1. Explain how the Law of conservation of mass is applied in the situation below.
5.2 g of CaCO3 when heated produced 2.0 g of carbon dioxide and the residue (CaO) left behind weighs 3.2g.
2. Explain how the Law of multiple proportions is applied in the situation below.
Carbon is found to form two oxides, which contain 42.9% and 27.3% of carbon respectively
3. Explain how the Law of definite composition is applied in the situation below.
Irrespective of the source, a pure sample of water always yields 88.89% mass of oxygen
and 11.11% mass of hydrogen.
Answers
Answer:
1. This law states that, despite chemical reactions or physical transformations, mass is conserved — that is, it cannot be created or destroyed — within an isolated system. In other words, in a chemical reaction, the mass of the products will always be equal to the mass of the reactants.
2. It states that the masses of one element which combine with fixed mass of second element are in a ration of whole number therefore the masses of oxygen in the two compounds that combine with fixed mass of carbon should be in a whole number ration 100 gram of first compound contains 42.9% of carbon and 57.1% oxygen.
so 42.9 gram of carbon and 57.1 gram of oxygen
the mass of oxygen per gram of carbon is
42.9
57.1
=1.33gram O per gram c
the 100 gram of second compound there are 72.7 gram of O and 27.3 gram of C
the mass of oxygen per gram of carbon is
27.3
72.7
=2.66 gram O per gram C
The mass fraction =
1.33
2.66
=2:1
the whole number ratio is consistent with the law of multiple.
3. This law states that "in a chemical substance, the elements are always present in definite proportions by mass".
For example:
In water H
2
O, hydrogen and oxygen are always present in the ratio of 1:8 by mass, whatever the method or source from which water is obtained.
Massof 2 hydrogen atom=2
Mass of one oxygen atom=16
Hence, ratio of hydrogen and oxygen by mass=2:16=1:8