Question

what is the percent composition of aspirin, c₉h₈o₄? (molar mass of c₉h₈o₄ = 180.16 g/mol)
o 50.00 % c, 9.48 % h, 40.52 % o
o 60.00 % c, 4.48 % h 35.52 % o
o 40.00 % c, 4.48 % h, 55.52 % o
o 30.00 % c, 4.48 % h, 65.52 % o
o 60.00 % c, 9.48 % h, 30.52 % o

Explanation:

Step1: Calculate mass of carbon

The molar mass of carbon (C) is approximately 12.01 g/mol. In \(C_9H_8O_4\), there are 9 carbon atoms. So the total mass of carbon in one - mole of \(C_9H_8O_4\) is \(9\times12.01 = 108.09\) g. The percent composition of carbon is \(\frac{108.09}{180.16}\times100\%\approx60.00\%\).

Step2: Calculate mass of hydrogen

The molar mass of hydrogen (H) is approximately 1.01 g/mol. In \(C_9H_8O_4\), there are 8 hydrogen atoms. So the total mass of hydrogen in one - mole of \(C_9H_8O_4\) is \(8\times1.01 = 8.08\) g. The percent composition of hydrogen is \(\frac{8.08}{180.16}\times100\%\approx4.48\%\).

Step3: Calculate mass of oxygen

The molar mass of oxygen (O) is approximately 16.00 g/mol. In \(C_9H_8O_4\), there are 4 oxygen atoms. So the total mass of oxygen in one - mole of \(C_9H_8O_4\) is \(4\times16.00 = 64\) g. The percent composition of oxygen is \(\frac{64}{180.16}\times100\%\approx35.52\%\).

Answer:

60.00 % C, 4.48 % H, 35.52 % O