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Reaction Conversion, Yield and Selectivity Batch Log (Excel)

Yield alone does not tell you whether a poor batch lost material to unreacted feed or to side products. This worksheet logs each batch and computes conversion, yield and selectivity side by side, with totals and Excel export.

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Conversion	Yield	Selectivity
95%	85%	89.5%
92.5%	81.7%	88.3%
95.8%	88.3%	92.2%
87.8%	77.4%	88.1%
95%	86.7%	91.2%

Average conversion

93.2%

Average yield

83.8%

Average selectivity

89.9%

Yield equals conversion multiplied by selectivity. Use consistent units (kmol or kg-moles) for all three amounts. Measure unreacted reactant by sampling or in-process assay, and product by assay of the final mass.

Trend batch yield from your ERP data

Optional: we can review how yield and variance data are pulled from production orders.

Optional. The tool and every export work without this. No spam.

How to use it

Add one row per batch. Enter the limiting reactant charged, the amount still unreacted at the end, the desired product formed and the stoichiometric ratio from the balanced equation. The three percentage columns calculate themselves, and the totals show averages across the log. Replace the sample rows with your own and export to Excel or PDF for the batch review.

The definitions

Conversion is the fraction of limiting reactant consumed: (fed minus unreacted) divided by fed. Yield is product formed divided by the theoretical maximum. Selectivity is product formed divided by the product that would be obtained if all consumed reactant went to the desired product. So yield = conversion x selectivity.

Low conversion points to kinetics, time, temperature or catalyst
Low selectivity points to side reactions or poor mixing
Low yield with high conversion and selectivity suggests losses in work-up
Use moles, not mass, unless molar masses match

Common mistakes

Mixing mass and mole bases is the most common error and produces yields over 100 percent. Another is using the wrong limiting reactant. If a row shows selectivity above 100 percent, check the stoichiometric coefficient and measurement units before assuming the chemistry is better than the equation allows.

Account for recycled streams and heels separately
Record analytical method and date for traceability
Compare batches with the same raw material lot where possible
Trend the averages monthly rather than judging one batch

Frequently Asked Questions

What is the difference between yield and selectivity?

Yield compares product to the theoretical maximum from the full charge. Selectivity compares product to what the reactant that actually reacted could give. A batch can have good selectivity and poor yield if conversion is low.

Why does the worksheet show zero?

If a divisor is zero, for example the charge is blank or all reactant remains unreacted, the formula returns zero rather than an error. Fill in the charge and unreacted values.

Can I use kilograms?

Only if all columns use the same basis and the stoichiometric ratio is expressed in mass. For most chemistry, moles are cleaner. Convert with molar mass before entering the values.

What is a good yield?

It depends on the chemistry and process stage. Simple reactions may exceed 95 percent, multi-step fine chemical routes much less. Compare against your validated process targets and historical control limits.

If batch results are stored in your ERP production order history, Netray can help bring yield data into one trend view. Ask us for a review.

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