A student heats 2.796 g of zinc powder with 2.414 g of sulfur. He reports that he obtains 4.169 g of zinc sulfide and recovers 1.041 g of unreacted sulfur. Show by calculation whether or not his results obey the law of conservation of mass. Essay answers are limited to about 500 words
The law of conservation of mass states that in chemical reactions different elements can be combined to form different compounds, or converted from one compound to another or compounds broken to individual elements but it is not possible to change the total mass of the chemical elements being used. The total initial mass of the reactants is equal to the total final mass of the products.
When the student heats 2.796 g of zinc powder with 2.414 g of sulfur he reports that 4.169 g of zinc sulfide is obtained with 1.041 g of sulfur.
The total mass of the reactants is 2.796 + 2.414 = 5.21 g. The total mass of the products is 4.169 + 1.041 = 5.21 g.
It is seen that the mass of the reactants and that of the products is equal. This shows the law of conservation of mass is being followed.
Total mass before reaction = 2.796+2.414 = 5.21g
Total mass after reaction = 4.169+1.041 = 5.21g
Hence, law of conservation of mass is obeyed.
The law of conservation of mass states that mass is not created or destroyed, only transformed. Before the reaction, the student had a total mass of 5.21 g of zinc and sulfur. After it is heated, they received 4.169 g of zinc sulfide and 1.041 g of sulfur. When added the mass still equals 5.21 g meaning that no mass was created or destroyed after the reaction and the law of conservation of mass was obeyed.