You take an aspirin tablet (a compound consisting solely of carbon,hydrogen,and oxygen)with a mass of 1.00 g,burn it in air,and collect 2.20 g of carbon dioxide and 0.400 g water.The molar mass of aspirin is between 170 and 190 g/mol.The molecular formula of aspirin is

Question

Quizplus · Accepted Answer

First, we need to find the number of moles of carbon dioxide and water produced in the combustion of 1.00 g of aspirin.

moles of CO2 = (2.20 g)/(44.01 g/mol) = 0.050 mol
moles of H2O = (0.400 g)/(18.02 g/mol) = 0.022 mol

Next, we need to find the empirical formula of aspirin. We can assume that all the carbon, hydrogen, and oxygen in the aspirin molecule is converted to CO2 and H2O.

From the balanced chemical equation for the combustion:

C9H8O4 + 9O2 -> 9CO2 + 4H2O

We can see that 9 moles of CO2 are produced for every mole of C9H8O4. Therefore, the empirical formula for aspirin can be calculated as:

C: (9 mol CO2) / (0.050 mol) = 180
H: (4 mol H2O) / (0.022 mol) = 182 
O: (9*2 + 4) = 22

Dividing all by the smallest subscript, we get the empirical formula as C9H8O4.

Finally, we need to find the molecular formula of the aspirin.

Molar mass of empirical formula: 
(9*12.01 g/mol) + (8*1.01 g/mol) + (4*16.00 g/mol) = 180.16 g/mol

Dividing the molar mass of the aspirin given in the question (between 170 and 190 g/mol) by the molar mass of the empirical formula gives a range of 0.94 to 1.05.

Therefore, the molecular formula of aspirin can be written as (C9H8O4)n, where n is between 0.94 and 1.05. The only answer choice that fits this requirement is B, which has a molecular formula of C9H8O4.

You Take an Aspirin Tablet (A Compound Consisting Solely of Carbon,hydrogen,and