What This Calculator Does and Why You Should Use It

Are you facing one too many chemistry problems sets tonight? Struggling with stoichiometry? Or trying to remember that last chemistry class (20 years ago) as you crunch through the math for a problem at work (or help your kid with their chemistry homework? Then this site is for you!

This particular calculator is a theoretical yield calculator for chemical reactions. A theoretical yield calculation solves for the maximum amount of product and excess reagent that will be consumed / created. We use the molar ratio of reactant in a balanced chemical reaction to understand how much product will be created under ideal conditions. (you may also be asked to compare your yield calculations with actual yield, which captures the impact of impurities & process inefficiencies).

Weigh how much of each reactant you are going to put into the process, look up molar weight and mole ratio (number of moles consumed per mole of reactant), and enter them into the calculator. The theoretical yield calculator will tell you how many grams of product the chemical reaction will generate. We have an additional percent yield calculator which can help you translate this into predictions for actual experiments.

Its important to remember the process uses molecular weight to capture the difference in molar mass between different types of reactant. For example, ammonia and acetic acid have very different molecular weights, which affects the volume of any reaction between them.

Bookmarking, Save, and Share Results

The tool is designed so you can flip between different parts of a problem set. We recommend you bookmark it so you can refer back to it. You can also share results with a study partner or tutor by hitting calculate and copying the URL for this page. When your study partner opens up the URL, they will see your calculations. Its easy share & save results via email. (Be sure to hit calculate first, however)

You also have the option of saving links to the calculations in your research notes files, so you can quickly re-open or check them later. Again - hit calculate first so the URL is updated with your most recent changes. Then copy and save the url.

FAQ - Theoretical Yield Calculator

What is Theoretical Yield in Chemistry?

The theoretical yield definition of a chemical process is the amount of product that will theoretically be generated by a chemical reaction under perfect conditions. Perfect conditions include, but are not limited to: fully consuming the available reactant, no impurities in the reactants, no production of unexpected byproducts which can reduce the yield, and no losses due to any measurement, processing, and handling of reactants or products.

How Do You Calculate Theoretical Yield?

The basic equation is:
grams product = grams reactant x (1 mol reactant/molar mass of reactant) x (mole ratio product/reactant) x (molar mass of product/1 mol product)

For a theoretical yield example, assume we have 20 grams of hydrogen gas and hydrogen gas has a molar weight of 2. Assume it can react with other reagents to create a molecule with a molar weight of 250, being consumed at a molar ratio of .2 (5 units of hydrogen per unit of product. What is the theoretical yield in grams for this reaction? Using the theoretical yield equation above, we know our 20 grams of hydrogen will yield: 20 x 1/2 x 1/5 x 250 = 500 grams of product.

How to Calculate Theoretical Yield in Chemistry

The individual steps of the process of calculating theoretical yield looks like this:

  1. Weigh your initial reactant.
  2. If you have multiple reactants (typical), weigh each reactant and keep in mind the one with the fewest grams of resulting product will be the limiting reagent for this reaction.
  3. Convert the weight of each reagent into moles, using the molar weight of the reagent (weight in grams of a mole of reagent)
  4. Balance The Chemical equation for the reaction to get the mole ratio - how many moles of product are generated by each reagent? (use the balanced equation to figure out the limiting reactant; the excess reactant doesnt participate in the event).
  5. If you multiply the previous numbers together, you will get how many moles of product can be created from that amount of reagent. The next step is to convert this into grams of product. We do this by multiplying the moles of product by the molar weight of the product.
  6. The answer is the number of physical grams of product that will be created through the reaction, under perfect conditions

What Does The Theoretical Yield Formula Calculator Do?

The theoretical yield calculator takes the yield equation above and solves it, determining theoretical yield. Remember to run the calculation for each reagent (and use a balanced chemical equation to solve for usage).

How Do I Find The Limiting Reagent?

Enter the details of each reagent participating in the reaction into the theoretical yield calculator. The theoretical yield calculator will tell you how many grams of product each reagent can produce, if fully consumed with no byproducts. The reagent with the smallest theoretical yield (in grams of product) is the limiting reagent for the chemical reaction.

How Do You Estimate Actual Yield?

We added an additional field to this calculator so you can quickly translate the results into an actual yield. This is defaulted to 100 percent (for the theoretical yield calculator). If you change it from 100 percent, it will also display actual yield (in grams of product). If your are working on a higher level problem set that with actual / theoretical yields (as a given, vs grinding through the molar math), you can use our percent yield calculator to work through those questions. That calculator is designed to take two of the following numbers and solve for the third: actual yield, theoretical yield, percentage yield.

What is the Stoichiometric Ratio?

The stoichiometric ratio of a reagent defines the optimum amount where, assuming that the reaction is allowed to finish:

  • All of the reagent is consumed
  • There is no deficiency of the reagent
  • There is no excess of the reagent.

Finding Molar Mass for Specific Compounds

Our molar mass calculator has this for a variety of other compounds: sodium chloride, carbon dioxide, sulfuric acid, glucose...

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