Final answer:
The mass percentage of carbon in a sample of pure serine, molecular formula C3H7NO3, is calculated to be 34.29% by dividing the total mass of carbon (36.03 g/mol) by the molecular weight of serine (105.09 g/mol) and multiplying by 100.
Step-by-step explanation:
Calculating the mass percentage of carbon in serine, an amino acid with the molecular formula C₃H₇NO₃, involves determining the total mass of carbon in the molecule compared to the total molecular mass. The molecular weight of serine is 105.09 g/mol, which includes 3 carbon atoms each with an atomic mass of approximately 12.01 g/mol. So, the total mass of carbon is 3 x 12.01 g/mol = 36.03 g/mol.
To find the mass percentage, divide the total mass of carbon by the molecular weight of serine and multiply by 100:
Mass percentage of carbon = (Total mass of carbon / Molecular weight of serine) x 100 = (36.03 g/mol / 105.09 g/mol) x 100 = 34.29%
Thus, serine contains 34.29% carbon by mass.