32% HCl Solution Heat of Fusion
32% HCl Solution Heat of Fusion
(OP)
Does anybody know (Latent) heat of fusion (Freezing) of solution of 32% (or 33%) hydrochloric acid? (In atmospheric pressure)?
I would apprecite if I know your reference too.
Thanks
I would apprecite if I know your reference too.
Thanks





RE: 32% HCl Solution Heat of Fusion
m777182
RE: 32% HCl Solution Heat of Fusion
The CRC Handbook of chemistry and physics, 79th edition, pages 8-65 to 8-66, 'Aqueous Solutions, Concentrative Properties,' gives freezing point depressions for solutions up to 12.0 wt% HCl at which the freezing point = -20.51oC.
Perry's Chemical Engineers' Handbook, 7th Edn., page 2-15 gives these melting points:
HCl [100 wt%] -111oC
HCl.2H2O [50.3 wt%] 0oC
HCl(aq.,45.2wt%) -15.35oC
HCl.3H2O [40.3 wt%] -24.4oC
HCl(aq.,12.0wt%) -20.51oC [from CRC Handbook]
At 32 wt% HCl, probably have solid + liquid (+ vapor) phases rather than a single melting point. Search for an HCl-H2O phase diagram.
Calculated and experimental vapor-liquid equilibria in the HCl–H2O system are given in Figure 1 at http
This figure suggests a possible eutectic point near 0.17 mole fraction HCl. Note: 32 wt% HCl = 0.1886 mole fraction, so maybe have a freezing range (solidus & liquidus).
RE: 32% HCl Solution Heat of Fusion
Actually I couldn't find any data on "Heat of Fusion" for aqueous HCl too.
RE: 32% HCl Solution Heat of Fusion
One approach: Find the H2O phase diagram & a CRC Handbook with table I mentioned above, extrapolate a liquidus curve to 32 wt% HCl (xHCl = 0.1886). Then find a good physical chemistry book and look up 'freezing point depression.'
For your solution, the molality mHCl = 12.9. Water has a freezing point depression factor
kf = 1.86 oK/1000 g,
so we can estimate the freezing point depression for ideal solution behavior as
ΔT = kf x mHCl
= 1.86 x 12.906
= 24.0 K
so the solution's estimated freezing point (for ideal behavior) = -24.0oC (249.15 K). Compare this to the actual freezing point depression of the phase diagram, extrapolated as necessary, to determine the non-ideal heat of solution (mixing) [recall that ΔHmix = 0 for ideal solutions]. Unfortunately, you have to model the solution behavior for both liquid and solid solutions.
So, to cut our work short, use the crude approximation
ΔHfusion ~ (1- xHCl) x ΔHfusion, H2O + xHCl x ΔHfusion, HCl
ΔHfusion, 32 wt% HCl ~ 0.8114 x 6.01 + 0.1886 x 2.0 kJ/mole
ΔHfusion, 32 wt% HCl ~ 5.25 kJ/mole