Question

State in your own words the law of conservation of mass. State the law in its modern form.

Short answer

Answer: The law of conservation of mass states that in a closed system, the total mass of the substances involved in a chemical reaction remains constant, even if their forms change or the substances rearrange. In its modern form, taking into account the conversion of matter into energy and vice versa, it is expressed as the principle of "conservation of mass-energy," which states that the total mass-energy of a closed system remains constant over time.

Step-by-step solution

Introduction of the law of conservation of mass

The law of conservation of mass, also known as the principle of mass conservation, states that for any closed system (no matter or energy entering or leaving), the mass of the system will remain constant over time. This principle is fundamental in chemistry as it is the basis for balancing chemical equations and understanding chemical reactions.

Writing the law in your own words

To write the law of conservation of mass in your own words, think about what it means and how it applies to various situations. Here is an example of the principle rephrased: "In a closed system, the total mass of the substances involved in a chemical reaction remains the same, even if their forms change or the substances rearrange."

Modern form of the law of conservation of mass

The modern form of the law of conservation of mass takes into account the conversion of matter into energy and vice versa, as described by Einstein's famous equation, E=mc^2, where E represents energy, m represents mass, and c is the speed of light. In its modern form the law may be rephrased as the principle of "conservation of mass-energy," stating that the total mass-energy of a closed system remains constant over time.