Barium nitrate, molar mass

Scientists also use the simplest formula to represent one mole of an ionic compound. They often use the term formula unit when referring to ionic compounds, because they are not found as single molecules. A formula unit of an ionic compound represents the simplest ratio of cations to anions. A formula unit of KBr is made up of one ion and one Br ion. One mole of an ionic compound has 6.022 x 10 of these formula units. As with molecular compounds, the molar mass of an ionic compound is the sum of the masses of all the atoms in the formula expressed in g/mol. Table 1 compares the formula units and molar masses of three ionic compounds. Sample Problem F shows how to calculate the molar mass of barium nitrate. 

Sample Problem G What is the molar mass of barium nitrate, Ba(N03)2 ... 

One mole of barium nitrate contains exactly one mole of Ba2+ ions and two moles ofNOJ ions. The two moles ofNOJ ions contain two moles of N atoms and six moles of O atoms. Therefore, the molar mass of Ba(N03)2 is calculated as follows. 

At the equivalence point, the indicator turns red. The standard solutions contain either barium nitrate or sodium or ammonium sulfate. In both cases, the equivalent is half the molar mass. These titrations are rarely performed because the detection of their equivalence point is unreliable. Most of all, it is used to quickly determine Ba + concentrations. In the presence of barium ions, the indicator is red. After the addition of an excess of sulfate ions, the color disappears ... 

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