Purpose:
The purpose of this experiment is to determine the chemical formula. Here the chemical formula will be determined from the oxide of the metal. The metal is to be identified from the given mass.
Calculation:
Mass of crucible, lid and metal are given to be 38.834 gram whereas the mass of crucial and lid are 37.933 gram and 37.938 gram respectively. Hence it can be said that the constant mass of crucible and lid is 37.936 gram. Hence, the mass of the metal which is used can calculated as
(38.834 - 37.936) gram=0.898 gram.
After the first heating the mass of crucible, lid and the product is found to be 39.224 gram whereas after the second heating the mass of those products is found to be 39.227 gram. Hence, it can be calculated that the constant mass of crucible, lid and the product is 39.226 gram.
Now the mass of the oxygen in the compound = (39.226 - 38.834) =0.392 gram.
Molar mass of the metal is given to be 55.8 gram/mol
Hence the relative number of moles of the metal in the compound can be calculated as follows:
0.898/55.8=0.0161 mole
Similarly the relative number of moles of oxygen in the compound can be calculated and it is given below:
0.392/16.0=0.0245 mole
Simple ratio of moles of metal and the oxygen can be calculated as below:
Metal = 0.0161/0.0161=1; oxygen = 0.0245/0.0161=1.52
Multiplying by 2, the following can be written
Metal=2 and Oxygen=3.04.
Hence the integral ratio of moles of metal to oxygen=2:3
Hence the formula of the compound is determined to be Fe2O3 [as molar mass of Fe is 55.8 gram/mole]
Conclusion:
This law states that all the elements in a compound are always combined in the equal proportion by their mass. From this law the definition of chemical compound can be formed.
When magnesium is burnt in air, there are two products that are formed. One is known as magnesium oxide and the other is known to be magnesium nitride. The main purpose of adding water into the magnesium nitride is to produce ammonia gas and magnesium oxide.
If white smoke is escaped, it will change the mass of the product and as a result it will be hard to find the exact empirical formula.
Chemical formulas:
Magnesium nitride=Mg3N2
Water=H2O
Magnesium hydroxide=Mg(OH)2
Ammonia=NH3
Oxygen=O2
Nitrogen=N2
