Curiosity question.  We keep a small fridge and the temp is kept quite cold.  When I take a bottle of sparkling water out, it is clearly in liquid form.  When I open it, within 5-20 seconds the better part of the bottle has turned into a frozen slush.

I'm aware that pressure can affect freezing temperature, but opening the bottle should lower the pressure which should actually raise the freezing temperature.  

What is happening here?  I'm stumped.

Several factors possibly in play

- It could be supercooled, and the bubbles are the disturbances that allow freezing.

- What you say about the freezing point isn’t an argument against this - if the system is at -2C, and under pressure freezes at -3 C, and you lower the pressure so the freezing point is -1 C, the liquid is suddenly below the freezing point. So it freezes

- CO2 coming out of solution reduces the freezing point depression, so it might now be below the freezing point, as above.

1 hour ago, CuriousOnes said:

Curiosity question.  We keep a small fridge and the temp is kept quite cold.  When I take a bottle of sparkling water out, it is clearly in liquid form.  When I open it, within 5-20 seconds the better part of the bottle has turned into a frozen slush.

I'm aware that pressure can affect freezing temperature, but opening the bottle should lower the pressure which should actually raise the freezing temperature.  

What is happening here?  I'm stumped.

Sherwood & Prausnitz (1962) give the following relation:

Enthalpy of Soln. (CO2) = 106.56 - 6.2634x10^4/T + 7.475x10^6/T^2    kJ/mol

Plug in 273.15 for T, and this gives around -22.6 kJ/mol at normal water freezing point.

So when you release the pressure, the heat of solution is lost to the escaping gas, and your drink autorefrigerates to a supercooled state, the released gas bubbles providing nucleation points for the formation of (typically) frazil ice. About 3g ice per litre of CO2 released as a rough estimate.

This effect may be enhanced by the factors mentioned above by Swansont.

Edited December 12, 20214 yr by sethoflagos
sp

2 hours ago, sethoflagos said:

Sherwood & Prausnitz (1962) give the following relation:

Enthalpy of Soln. (CO2) = 106.56 - 6.2634x10^4/T + 7.475x10^6/T^2    kJ/mol

Plug in 273.15 for T, and this gives around -22.6 kJ/mol at normal water freezing point.

So when you release the pressure, the heat of solution is lost to the escaping gas, and your drink autorefrigerates to a supercooled state, the released gas bubbles providing nucleation points for the formation of (typically) frazil ice. About 3g ice per litre of CO2 released as a rough estimate.

This effect may be enhanced by the factors mentioned above by Swansont.

Well researched and reported. +1

The presence of an impurity such as CO2 will lower the freezing point of water.
But my guess is that this is essentially a supercooling phenomenon.

16 hours ago, studiot said:

Well researched and reported. +1

40 years practice in fitting a chilled beer flash calc onto the back of a beer mat.