To find the mass of 3.81 moles of PH3 (phosphine), we first need to know the molar mass of PH3.
The molar mass is calculated by adding the atomic masses of phosphorus (P) and hydrogen (H). The atomic mass of phosphorus is approximately 31.00 g/mol, and that of hydrogen is about 1.01 g/mol. Since there are three hydrogen atoms in PH3, we calculate the molar mass as follows:
Molar mass of PH3 = Atomic mass of P + (3 × Atomic mass of H)
Molar mass of PH3 = 31.00 g/mol + (3 × 1.01 g/mol)
Molar mass of PH3 = 31.00 g/mol + 3.03 g/mol = 34.03 g/mol
Now, we can find the mass of 3.81 moles of PH3 by using the formula:
Mass = Number of moles × Molar mass
Mass = 3.81 moles × 34.03 g/mol
Calculating this gives us:
Mass = 129.79 g
Therefore, the mass of 3.81 moles of PH3 is approximately 129.79 grams.