Synopsis: Tiny Bubbles Burn Just Fine

Bubbles of hydrogen and oxygen burn spontaneously if they are small enough.

Making things smaller often changes their behavior. For example, flammable gases don’t burn easily in micron-sized bubbles, because the relatively large surface area sucks away the heat needed to sustain combustion. But making the bubbles even smaller can reverse the situation.

In an article in Physical Review E, Vitaly Svetovoy of the University of Twente in the Netherlands and colleagues show evidence for spontaneous combustion in bubbles smaller than 200 nanometers in diameter. To generate hydrogen or oxygen gas from water, the researchers apply brief negative or positive voltage pulses to a submerged metal electrode. Nanobubbles of either gas alone persist and aggregate into larger bubbles. In contrast, rapidly alternating the voltage polarity creates mixed bubbles that disappear as the gases react.

The explosive combustion mechanically damages the nearby electrode and also causes a tiny but measurable heating of a nearby conductor used as a thermometer. The researchers suggest that in such small bubbles, surface tension creates many atmospheres of pressure that enhance the reaction, and fast dynamics may also influence the reaction. — Don Monroe


More Features »


More Announcements »

Subject Areas

Fluid DynamicsChemical Physics

Previous Synopsis

Materials Science

Doubly Shocked

Read More »

Next Synopsis

Quantum Information

Mirror, Mirror in Free Space

Read More »

Related Articles

Focus: <i>Video</i>—Liquid Drop Bursts into Thousands of Pieces
Soft Matter

Focus: Video—Liquid Drop Bursts into Thousands of Pieces

A drop of water-alcohol mixture on a layer of oil was caught on video bursting into thousands of tiny droplets. Read More »

Focus: Nanochannel Could Separate Mixed Fluids
Fluid Dynamics

Focus: Nanochannel Could Separate Mixed Fluids

Calculations show that capillary forces affecting a fluid mixture flowing through a nanochannel could be used to separate the mixture. Read More »

Viewpoint: Superfluids Hit the Street
Atomic and Molecular Physics

Viewpoint: Superfluids Hit the Street

A flow pattern dubbed the von Kármán vortex street, which is renowned for its aesthetic beauty and extreme power, has been created in a superfluid. Read More »

More Articles