Question: Which of the following is the first law of thermodynamics?
A Energy cannot be created or destroyed
B There is no disorder in a perfect crystal at O K
C In a spontaneous process, the entropy of the universe increases
D The total energy of the universe is always decreasing
E Mass and energy are conserved in all chemical reactions
Answer: Energy cannot be created or destroyed
| Laws of thermodynamics | Equation | Statement |
| Zeroth Law | None | If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other. |
| First Law | ΔU = Q – W | Energy cannot be created or destroyed, only transferred or converted from one form to another form. |
| Second Law | ΔS = Q_rev / T | Heat naturally flows from a hot object to a cold object and work must be done to transfer heat from a cold object to a hot object. |
| Third Law | None | As temperature approaches absolute zero, the entropy of a perfect crystal approaches zero. |