Question

In a certain chemical reaction, there is a decrease in the potential energy (chemical energy) as the reaction proceeds. (a) How does the total kinetic energy of the particles change? (b) How does the temperature of the reaction mixture change?

Answer 1

a) when the potential energy of a system changes, it affects the other forms of energy also. like if potential energy is decreasing, to compensate for the loss, the other forms of energy has to increase so that the overall energy remains constant according to the law of conservation of energy. thus the total kinetic energy of the system will increase when potential energy decreases. potential energy change corresponds to the energy difference between that of reactants to that of products. a loss in potential energy means products are more stable than reactants. and thus the system liberates energy throughout the coordinates which thereby increases the kinetic energy of particles.

b) more the average kinetic energy of particles, more the temperature of that system . An increase in the temperature, increases the speed in which the molecules travels across the coordinates. . All gases at a given temperature have the same average kinetic energy.

E= average kinetic energy of the ideal particle

K= Boltzmann constant

T= absolute temperature

the molecules are not having the same speed, thus energies are distributed according to gaussian behaviour. thus average temperature is taken for measurement.

so when potential energy decreases, kinetic energy increases, products lose their heat, and the system's energy increases.