Calculating Formula Weights Calculate the formula weight of (a) sucrose, C12H22O11 (table sugar); and (b) calcium nitrate, Ca(NO3)2. Calculate the formula weight of (a) AI(OH)3, (b) CH3OH, and (c) TaON.
Solution 2PE Formula weight, in chemistry, the sum of the atomic weights of all atoms appearing in a given chemical formula. It is generally applied to a substance that does not consist of individual molecules, such as the ionic compound sodium chloride. Such a substance is customarily represented by a chemical formula that describes the simplest ratio of the number of atoms of the constituent element .e., an empirical formula. Molar mass of 12H22O11(sucrose) is 342.2965 g/mol Formula in Hill system is C12H22O11 Elemental composition of C12H22O11(sucrose): Symbol Element Atomic weight Atoms Mass percent C Carbon 12.0107 12 42.1063 % H Hydrogen 1.00794 22 6.4782 % O Oxygen 15.9994 11 51.4155 %. Step 2 Calcium nitrate The molecular formula of calcium nitrate is Ca(NO3)2. There are three atoms in the molecule 1 calcium,2 nitrogen,and5 oxygen atoms . The atomic weight of calcium is 40.0g . The atomic weight of nitrogen is 14.0g and The atomic weight of oxygen is 16.0g The formula weight of calcium nitrate is 164.9g/mol. Step 3 Formula weight for Al(OH)3 the aluminium hydroxide, Al(OH)3, constitute 1 aluminium atom, 3 oxygen atoms and 3 hydrogen atoms. The formula weight of the molecule can be calculated by adding the atomic weights of all their constituent atoms. Atomic weight of aluminium atom is 27.0 amu. Atomic weight of hydrogen atom is 1.0 amu. Atomic weight of oxygen atom is 16.0 amu. Now, calculate the formula weight for aluminium hydroxide as follows: Weight of 1 atom of aluminium =1(27.0)amu. =27.0amu Weight of 3 atoms of hydrogens =3(1.0)amu =3.0amu. Weight of 3 atoms of oxygen =3(16.0)amu. =48.0amu Now, add weights of all the atoms to calculate the formula weight as follows: Formula weight of Al(OH)3=27.0+3.0+48.0amu =78.0amu. Hence the formula weight of Al(OH)3 is 78.0amu.