Law of Conservation of Mass

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Law of Conservation of Mass Noun

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[law uv kon-ser-vey-shuhn uv mas]

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Law of Conservation of Mass

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The scientific principle stating that mass is neither created nor destroyed during any chemical reaction or physical transformation.

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Example: This diagram shows that the number and type of atoms (the spheres) are the same on the reactant (left) and product (right) sides.

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Physical Change Noun

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[fiz-i-kuhl cheynj]

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Physical Change

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A change affecting the form or state of a chemical substance, but not its fundamental chemical composition or identity.

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Example: This image shows that when 100g of ice cubes melt into liquid water, the mass remains 100g, demonstrating the Law of Conservation of Mass during a physical change.

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Chemical Change Noun

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[kem-i-kuhl cheynj]

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Chemical Change

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A process that involves the rearrangement of atomic structures, resulting in the formation of a new, different substance.

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Example: This diagram shows that in a chemical change, atoms are rearranged to form new substances, but the total number and type of atoms remain the same.

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Products Noun

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[prod-ukts]

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Products

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The new substances that are formed as the result of a chemical reaction, appearing on the right side of a chemical equation.

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Example: In a chemical reaction, the starting materials (reactants) rearrange their atoms to form new substances on the right side, which are called the products.

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Reactants Noun

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[ree-ak-tuhnts]

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Reactants

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The initial substances that undergo change during a chemical reaction, appearing on the left side of a chemical equation.

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Example: This diagram shows reactants (hydrogen and oxygen molecules on the left) combining in a chemical reaction to form a new product (water molecules on the right).

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Mass Noun

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[mas]

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Mass

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A measure of the amount of matter in an object, which remains constant regardless of the object's location.

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Example: This image compares different metric units of mass, like milligrams, grams, and kilograms, using common objects to show their relative scale.

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Open System Noun

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[oh-pen sis-tuhm]

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Open System

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A system that can freely exchange both energy and matter with its external surroundings.

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Example: This open pot on a hot plate is an open system because it exchanges both energy (heat from the hot plate) and matter (steam escaping) with its surroundings.

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Closed System Noun

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[klohzd sis-tuhm]

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Closed System

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A system that allows the transfer of energy but prevents the exchange of matter with its surroundings.

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Example: This diagram shows a sealed container (a bomb calorimeter) where a reaction can happen. The lid ensures no matter can get in or out, making it a closed system where mass is conserved.

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Isolated System Noun

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[ahy-suh-ley-tid sis-tuhm]

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Isolated System

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A system that is completely sealed from its environment, preventing any exchange of either energy or matter.

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Example: This diagram of a vacuum flask shows an isolated system, where the stopper prevents matter exchange and the vacuum layer prevents energy (heat) exchange.

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Atom Noun

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[at-uhm]

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Atom

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The smallest, fundamental unit of a chemical element that can exist and is conserved during a chemical reaction.

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Example: This diagram shows the parts of an atom: protons and neutrons in the central nucleus, and electrons orbiting in shells.