# Feeling Salty (DD-285)

> Sodium is a soft alkali metal that reacts with water to form sodium hydroxide (caustic soda) and hydrogen gas, giving off heat. With larger pieces, that heat can ignite the hydrogen. A 2015 study in Nature Chemistry, filmed with high-speed cameras, suggested the violent start isn't just burning hydrogen: the metal loses electrons to the water so fast that the remaining positively charged metal ions repel each other and the surface bursts apart, a Coulomb explosion, exposing fresh metal. The title nods to table salt, sodium chloride, where sodium is tame and bound to chlorine. The footage shows a lump of metal thrown into a pond, then white bursts and spray on the water.

- Department: Science
- First published: 2024-07-30
- Last updated: 2024-07-30
- Permalink: https://detailenjoyer.com/case/feeling-salty/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-285-F01**: Sodium and water make sodium hydroxide and hydrogen. _(Write-up · Exhibit B (The products))_
- **DD-285-F02**: The initial burst may be a Coulomb explosion. _(Write-up · Exhibit D (Coulomb explosion))_

## Write-up

Drop sodium in a lake and the lake fights back. High-speed cameras suggest the first burst is a Coulomb explosion.

1. **Alkali metal**: Sodium is a soft, highly reactive alkali metal.
2. **The products**: With water it forms sodium hydroxide and flammable hydrogen gas.
3. **Heat and ignition**: The reaction releases heat that can ignite the hydrogen.
4. **Coulomb explosion**: High-speed video suggests the first burst is a Coulomb explosion of charged metal.
5. **Not table salt**: In table salt, sodium is bound to chlorine and doesn't react this way.

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- [Microwave Metal (DD-589)](https://detailenjoyer.com/case/microwave-metal/): I paired it with another dramatic reaction people try at home
- [A Real Hot Head (DD-300)](https://detailenjoyer.com/case/a-real-hot-head/): I paired it with another fast, hot reaction

## Reel vs. record

- **Note**: 'Releases hydrogen gas and heat which can ignite the hydrogen': right, though I'd add that research from 2015 suggests the explosive start is a Coulomb explosion, with the hydrogen fire coming after.

## Video: Feeling Salty: Drop Sodium in a Lake and the Lake Fights Back

- Duration: 12.0 s · Published: 2024-07-30
- File: https://detailenjoyer.com/assets/videos/C-ELhlNJlk8.mp4

### Transcript

DID YOU KNOW? Sodium is a highly reactive alkali metal that reacts violently with water. When sodium comes into contact with water it rapidly releases hydrogen gas and heat which can ignite the hydrogen causing a fiery explosion! NOW YOU KNOW!

## Questions & answers

**Q: What kind of element is sodium?**  
A: It sits in group 1 with lithium and potassium. _(Source: Write-up · Exhibit A (Alkali metal) · Wikipedia: Sodium)_

**Q: What gas does sodium release in water?**  
A: Sodium hydroxide forms too. _(Source: Write-up · Exhibit B (The products) · Wikipedia: Sodium)_

**Q: What can ignite the hydrogen?**  
A: Bigger pieces get hotter. _(Source: Write-up · Exhibit C (Heat and ignition) · Wikipedia: Sodium)_

**Q: What did high-speed cameras suggest starts the burst?**  
A: Charged metal ions repel and burst apart. _(Source: Write-up · Exhibit D (Coulomb explosion) · Mason et al., Nature Chemistry (2015): Coulomb explosion during the early stages of the reaction of alkali metals with water; Scientific American: Sodium's Explosive Secrets Revealed (Jan 27, 2015))_

**Q: Why doesn't table salt explode in water?**  
A: Sodium chloride is stable. _(Source: Write-up · Exhibit E (Not table salt) · Wikipedia: Sodium)_

## Sources

- [Wikipedia: Sodium](https://en.wikipedia.org/wiki/Sodium)
- [Mason et al., Nature Chemistry (2015): Coulomb explosion during the early stages of the reaction of alkali metals with water](https://www.nature.com/articles/nchem.2161)
- [Scientific American: Sodium's Explosive Secrets Revealed (Jan 27, 2015)](https://www.scientificamerican.com/article/sodium-s-explosive-secrets-revealed1/)

## Cite this case file

Easterling, Marcus. "Feeling Salty." The Detail Department (DetailEnjoyer), case file DD-285, last updated Jul 30, 2024. https://detailenjoyer.com/case/feeling-salty/