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Reaction Equivalent Concentration from Mass & Volume

Calculate reaction-specific equivalents per volume from solute mass and a stated equivalents-per-mass factor.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A 10 g sample supplying 0.5 equivalents per gram in 2 L of solution gives 2.5 eq/L. The factor corresponds to an equivalent mass of 2 g/eq.

Equivalent concentration = solute mass × equivalents per mass / final solution volume

Worked example

Enter these known values and leave the other values blank.

Solute mass
10 g
Reaction-specific equivalents per mass
0.5 eq / g
Final solution volume
2 L
Reaction equivalent concentration
2.5 eq / L

Assumptions and limitations

  • All quantities are positive. Specify the reaction and equivalent entity before assigning equivalents per mass; the same compound may have different factors in different reactions.
  • Enter equivalents per mass, such as eq/g, rather than equivalent mass in g/eq. If you have equivalent mass, take its reciprocal first.
  • Normality is a historical name for reaction-specific equivalent concentration, commonly in eq/L. IUPAC and NIST recommend explicitly specifying the entity and amount concentration to avoid ambiguity.

Common questions

Can I enter equivalent weight directly?

No. This input is explicitly equivalents per gram or another selected mass unit. For an equivalent mass of 50 g/eq, enter 0.02 eq/g.

Does the calculator infer the reaction from a chemical name?

No. Supply the reaction-specific equivalents-per-mass factor yourself; it cannot be inferred from mass and volume alone.

References

Bookify multiplies solute mass by equivalents per unit mass, matching the displayed reciprocal-mass units; the captured equation incorrectly divided by that quantity. Bookify replaces the captured rounded US gallon with the exact 3.785411784-liter definition.

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