Reaction stoichiometry and limiting reagent calculator

What does this template do?

This workbook takes a balanced reaction with up to four reactants and three products and finds the limiting reagent. Enter each species' coefficient and molar mass, and the mass of each reactant used. The Reaction tab converts masses to moles, divides by each coefficient and takes the smallest value as the limiting reagent. That smallest value is the extent of reaction.

From the extent, the sheet calculates the theoretical yield of every product in moles and grams. Enter the actual yield of the main product to get the percent yield. For each reactant it shows the excess remaining in grams. The Scale-up tab takes a target mass of the main product and an expected percent yield, then sizes the moles and masses of each reactant, with an excess factor for the reagents that are not limiting.

The example is the aspirin synthesis from salicylic acid and acetic anhydride, with acetic acid as the second product. The masses, the 2.10 g actual yield and the 1.2 excess factor are example data. The coefficients are typed by hand, so balance the equation before entry.

What’s inside

• Limiting reagent found with INDEX and MATCH on the smallest moles per coefficient
• Extent of reaction, and theoretical yield in moles and grams for each product
• Percent yield from the actual yield of the main product
• Excess reagent remaining in grams for every reactant
• Scale-up tab sizes reactant masses for a target product mass and yield

Which tabs does the workbook have?

What formulas does this template use?

This template holds 60 formulas in 160 cells across 3 tabs, so 38% of its cells calculate. They use 7 distinct functions; the longest formula is 215 characters and 18 of them read from another tab.

Counted from the workbook itself. Only functions that Excel, LibreOffice Calc, Google Sheets and Apple Numbers evaluate the same way are used, so the formulas survive every download format.

How do you use it?

1. On the Reaction tab, enter each reactant's name, coefficient, molar mass and mass used.
2. Enter each product's coefficient and molar mass. The first product row is the main product.
3. Enter the actual yield of the main product, in grams, to get the percent yield.
4. Check the Status column and the excess remaining for each reactant.
5. On the Scale-up tab, enter the target mass, expected percent yield and excess factor.

What is it good for?

• Choosing which reagent to weigh in full
• Estimating the theoretical yield before a synthesis
• Checking the percent yield of a recrystallized product
• Sizing reagent masses for a larger batch

Questions about this sheet