Percent Yield

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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 study and calculation of quantitative relationships between the reactants and products involved in chemical reactions.

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Example: This diagram shows how atoms in reactants (methane and oxygen) rearrange to form products (carbon dioxide and water) in fixed ratios, a key principle of stoichiometry.

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Molar Mass Noun

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[moh-ler mas]

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Molar Mass

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The mass of one mole of a chemical substance, typically expressed in units of grams per mole (g/mol).

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Example: This diagram shows a glucose molecule (C6H12O6). To find its molar mass, you add the mass of all its atoms: 6 carbons, 12 hydrogens, and 6 oxygens.

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Molar Ratio Noun

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[moh-ler rey-shee-oh]

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Molar Ratio

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The ratio between the amounts in moles of any two compounds involved in a balanced chemical equation.

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Example: This diagram shows a balanced chemical reaction, visually representing the molar ratio: one methane molecule reacts with two oxygen molecules to produce specific products.

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Reactant Noun

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[ree-ak-tuhnt]

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Reactant

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A substance that is consumed at the start of a chemical reaction to be converted into new substances.

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Example: The reactants, hydrogen (H₂) and oxygen (O₂), are the starting ingredients on the left that combine to form the product, water (H₂O).

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Product Noun

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[prod-uhkt]

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Product

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

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Example: This diagram shows reactants (iron powder, hydrochloric acid) on the left combining to create a product (gas bubbles) on the right, illustrating a chemical change.

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Limiting Reagent Noun

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[lim-i-ting ree-ey-juhnt]

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Limiting Reagent

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The reactant that is completely used up in a reaction, thus determining the maximum amount of product formed.

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Example: This image uses a brownie recipe to show that the limiting reagent (the brownie mix) is the ingredient that runs out first, determining the maximum amount of product (brownies) that can be made.

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Excess Reagent Noun

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[ek-ses ree-ey-juhnt]

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Excess Reagent

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Any reactant that remains after the limiting reagent is completely consumed in a chemical reaction.

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Example: In a chemical reaction, the excess reagent is the reactant that is not fully used up. Here, oxygen runs out first, leaving leftover hydrogen atoms.

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Theoretical Yield Noun

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[thee-uh-ret-i-kuhl yeeld]

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Theoretical Yield

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The maximum amount of product that can be produced from the given reactants, calculated using stoichiometry.

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Example: This diagram shows that combining reactants (1 Kg of hydrogen + 1 Kg of oxygen) has a theoretical yield of 2 Kg, representing the maximum possible product.

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Actual Yield Noun

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[ak-choo-uhl yeeld]

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Actual Yield

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The measured amount of product that is actually obtained from a chemical reaction performed in a laboratory.

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Example: This image shows a digital balance, a tool used in a science lab to measure the mass of a substance. The actual yield is found by weighing the product of a chemical reaction on a balance like this.

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Percent Yield Noun

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[per-sent yeeld]

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Percent Yield

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A measure of a reaction's efficiency, calculated as the ratio of the actual yield to the theoretical yield.

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Example: This image shows a qualitative scale for evaluating percentages, loosely associating it with chemistry via a flask, but it does not explain what percent yield is.