Sciencemadness Discussion Board

Hot Day cold acid!

NEMO-Chemistry - 19-7-2016 at 14:09

Today in the UK was hottest day of the year, around 2pm it dawned on me that my large container of HCl might benefit from being put in a bucket of cold water in the garage.

Its too big for the fridge at 5 Ltrs, so i went to pick it up and noticed the outside had condensation on it!

Its from a decent source and the container has a great seal on, the bottle didnt look like it was under pressure but touching the outside the bottle felt welt and cold!

The wet was water.

Why was/is this, its totally against what i would expect, outside temp was 31c woohoo, garage temp around 17C container temperature 5c!

wg48 - 19-7-2016 at 16:19

Its condensation.

The humidity has been high here in the UK. At such times condensation will form any object that about 10C or more lower than the air temperature. It formed on the floor of the north facing extension of my house and any objects on it. See the attached graph.




dew_point_graph.jpg - 35kB

NEMO-Chemistry - 19-7-2016 at 17:15

Quote: Originally posted by wg48  
Its condensation.

The humidity has been high here in the UK. At such times condensation will form any object that about 10C or more lower than the air temperature. It formed on the floor of the north facing extension of my house and any objects on it. See the attached graph.





Thanks it just felt strange feeling the acid container being so cold and yet in a room that was warmer, but makes sense the evaporation of the condensation cooled down the container

NEMO-Chemistry - 19-7-2016 at 17:16

The garage is great, seems well shaded so even in these temps the inside isnt that hot, even my pet ether seems ok in its box

Texium - 19-7-2016 at 21:49

Psh, I'd happily take 31ºC in the afternoon at this time of year... it's been near 40 and humid for most of this month. I've become a nocturnal creature.

wg48 - 20-7-2016 at 00:38

Quote: Originally posted by NEMO-Chemistry  
Quote: Originally posted by wg48  
Its condensation.

The humidity has been high here in the UK. At such times condensation will form any object that about 10C or more lower than the air temperature. It formed on the floor of the north facing extension of my house and any objects on it. See the attached graph.





Thanks it just felt strange feeling the acid container being so cold and yet in a room that was warmer, but makes sense the evaporation of the condensation cooled down the container


No. Condensation heats the objects that are initially cold

The garage and in particular its floor and objects on the floor tend to be at an average temperature ie lower than the day time temperature. So your bottle of acid is initially colder than the outside air during the day. Its been around 70% RH during the day (100% at night hence the dew on grass). If you look at the graph the dew point is less than 10C below the air temperature so any cool objects get condensation on them which heats them up until equilibrium is reached.

The condensation problem is worse at the moment because the heat spell has only been a few days so the average temperature is much lower than the day time temperatures and garage floors tend not to be insulated just like the stone cottage I live in.


[Edited on 20-7-2016 by wg48]

NEMO-Chemistry - 21-7-2016 at 12:00

Quote: Originally posted by wg48  
Quote: Originally posted by NEMO-Chemistry  
Quote: Originally posted by wg48  
Its condensation.

The humidity has been high here in the UK. At such times condensation will form any object that about 10C or more lower than the air temperature. It formed on the floor of the north facing extension of my house and any objects on it. See the attached graph.

Ah ok i understand now, it also gives me a good idea how to build a dew point propagator :D.

Everyone been moaning in the UK because it hit30C, stupid because a couple of weeks time everyone will moan its cold.



Thanks it just felt strange feeling the acid container being so cold and yet in a room that was warmer, but makes sense the evaporation of the condensation cooled down the container


No. Condensation heats the objects that are initially cold

The garage and in particular its floor and objects on the floor tend to be at an average temperature ie lower than the day time temperature. So your bottle of acid is initially colder than the outside air during the day. Its been around 70% RH during the day (100% at night hence the dew on grass). If you look at the graph the dew point is less than 10C below the air temperature so any cool objects get condensation on them which heats them up until equilibrium is reached.

The condensation problem is worse at the moment because the heat spell has only been a few days so the average temperature is much lower than the day time temperatures and garage floors tend not to be insulated just like the stone cottage I live in.


[Edited on 20-7-2016 by wg48]