Thread: Water is the only substance...

I found this on one science web site, and it realy confused me:

"Water is the only substance that occurs at ordinary temperatures in all three phases: liquid, gas and solid."

As far as I know, many, many substances can be in all three phases at ordinary temperatures. Am I right?

I shall answer you with a question.

Which substances?

Well, any substance that is liquid at standard conditions could be solidified if pressure is aplied, without change of temperature. If pressure is lowered, substance will vaporise. And, even if liquid state is stable, it will always have vapor pressure, and so some vapor will exist above liquid.

Also substances that have melting point at about 10-20 degrees celsius can thus exist in S and L state at "ordinary" temperatures. And there is always vapor above L and S phases, however insignificant it might be. So even without changing pressure, you can achive all 3 states of mater inside "ordinary" temperatures.

1. I would read into the statement you quote that atmospheric pressure is implied.
2. I do not have the advantage of the context in which the quote is placed. However, I suspect they are talking about 'normal' general conditions, not micro-conditions.
3. So, name any substance which can exist in all three phases under 'normal' conditions.

But how can water exist in all three phases under normal conditions?

Originally Posted by munja100

But how can water exist in all three phases under normal conditions?

Water vapor in the air of the steaming jungle, liquid water in the ocean, and frozen water falling as snow.

Not the same conditions, but all are 'normal'.

or at the triple point - 273.16K and a Vapour pressure of 611.73P where water vapour, ice and liquid water exist in a happy little equilibrium.

water has an increddibly high electromagnetic binding. this keeps water together as a liquid. It reacts as a hexogen when it freezes, and by heat or uv it turns to vapor.

freezes at 0C° and turns to vapor at any heat... can be liquid between 0 and 100C° under 1 atm.

water rules..