Empirical Formula - Online
To determine the empirical formula of a compound by use of a combination reaction.
To practice techniques for obtaining and recording precise mass values.
To learn safe practices of Bunsen burner use.
The empirical formula of a compound is the simplest (smallest) whole-number ratio of moles of elements in the
compound. Determination of the empirical formula requires three steps:
Obtain the actual mass of each element in the compound
Calculate the moles of each element from its actual mass and molar mass
Express the ratio of moles of each element as small whole numbers
Elemental analysis of a sample of an unknown crystalline solid reveals the presence of 5.52 g of sodium and 8.48
g of chlorine as the only components. The moles of each element are calculated:
Moles of sodium:
g Na x
Moles of chlorine:
The mole ratio of sodium to chlorine in the compound is 0.240 : 0.239. Expressing the mole ratio as the simplest
whole-number mole ratio reveals 1 mol Na : 1 mol Cl. The empirical formula is
, and the compound is
The empirical formula of a
can be determined by carrying out a
temperature in air. The mass of the metal before the reaction, and the total mass of the metal oxide after the reaction
From the difference between the masses, the mass of oxygen in the metal oxide is determined. The
moles of each element are calculated and the mole ratio of the two elements yields the empirical formula for the metal
A 5.90 g sample of titanium metal combines with oxygen in the air to form 9.84 g of titanium oxide.
empirical formula of the titanium oxide can be determined as follows:
Moles of titanium:
Mass of oxygen: 9.84 g compound – 5.90 g Ti = 3.94 g O
Moles of oxygen:
Empirical Formula Fall18