Question

In the second footnote it was pointed out that mass and energy are alternate aspects of a single entity called mass-energy. The relationship between these two physical quantities is Einstein's equation, E= mc^2, where E is energy, m is mass, and c is the speed of light. In a combustion experiment, it was found that 12.096 g of hydrogen molecules combined with 96.000 g of oxygen molecules to form water and released 1.715 x 10^3 kJ of heat. Use Einstein's equation to calculate the corresponding mass change in this process, and comment on whether or not the law of conservation of mass holds for ordinary chemical processes.

Answer 1

Answer:

The corresponding mass change in this process is $1.9055\times 10^{-8} g$

Explanation:

$E= mc^2$,

where :

E is energy released with respect to mass

m is change mass

c is the speed of light.

2.096 g of hydrogen molecules combined with 96.000 g of oxygen molecules to form water and released energy E.

$E=1.715\times 10^3 kJ=1.715\times 10^6 J$

Mass change in this process = m

$1.715\times 10^6 J=m\times (3\times 10^8 m/s)^2$

$m=1.9055\times 10^{-11} kg=1.9055\times 10^{-8} g$

The change in mass calculated from Einstein equation is small that its effect on formation of product will be negligible.Hence, law of conservation of mass holds correct for chemical reactions.