To calculate the molar mass of barium nitrate Ba NO3 2 , we need to find the molar mass of each element in the compound and then add them together.1. Barium Ba : The molar mass of barium is 137.33 g/mol.2. Nitrogen N : The molar mass of nitrogen is 14.01 g/mol. Since there are two nitrogen atoms in each nitrate ion NO3- and two nitrate ions in the compound, there are a total of 4 nitrogen atoms. So, the total molar mass of nitrogen in the compound is 4 14.01 g/mol = 56.04 g/mol.3. Oxygen O : The molar mass of oxygen is 16.00 g/mol. There are three oxygen atoms in each nitrate ion NO3- and two nitrate ions in the compound, making a total of 6 oxygen atoms. So, the total molar mass of oxygen in the compound is 6 16.00 g/mol = 96.00 g/mol.Now, we add the molar masses of all the elements in the compound:Molar mass of Ba NO3 2 = Molar mass of Ba + Molar mass of N + Molar mass of OMolar mass of Ba NO3 2 = 137.33 g/mol + 56.04 g/mol + 96.00 g/molMolar mass of Ba NO3 2 = 289.37 g/molSo, the molar mass of barium nitrate Ba NO3 2 is 289.37 g/mol.