What are the molecular weights of the following compounds? (all masses must be to nearest hu 1) NaOH 3) H_(2)O 5) MgCl_(2) 2) H_(3)PO_(4) 4) Mn_(2)Se_(7) 6) (NH_(4))_(2)SO_(4)

To calculate the molecular weights of the given compounds, we need to sum the atomic masses of each element in the compound, taking into account the number of atoms of each element present.<br /><br />1) NaOH:<br />- Sodium (Na): 22.99 g/mol<br />- Oxygen (O): 16.00 g/mol<br />- Hydrogen (H): 1.01 g/mol<br /><br />Molecular weight of NaOH = 22.99 + 16.00 + 1.01 = 40.00 g/mol<br /><br />2) H3PO4:<br />- Hydrogen (H): 1.01 g/mol (3 atoms)<br />- Phosphorus (P): 30.97 g/mol<br />- Oxygen (O): 16.00 g/mol (4 atoms)<br /><br />Molecular weight of H3PO4 = 3(1.01) + 30.97 + 4(16.00) = 97.99 g/mol<br /><br />3) H2O:<br />- Hydrogen (H): 1.01 g/mol (2 atoms)<br />- Oxygen (O): 16.00 g/mol<br /><br />Molecular weight of H2O = 2(1.01) + 16.00 = 18.02 g/mol<br /><br />4) Mn2Se7:<br />- Manganese (Mn): 54.94 g/mol (2 atoms)<br />- Selenium (Se): 78.96 g/mol (7 atoms)<br /><br />Molecular weight of Mn2Se7 = 2(54.94) + 7(78.96) = 744.72 g/mol<br /><br />5) MgCl2:<br />- Magnesium (Mg): 24.31 g/mol<br />- Chlorine (Cl): 35.45 g/mol (2 atoms)<br /><br />Molecular weight of MgCl2 = 24.31 + 2(35.45) = 95.21 g/mol<br /><br />6) (NH4)2SO4:<br />- Nitrogen (N): 14.01 g/mol (2 atoms)<br />- Hydrogen (H): 1.01 g/mol (8 atoms)<br />- Sulfur (S): 32.07 g/mol<br />- Oxygen (O): 16.00 g/mol (4 atoms)<br /><br />Molecular weight of (NH4)2SO4 = 2(14.01) + 8(1.01) + 32.07 + 4(16.00) = 132.14 g/mol