# Chemistry Calculators

Periodic table lookup, molar mass from formulas, mole conversions, dilution, pH, ideal gas, limiting reagent, empirical formula, bond polarity, half-life.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://chemistry-calc.x402tookit.com/openapi.json
- x402 manifest: https://chemistry-calc.x402tookit.com/.well-known/x402
- Catalog (free): https://chemistry-calc.x402tookit.com/catalog
- Health (free): https://chemistry-calc.x402tookit.com/health
- Uptime (free): https://chemistry-calc.x402tookit.com/uptime

## Endpoints (11)

### GET /bond-polarity — $0.02
Bond type between two elements from the Pauling electronegativity difference: nonpolar covalent, polar covalent or ionic.
Params: a: string, b: string
Example: https://chemistry-calc.x402tookit.com/bond-polarity?a=Na&b=Cl

### GET /dilution — $0.02
Dilution equation C1 x V1 = C2 x V2: give any three values and get the fourth, plus solvent to add and the dilution factor.
Params: c1?: number, v1?: number, c2?: number, v2?: number
Example: https://chemistry-calc.x402tookit.com/dilution?c1=12&c2=1&v2=500

### GET /element-lookup — $0.02
Periodic table lookup by symbol, name or atomic number: weight, configuration, electronegativity, melting and boiling points.
Params: element: string
Example: https://chemistry-calc.x402tookit.com/element-lookup?element=Fe

### GET /empirical-formula — $0.02
Empirical formula from percent or gram composition by element, and the molecular formula if you give the molar mass.
Params: composition: string, molarMass?: number
Example: https://chemistry-calc.x402tookit.com/empirical-formula?composition=C%3A40.0%2CH%3A6.7%2CO%3A53.3

### GET /half-life — $0.02
Radioactive decay: remaining fraction after a time, time to reach a fraction (carbon dating), decay constant and mean life.
Params: halfLife?: number, isotope?: string, elapsed?: number, remainingFraction?: number, initial?: number
Example: https://chemistry-calc.x402tookit.com/half-life?isotope=c-14&elapsed=11460&initial=100

### GET /ideal-gas — $0.02
Ideal gas law PV = nRT: give any three of pressure, volume, moles and temperature and solve the fourth, in common units.
Params: pressure?: number, volume?: number, moles?: number, temperature?: number, pressureUnit?: string, volumeUnit?: string, temperatureUnit?: string
Example: https://chemistry-calc.x402tookit.com/ideal-gas?pressure=101.325&pressureUnit=kPa&moles=1&temperature=273.15

### GET /limiting-reagent — $0.02
Limiting reagent, theoretical yield and leftover excess for a balanced reaction from reactant masses; optional percent yield.
Params: reactants: string, product: string, actualGrams?: number
Example: https://chemistry-calc.x402tookit.com/limiting-reagent?reactants=H2%3A2%3A4%3BO2%3A1%3A16&product=H2O%3A2

### GET /molar-mass — $0.02
Molar mass and percent composition by element for a formula, including brackets and hydrates such as CuSO4.5H2O.
Params: formula: string
Example: https://chemistry-calc.x402tookit.com/molar-mass?formula=C6H12O6

### GET /molarity — $0.02
Molarity of a solution from solute grams and volume, or the grams of solute needed to make a target molarity and volume.
Params: formula: string, volumeL: number, grams?: number, molarity?: number
Example: https://chemistry-calc.x402tookit.com/molarity?formula=NaCl&volumeL=0.5&molarity=0.15

### GET /mole-convert — $0.02
Convert between grams, moles and molecule counts for a chemical formula using Avogadro's number.
Params: formula: string, grams?: number, moles?: number, molecules?: number
Example: https://chemistry-calc.x402tookit.com/mole-convert?formula=H2O&grams=18.015

### GET /ph-calc — $0.02
pH and pOH for a strong or weak acid or base, a hydrogen-ion concentration, or a buffer (Henderson-Hasselbalch).
Params: mode: string, value?: number, concentration?: number, protons?: integer, ka?: number, kb?: number, pka?: number, acidConc?: number, baseConc?: number
Example: https://chemistry-calc.x402tookit.com/ph-calc?mode=weak-acid&concentration=0.1&ka=0.000018

## Terms

Results are computed locally from standard atomic weights (IUPAC abridged values via NIST) and textbook formulas, provided as is, for ideal conditions. Real solutions and gases deviate from ideal behaviour, and weak-acid and buffer results assume dilute solutions at 25 C. This is a calculation aid for study and planning, not a safety assessment: follow your lab's procedures and safety data sheets when handling chemicals.