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32% HCl Solution Heat of Fusion

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

RE: 32% HCl Solution Heat of Fusion

In  the Handbook of chemistry and physics, The Chemical Rubber co, 52nd edition I found the melting point for HCl = -114,3degC and heat of fusion =476 cal/gmol(=13 cal/g).It does not say that it is 33w% but I think that any other value would be marked with a comment.
m777182

RE: 32% HCl Solution Heat of Fusion

The data above is for pure HCl (not an aqueous solution).

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://support.olisystems.com/ApplicationBriefs/MSE-Overview.PDF
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

(OP)
Thank you guys, specially Kevlach.
Actually I couldn't find any data on "Heat of Fusion" for aqueous HCl too.

RE: 32% HCl Solution Heat of Fusion

Probably, the value at this point has never been measured since this composition doesn't freeze (or melt) congruently; but rather, it goes through a 2-phase region, liquid + solid.

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



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