In: Chemistry
a statement of the first law of thermodynamics is that a. in a spontaneous process, the entropy of the universe increases b. there is no disorder in a perfect crystal at 0 k. c. the total energy of the universe is constant. d. the totla energy of the universe is constant. e. mass and energy are conserved in all chemical reactions
Answer : According to first law of thermodynamics, the total energy of universe is constant.
Reason :it is commonly observed that energy can't be generated without using energy of some other kind .whenever the energy of one kind is produced, an equal amount of some other kind of energy disappears so that the total energy of universe is constant.
Option a) is incorrect because it is a statement of second law of thermodynamics.
Option b) is incorrect because it is a statement of third law of thermodynamics.
Option e) is incorrect. In chemical reactions, mass is conserved which is called law of conservation of mass. However, mass and energy are conserved in nuclear reactions because nuclei is involved in nuclear reactions. Mass lost by nuclei is converted into energy according to Einstein equation E=mc2.In chemical reactions, nuclei remain unaffected so this equation doesn't carry importance in chemical thermodynamics.
Option c and d are same. Both options are correct.