A pencil and paper. Calculations are easier to solve when you write them out. Be sure to show all your steps to get full credit. A periodic table. You will need to be able to find atomic weight of elements using the periodic table. A calculator. Calculators are necessary to simplify calculations of complex numbers.
If a compound is abbreviated with two letters, the first will be capitalized while the second will be lowercase. For example, Mg is the abbreviation for magnesium. The compound NaHCO3 has four elements in it: sodium (Na), hydrogen (H), carbon (C), and oxygen (O).
For example, H2O has two atoms of hydrogen and one atom of oxygen. If a compound has parentheses followed by a subscript, each element within the parentheses gets multiplied by the number in the subscript. For example, (NH4)2S has two atoms of N, eight atoms of H, and one atom of S.
The atomic weight, or mass, or an element is given in atomic mass units (amu). [3] X Research source For example, the molecular weight of oxygen is 15. 99.
Multiply the number of atoms each element contributes to the compound by the atomic weight of that element. Add the total weight of each element in the compound together. For example, (NH4)2S has a molecular weight of (2 x 14.
- (8 x 1.
- (1 x 32.
- = 68. 17 g/mol. Molecular mass is also referred to as molar mass. [6] X Research source
The formula looks like this: moles = grams of compound/molar mass of compound
For example, imagine you have 2 g of (NH4)2S and you want to convert it to moles. The molecular mass of (NH4)2S is 68. 17g/mol. Divide 2 by 68. 17, and you have 0. 0293 moles of (NH4)2S.
