Percent Yield Calculator

Percent Yield Calculator

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Understanding Chemical Yield

In chemistry, "yield" refers to the amount of product you get from a chemical reaction. However, reactions in the real world are rarely perfect. The Percent Yield is the single most important measurement for determining how efficient a reaction was.

Key Concepts

  • Theoretical Yield: This is the maximum possible amount of product you could create, calculated assuming the reaction is 100% perfect and every single reactant molecule turns into product. This is a value you calculate on paper *before* an experiment.
  • Actual Yield: This is the amount of product you *actually* measure after running the experiment in the lab. You weigh this value on a scale.
  • Percent Yield: This is the ratio of what you *actually got* to what you *could have gotten*, expressed as a percentage. It tells you how successful your experiment was. A high percent yield (e.g., 90%) is excellent, while a low yield (e.g., 20%) means a lot of product was lost or the reaction didn't complete.

Frequently Asked Questions

Can percent yield be over 100%?

Theoretically, no. A yield over 100% implies you created matter from nothing, which is impossible. However, in a real lab, a yield over 100% is a common sign of experimental error. It almost always means your "actual" product is not pure and is contaminated with something else, like leftover solvent (e.g., water) or an unreacted starting material, which adds to its weight.

What factors can cause a low percent yield?

Many factors can reduce your actual yield:
Incomplete Reaction: The reaction may not have been left for long enough or at the right temperature to complete.
Side Reactions: The reactants may have formed other, undesired products.
Loss of Product: Product can be lost during transfer between containers, during filtration, or if some remains dissolved in a solvent.
Equilibrium: Many reactions are reversible, meaning they reach a point where products are turning back into reactants, so they never reach 100% completion.

Why is percent yield important in industry?

In industrial manufacturing (like for medicines or plastics), percent yield is directly tied to profitability. A low yield means wasted reactants, wasted energy, and less product to sell, all of which cost the company money. Chemists and engineers work constantly to optimize reactions to achieve the highest possible percent yield.