Why does the dilution formula C1V1 = C2V2 work?

Because adding solvent changes the volume but does not alter the absolute number of solute molecules. Since moles = concentration × volume, moles remain constant before and after dilution.

How do you account for chemical reagent purity on the bottle label?

If the reagent purity (assay) is 98%, divide the calculated theoretical mass by 0.98. Weighing this slightly higher mass compensates for the 2% inert impurities.

How do you convert weight-by-volume percent (% w/v) to molarity?

A 1% (w/v) solution contains 1 gram of solute per 100 mL, or 10 grams per Liter. Therefore, Molarity M = (10 × % Concentration) / Molecular Weight (MW).

Why must standard solutions be prepared in volumetric flasks rather than beakers?

Beaker graduation markings carry errors up to ±5%. Volumetric flasks are calibrated to within ±0.1% accuracy at 20°C, ensuring rigorous analytical precision.

What is the relationship between ppm and Molarity?

In dilute aqueous solutions where 1 L weighs approx 1 kg, 1 ppm equals 1 mg/L. To convert ppm to Molarity, divide ppm by (1,000 × Molecular Weight).

Molarity & Solution Dilution (C1V1 = C2V2) Calculator

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Calculate molar mass, required reagent weight, and stock solution dilution (C1V1 = C2V2) with step-by-step laboratory preparation protocols.

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Presets:

Common Lab Compounds:

Molecular Weight (MW, g/mol)

Target Concentration

Target Final Volume

Required Reagent Mass

14.61 g

m = M × V × MW = 0.5 mol/L × 0.5 L × 58.44 g/mol

Total Moles

2.5000e-1 mol

n = C × V = 250 mmol

Laboratory Preparation Protocol (SOP):

1. Weigh precisely 14.610 g of reagent.
2. Dissolve completely in approx. 400 mL of distilled/deionized water in a beaker.
3. Transfer to a volumetric flask and add solvent to reach the final volume of 500 mL.

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Chemistry Molarity (M = mol/L) & Solution Dilution (C1V1 = C2V2) Calculator

Molarity (M = moles per liter) constitutes the international metric benchmark for quantifying chemical concentration across biochemistry, analytical testing, pharmacology, and molecular biology.

Preparing precision buffers or stock titrations requires converting desired molarity and volume into mass (grams) using the solute's molecular weight (MW, g/mol), while diluting concentrated mother stocks demands exact C1V1 = C2V2 calculations.

OrvoKit Molarity and Dilution Calculator provides molecular weight presets for standard laboratory compounds (NaCl, NaOH, Glucose, Tris, EDTA), computes exact mass in grams and milligrams, and generates standardized preparation protocols (SOP).

Stoichiometric Mass-to-Mole Equivalences & Conservation of Moles

Mathematical derivations connecting molecular weights, solute mass, and molar conservation during volumetric dilution.

Molarity and Dilution Core FormulationsMathematical Formulation

Molarity M = moles / Liters = (mass m / MW) / Volume V(L) Required Mass m = M × V(L) × MW Dilution Equality: C₁ × V₁ = C₂ × V₂ Added Solvent Volume = V₂ - V₁

During dilution, adding pure solvent preserves the absolute number of solute moles (n = C × V), allowing exact volume calculation of stock aliquot required.

Preparing 500 mL of 0.15 M Sodium Chloride (NaCl, MW = 58.44 g/mol) saline

Volume Conversion to Liters500 mL / 1000 = 0.500 L0.5 L

Moles Calculationn = 0.15 mol/L × 0.5 L0.075 mol

Mass Evaluationm = 0.075 mol × 58.44 g/mol4.383 g

Protocol VerificationDissolve 4.383g NaCl in ~400mL H2O, then bring to 500mL mark0.15 M Saline

👉 Weighing 4.383 grams of NaCl and making up to 500 mL yields an exact 0.15 M physiological saline solution.

Standard Laboratory Chemicals Molecular Weight Reference Matrix

Benchmark molecular weights and primary applications across biochemistry and analytical labs

Compound Name	Formula	Molecular Weight (g/mol)	Physical State	Standard Laboratory Use
Sodium Chloride	NaCl	58.44	White crystal	Physiological saline, Osmotic balance
Sodium Hydroxide	NaOH	40.00	Hygroscopic pellet	Alkaline pH adjustment, Cell lysis
Hydrochloric Acid	HCl	36.46	Fuming liquid	Acidic titration, Buffer component
D-Glucose	C6H12O6	180.16	White powder	Cell culture media, Metabolic assays
Tris Base	C4H11NO3	121.14	White crystal	Biochemical electrophoresis buffers (TAE/TBE)
EDTA Disodium	C10H14N2Na2O8·2H2O	372.24	White powder	Metal ion chelator, Nuclease inhibitor
Copper(II) Sulfate	CuSO4·5H2O	249.68	Blue crystal	Biuret protein reagent, Fehling solution

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How to Use

11. Select Chemical Tool Mode

Choose between 'Molarity Mass Calculator' or 'Solution Dilution (C1V1 = C2V2)'.

22. Input Molecular Weight (MW)

Type the reagent's molar mass (g/mol) or pick from the common chemical compound buttons.

33. Specify Target Concentration & Volume

Select concentration units (M, mM, μM) and final solution volume (mL, L).

44. Review Mass & Preparation SOP

View the required scale mass (g/mg) and follow the step-by-step dissolution protocol, then click [Copy Result].

Biochemical & Experimental Applications

Common laboratory scenarios in buffer preparation, serial dilutions, and molecular biology

10X Stock Buffer Dilution to 1X Working Solution

Diluting 100 mL of 10X TAE stock with 900 mL of deionized water yields 1 L of 1X running buffer using C1V1 = C2V2.

Preparing 250 mL of 1.0 M Sodium Hydroxide

Weighing 10.00 g of NaOH pellets (40.00 g/mol × 1.0 M × 0.25 L) into an ice-cooled beaker safely manages the exothermic dissolution.

Oligonucleotide PCR Primer Dilution

Diluting a 100 μM reconstituted DNA primer stock 1:10 with sterile nuclease-free water yields a 10 μM working concentration.

💡 Wet Lab Best Practices and Safety Warnings

✓ Always Add Acid or Base to Water (Never Water to Acid)

Dissolving concentrated acids or strong bases generates significant exothermic heat; adding water to acid causes boiling splatter.

✓ Check for Hydrate Water of Crystallization

Always check whether your reagent bottle contains anhydrous powder or hydrated crystals (e.g. CuSO4 vs CuSO4·5H2O); hydrated waters add substantial mass.

✓ Never Dissolve Directly to the Final Mark

Dissolve solute in ~80% of final volume first, allow the solution to cool to room temperature (20°C), and then make up to the final meniscus.

⚠️ Common Pitfalls & Mistakes to Avoid

❌ Entering Desired Concentration Greater than Stock (C2 > C1)

✅ Dilution can only decrease concentration; target concentration C2 must strictly be less than stock concentration C1.

❌ Omitting Milliliter to Liter Conversion

✅ Molarity is moles per Liter; forgetting to divide 500 mL by 1,000 results in calculating 1,000 times too much reagent mass.

Frequently Asked Questions (FAQ)

Expert answers to the most frequently asked questions and edge cases.

6 Q&As

Molarity (M) is moles of solute per liter of solution, which varies slightly with temperature due to thermal expansion. Molality (m) is moles of solute per kilogram of solvent, which is strictly temperature-invariant.

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