To find the percent by mass of each element in phosphine (PH3), you can follow these steps:
Determine the molar masses of the elements involved:
Phosphorus (P) has a molar mass of approximately 30.97 g/mol.
Hydrogen (H) has a molar mass of approximately 1.01 g/mol.
Calculate the molar mass of phosphine (PH3):
PH3 consists of one phosphorus atom and three hydrogen atoms.
Molar mass of PH3 = (1 * molar mass of P) + (3 * molar mass of H)
Molar mass of PH3 = (1 * 30.97 g/mol) + (3 * 1.01 g/mol) = 34.00 g/mol
Determine the mass of each element in 129.9 g of phosphine:
Mass of phosphorus (P) in 129.9 g of PH3 = (1 * 30.97 g/mol) = 30.97 g
Mass of hydrogen (H) in 129.9 g of PH3 = (3 * 1.01 g/mol) = 3.03 g
Calculate the percent by mass of each element:
Percent by mass of phosphorus (P) = (Mass of P / Total mass of PH3) * 100%
Percent by mass of P = (30.97 g / 129.9 g) * 100% ≈ 23.85%
Percent by mass of hydrogen (H) = (Mass of H / Total mass of PH3) * 100%
Percent by mass of H = (3.03 g / 129.9 g) * 100% ≈ 2.33%
So, the percent by mass of phosphorus in phosphine (PH3) is approximately 23.85%, and the percent by mass of hydrogen is approximately 2.33%.