Oxygen Candle: Chemical Oxygen Generator

Candle Composition

Candle length 250 mm

Iron fuel fraction 20%

Catalyst loading 100%

Insulation quality 100%

Live Readout

Standby — press Ignite

Burn front

0.0%

Core temp.

20 °C

O₂ output

0.0 L/min

O₂ produced

0.0 L

How it works

A chemical oxygen generator ("oxygen candle") burns a compressed core of sodium chlorate mixed with a powdered iron fuel. Once ignited it needs no outside power or air — the reaction sustains its own heat and propagates as a front along the candle, exactly as used on the ISS, in submarines, and in aircraft passenger-oxygen masks:

2 NaClO3 → 2 NaCl + 3 O2      (exothermic decomposition)
4 Fe + 3 O2 → 2 Fe2O3          (iron fuel sustains the heat)

The front speed follows an Arrhenius-type law — reaction rate rises exponentially with core temperature:

v(T) = v0 · k_cat · exp[ (Ea/R)(1/Tref − 1/T) ]
T = T0 + η · (k1·f_Fe + k0)      insulation η, iron fraction f_Fe

Every gram of candle that burns releases oxygen mass-fraction ≈ 45.1% (96 g O2 per 212.9 g of 2 NaClO3), converted to volume at STP (22.4 L/mol, M(O2)=32 g/mol):

m_burned = ρ · A · x_front
V(O2) = m_burned · 0.451 · (1 − f_Fe) / 32 · 22.4

Candle length — how much fuel is packed in; a longer candle burns longer at the same rate.
Iron fuel fraction — more iron raises core temperature and burn speed, but leaves less NaClO3 by mass, so O2 yield per gram drops.
Catalyst loading — a direct multiplier on reaction rate (barium peroxide-type accelerants in real candles).
Insulation — better insulation retains reaction heat, raising core temperature and front speed.

Burn time is accelerated here for visualization — a real candle this size takes minutes, not seconds.

Unburned fuel Burn front Spent ash

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