Give the number of atoms of the specified element in a formula unit of each of the following compounds, and calculate the molecular (formula) mass: (a) Hydrogen in ammonium benzoate, C6H5COON H4 (b) Nitrogen in hydrazinium sulfate, N2H6804 (c) Oxygen in the mineral leadhillite, Pb4SO4iCO3) 2 (OH) 2

a) C6H5COONH4 = 139.134 f. g. u

b) N2H68O4 = 160.518 f. g. u

c) Pb4SO4 (CO3) 2 (OH) 2 = 1078.777 f. g. u

Explanation:

the formula of a compound gives the relative number of atoms of each element present, represents what is called a formula unit; to calculate the formula weight (or molecular weight) of a compound. This is done considering the number of atoms of the formula unit of the compound and the atomic weights of the elements.

a) C6H5COONH4:

⇒ C : (6 * (12.0107)) + (1 * (12.0107)) = 84.0749 f. g C

⇒ H : (5 * 1,008) + (4 * 1.008) = 9.072 f. g H

⇒ N : 1 * 14.007 = 14.007 f. g N

⇒ O : 2 * 15.99 = 31.98 f. g O

f. w C6H5COONH4 = 84.0749 + 9.072 + 14.007 + 31.98 = 139.134 f, g

b) N2H68O4:

⇒ N : 2 * 14.007 = 28.014 f. g N

⇒ H : 68 * 1.008 = 68.544 f. g H

⇒ O : 4 * 15.99 = 63.96 f. g O

f. w N2H68O4 = 28.014 + 68.544 + 63.96 = 160.518 f. g

c) Pb4SO4 (CO3) 2 (OH) 2:

⇒ Pb : 4 * 207.2 = 828.8 f. g Pb

⇒ S : 1 * 32.06 = 32.06 f. g S

⇒ O : (4 * 15.99) + (6 * 15.99) + (2 * 15.99) = 191.88 f. g O

⇒ C : 2 * 12.0107 = 24.0214 f. g C

⇒ H : 2 * 1.008 = 2.016 f. g H

f. w Pb4SO4 (CO3) 2 (OH) 2 = 828.8 + 32.06 + 191.88 + 24.0214 + 2.016 = 1078.777 f. g