To calculate the molar mass of a compound, you need to find the atomic masses of each element in the compound and then multiply them by the respective subscripts.
The atomic mass of arsenic (As) is approximately 74.92 g/mol, and the atomic mass of selenium (Se) is approximately 78.96 g/mol.
For As2Se5, we have:
2 atoms of As: 2 x 74.92 g/mol = 149.84 g/mol 5 atoms of Se: 5 x 78.96 g/mol = 394.80 g/mol
Adding these values together gives us the molar mass of As2Se5:
149.84 g/mol + 394.80 g/mol = 544.64 g/mol
Therefore, the molar mass of As2Se5 is approximately 544.64 g/mol.