About

Preparation of standard solutions is a fundamental task in analytical chemistry and biology. Errors in dilution can propagate through an entire experiment, rendering spectrophotometric data or titration results invalid. This tool assists laboratory personnel in calculating the precise volume of stock solution required to achieve a target concentration.

It handles the standard dilution equation for molar concentrations and addresses the more complex scenario of converting liquid stock reagents (typically labeled in Mass Percent, e.g., 37% HCl) into Molar solutions. This conversion requires the density and molecular weight of the solute, data points which are integrated directly into this calculator for over 50 common reagents.

Formulas

1. Basic Dilution (Molarity):

C₁V₁ = C₂V₂

Where:

C₁ = Initial Concentration (Stock)
V₁ = Volume of Stock needed (Unknown)
C₂ = Final Concentration
V₂ = Final Total Volume

2. Mass Percent to Molarity:

M = % × ρ × 10MW

Where ρ is Density (g/cm³) and MW is Molecular Weight (g/mol).

Reference Data

Chemical Name	Formula	MW (g/mol)	Density (g/cm³)	Standard Conc.
Acetic Acid	CH3COOH	60.05	1.05	99-100% (Glacial)
Hydrochloric Acid	HCl	36.46	1.19	37%
Sulfuric Acid	H2SO4	98.08	1.84	95-98%
Nitric Acid	HNO3	63.01	1.41	68-70%
Ethanol	C2H5OH	46.07	0.789	95% or Absolute
Sodium Hydroxide	NaOH	40.00	2.13	Solid Pellets
Phosphoric Acid	H3PO4	98.00	1.685	85%
Ammonium Hydroxide	NH4OH	35.04	0.90	28-30% NH3
Formic Acid	HCOOH	46.03	1.22	88%
Acetone	C3H6O	58.08	0.791	100%

Frequently Asked Questions

Always add Acid to Water (A→W), never water to acid. Strong acids, particularly Sulfuric Acid, react exothermically with water. Adding water to concentrated acid can cause the water to boil instantly, splashing corrosive acid out of the container.

Percentage concentration is typically weight/weight (w/w). Molarity is moles/volume. Density bridges the gap between weight (mass) and volume. Without knowing how much mass is in one milliliter of liquid (density), you cannot determine the number of moles present in that volume.

Yes. Liquid volumes change with temperature due to thermal expansion. Volumetric glassware (flasks, pipettes) is usually calibrated at 20°C. For high-precision analytical work, solutions should be brought to room temperature before final volume adjustment.

The dilution factor is the ratio of the final volume to the initial aliquot volume (V2 / V1). For example, if you dilute 1 mL of stock into 9 mL of solvent (Total 10 mL), the dilution factor is 10. The concentration decreases by this factor.