Question

determine the percent composition of salicylic acid, c₇h₆o₃? the molar mass of c₇h₆o₃ is 138.1 g/mol.
o 60.88% c, 4.379% h, 34.76% o
o 52.34% c, 5.762% h, 41.89% o
↑o 50.72% c, 4.426% h, 44.85% o
o 65.34% c, 6.271% h, 28.39% o
o 62.81% c, 3.274% h, 33.92% o

Explanation:

Step1: Calculate mass of carbon

The atomic mass of C is approximately 12.01 g/mol. In $C_7H_6O_3$, there are 7 C atoms. So the mass contributed by C is $7\times12.01 = 84.07$ g/mol. The percent - mass of C is $\frac{84.07}{138.1}\times100\%\approx60.88\%$.

Step2: Calculate mass of hydrogen

The atomic mass of H is approximately 1.01 g/mol. In $C_7H_6O_3$, there are 6 H atoms. So the mass contributed by H is $6\times1.01 = 6.06$ g/mol. The percent - mass of H is $\frac{6.06}{138.1}\times100\%\approx4.39\%$ (close to 4.379%).

Step3: Calculate mass of oxygen

The atomic mass of O is approximately 16.00 g/mol. In $C_7H_6O_3$, there are 3 O atoms. So the mass contributed by O is $3\times16.00 = 48$ g/mol. The percent - mass of O is $\frac{48}{138.1}\times100\%\approx34.76\%$.

Answer:

60.88% C, 4.379% H, 34.76% O