Heating a sealed glass bottle of liquid from 20'C to 90'C

[science squir]

Hi
I have people heating liquids in sealed glass Schott bottles in our lab if they cannot find any metal containers in our lab. These are 1 liter bottles they are approximately filling to 500ml with very aqueous solutions.
The bottles have not actually broken one, but Schott advises not to apply pressure to glass bottles.
What is the actual pressure inside the sealed glass bottle once it is heated to 90'C from 20'C?

Are there three things to consider?

1/ The Boyle gas law where PV/T = PV/T
So approx P of gas after heating is = ( 1atm * 363K ) / 293K = 1.23atm.
(I am assuming that in a closed glass container that the volume of the gas would not change significantly)

2/ The aqueous solution would expand by the thermal expansion of water. 500ml. Water thermal expansion coefficient of 206x10*-6 / 'C. From 20'C to 90'C. So the expansion is only about 0.07ml. So maybe not such a big influence on the pressure.

3/ Vapour pressure graphs for water show no increase in Vapour pressure until 100'C. I would have thought there would be some increase in pressure with evaporation of water below 100'C in a closed container?

So does that mean that the pressure has increased to approx 1.23atm within the sealed glass container with 500ml of aqueous solution heated from 20'C to 90'C?

Thanks

 

[Dr_Morbius]

The vapor pressure of water is ~525 mm Hg at 90°C so I don't know what graphs you used but they were wrong. But other than that your calculations are correct.

 

[science squir]

That is great. Thanks! I was reading the vapour pressure as Absolute not gauge, so that was my bad...

 

[munshiasad]

Use antoni eq

 

[alphy]

for your question. I would like to clarify a few things before answering your question. First, I am assuming that the liquid in the sealed glass bottle is water, since you mentioned its thermal expansion coefficient and vapor pressure graphs. Second, I am also assuming that the bottle is completely sealed, meaning no air can enter or escape during the heating process. With that in mind, let me address your three considerations.

1. The Boyle's Law states that the pressure and volume of a gas are inversely proportional at a constant temperature. In this case, as the temperature of the liquid increases from 20'C to 90'C, the volume of the gas inside the bottle would remain constant. Therefore, according to Boyle's Law, the pressure would increase from 1 atm to 1.23 atm. However, as you mentioned, this calculation assumes that the volume of the gas would not change significantly, which may not be the case in a sealed glass bottle.

2. As you correctly pointed out, the thermal expansion of the aqueous solution would have a minimal effect on the pressure inside the bottle. This is because the volume of water is much larger compared to the small expansion that occurs due to its thermal coefficient. Therefore, we can neglect this factor in our calculation.

3. The vapor pressure of water at 90'C is 0.75 atm, which is significantly lower than the pressure calculated in consideration 1. This means that the water would not evaporate to a significant extent at 90'C, and therefore, it would not have a significant impact on the pressure inside the sealed bottle.

Based on these considerations, it is safe to say that the pressure inside the sealed glass bottle would increase to approximately 1.23 atm when the liquid is heated from 20'C to 90'C. However, this calculation is based on certain assumptions and may not be accurate in real-world situations. It is always important to consider all factors and uncertainties when conducting scientific experiments. I hope this clarifies your question.