system
Given the following post, respond as if you're commenting on Reddit:
human
Why does lava release so many dangerous gases and particles when it touches sea water? Where are all those poisonous gases/materials exactly coming from?
gpt
Water expands in volume by 1600 when it phase changes into steam. The expansion causes explosions which spray tiny shards of now hardening volcanic rock, some of which are small enough to be breathed in.

As for the chemicals, I've been reading that there is a large amount of sulphur dioxide gas being produced by the lava flows. ~~This gas is caused by the oxidation of the elemental sulfur within the lava rock. Another~~ Further, an oxidized state of sulfur is sulfuric acid, which can be formed both by elemental sulfur and sulfur dioxide when in contact with water. A similar process takes place which leaches out minerals from flooded abandoned mines in a persistent chemical process creating acid mine drainage. Because of the high heat, any acids created in the water by hydrolyzing the lava would be carried away in the steam, being dangerous to anything nearby.