Rates of Reaction

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Rate Noun

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[rayt]

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Rate

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A ratio between two related quantities in different units, often describing how much something changes within a specified time.

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Example: This diagram explains rate using speed as an example, showing that it is a measure of how much distance is covered in a certain amount of time.

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Reaction Rate Noun

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[ree-ak-shun rayt]

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Reaction Rate

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The speed at which reactants are converted into products, typically measured as the change in concentration over time.

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Example: This image shows iron powder reacting with hydrochloric acid to produce gas bubbles, illustrating a chemical change happening over time, which is the basis for reaction rate.

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Concentration Noun

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[kon-sen-tray-shun]

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Concentration

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The amount of a substance in a defined space or volume, often expressed in moles per liter (mol/L).

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Example: This image shows that a concentrated solution has a lot of solute (like salt) dissolved in a solvent (like water), while a dilute solution has only a little bit.

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Reactant Noun

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[ree-ak-tant]

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Reactant

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A substance that takes part in and undergoes change during a chemical reaction.

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Example: This diagram shows that methane and oxygen are the starting substances, or reactants, that combine and change during a chemical reaction.

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Product Noun

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[prod-ukt]

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Product

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A substance that is formed as the result of a chemical reaction.

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Example: In a chemical reaction, reactants (like hydrogen and oxygen) combine to form new substances called products (like water).

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Stoichiometry Noun

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[stoy-kee-om-i-tree]

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Stoichiometry

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The relationship between the relative quantities of substances taking part in a reaction or forming a compound.

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Example: This image shows how a balanced chemical equation works, which is the basis of stoichiometry. Two hydrogen molecules and one oxygen molecule rearrange to form two water molecules.

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Collision Theory Noun

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[kuh-lizh-un thee-uh-ree]

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Collision Theory

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A model stating that reactions occur when particles collide with sufficient energy and the proper orientation.

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Example: For a chemical reaction to occur, molecules must collide with the correct orientation and enough energy. This image contrasts an effective collision with an ineffective one.

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Effective Collision Noun

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[ih-fek-tiv kuh-lizh-un]

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Effective Collision

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A collision between reactant particles that possesses enough kinetic energy and the correct orientation to cause a reaction.

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Example: For a chemical reaction to occur, reactant particles must collide with the correct orientation and enough energy to break old bonds and form new ones.

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Kinetic Energy Noun

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[ki-net-ik en-er-jee]

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Kinetic Energy

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The energy that a particle or object possesses due to its motion.

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Example: A ball rolling down a track has kinetic energy due to its motion. Similarly, molecules need sufficient kinetic energy to react when they collide.

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Surface Area Noun

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[sur-fis air-ee-uh]

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Surface Area

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The measure of the total exposed surface of a solid, which influences reaction rate by affecting collision frequency.

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Example: This image shows that a solid chunk (low surface area) has less exposed surface for reaction than the same solid as a powder (high surface area).