}_2$ and 0.492g of $H_{2}O$ on combustion. Its empirical formula is?

To find the empirical formula of the ester, we need to determine the ratio of its constituent elements based on the given combustion data.

First, let's calculate the moles of CO₂ and H₂O produced:

moles of CO2 = 1.21 g / 44.01 g/mol = 0.0275 mol moles of H2O = 0.492 g / 18.015 g/mol = 0.0273 mol

Since the ester contains C, H, and O, we can assume that the mass of O present in the ester is equal to the mass of O in the products of combustion (CO₂ and H₂O).

mass of O in the products of combustion = (2 mol O in CO2 x 16.00 g/mol) + (1 mol O in H₂O x 18.015 g/mol) = 64.01 g/mol + 18.015 g/mol = 82.025 g/mol

mass of O in the ester = 0.531 g - (mass of C + mass of H)

Now we can set up two equations to solve for the ratios of C and H:

0.0275 mol CO₂ = x mol C 0.0273 mol H₂O = y mol H

where x and y are the number of moles of C and H, respectively.

From the first equation, we can calculate the number of moles of C:

x = 0.0275 mol CO₂ x (1 mol C / 1 mol CO₂) = 0.0275 mol C

From the second equation, we can calculate the number of moles of H:

y = 0.0273 mol H₂O x (2 mol H / 1 mol H₂O) = 0.0546 mol H

Now we can calculate the number of moles of O:

moles of O = (0.531 g - mass of C - mass of H) / 16.00 g/mol

Substituting the values of x, y, and moles of O into the equation, we get:

0.0275 mol C = x = 0.0275 mol 0.0546 mol H = y = 0.0546 mol moles of O = 0.0164 mol

To get the empirical formula, we divide each of the mole values by the smallest of the three (0.0164 mol) and round to the nearest whole number:

C: 0.0275 mol / 0.0164 mol = 1.68 ≈ 2 H: 0.0546 mol / 0.0164 mol = 3.33 ≈ 3 O: 0.0164 mol / 0.0164 mol = 1

Therefore, the empirical formula of the ester is C₂H₃O.