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Dissolution of MgCO3 in HCL

Dissolution of MgCO3 in HCL

Dissolution of MgCO3 in HCL

I suppose the dissolution of MgCO3 in HCl is exothermic. However, I cannot find any reliable references confirming this. I am looking for the dissolution enthalpy of MgCO3 in HCl together with the references. May you please help if you can. I have been searching but it is not easy to find as I thought.

RE: Dissolution of MgCO3 in HCL

What species will you end up with? will everything be fully dissociated?
What do the free energies say?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Dissolution of MgCO3 in HCL

Exothermic, heat release is 50.4kJ/gm mole.


This reaction is probably based on pure aqueous HCL, so the reaction heat release will depend on the concentration of HCL you have to start with. And as the reaction proceeds in a batch reaction say, the concentration of HCl will change, and so will the heat of reaction at that point in time. I'm rather rusty on computing the enthalpy of HCL for varying solution strengths.

RE: Dissolution of MgCO3 in HCL

Write down the chemical reaction and use the delta H0 of each component to get the Delta H of the reaction.
Yes, exothermic reaction with the release of CO2.
Delta H0 are found in Thermodynamic handbooks (Lange for example), probably Perry too.
Good luck

RE: Dissolution of MgCO3 in HCL

Thank you all for your tips. To answer you separately:
@EdStainless: Its a dissolution reaction without precipitation. It would proceed as follows: MgCO3 (s) + 2HCl (aq) = MgCl2 (aq) + H2O (aq) + CO2 (g)
The HCl concentration will be 37 wt%. I have not yet gone deep into the free energies. I can get back to you later on this.

@Georgeverghese: Thank you for the reference. I came across this reference but I was looking for a more reliable reference that can be cited in journal article. So this means the value of 50.4 kJ/mole relates to a case where the concentration of all species is 100% and when we use 37% HCl, there is need to recalculate this value? I will try this.

@Pierreick: Thank you for this opnion. One question here is related to the question above that the heats of formation refer to the pure components and when we have 37% HCl, do these have to be recalculated? Is it possible that while the heat of reaction for the pure components is exothermic, it could change to endothermic when we dilute the HCl significantly or when the purity of the MgCO3 decreases significantly?

RE: Dissolution of MgCO3 in HCL

To comfort your idea, take samples of your Raw materials and perform the tests in the lab. Should not be too difficult.
My first thought will be that the reaction will take a longer time due to impurities and diluted acid.

RE: Dissolution of MgCO3 in HCL


HCl(g) -> HCl(aq)
MgCO3(s)-> MgCO3(aq)

MgCO3(aq) + 2HCl(aq) -> H20(l)+CO2(g)+MgCl3(aq)

Use published values for heats of formation

MgCO3 Heat of Solution: https://chem.libretexts.org/Courses/Howard_Univers...

HCl heat of Formation: https://atct.anl.gov/Thermochemical%20Data/version...[]=31&species_number[]=218&c1=-1&c2=1

You can find the other information readily online or in a chemistry reference. I can't be bothered to look everything up, but it is all readily available. Anecdotally, all neutralization reactions will be fairly exothermic.

To answer another of your questions, the heat of neutralization will not change if the HCl is diluted. Be aware that in situ dilution of HCl is also exothermic - you can look up values for heats of dilution for HCl based on concentration.

RE: Dissolution of MgCO3 in HCL

Using more dilute reactants doesn't change the energies, but it does change the final temperature reached.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Dissolution of MgCO3 in HCL

Yes, the exothermic heat of reaction will be less the more dilute the HCl solution is. This is, as @TiCL4 says, heat is released as you dilute pure HCL.

RE: Dissolution of MgCO3 in HCL

Thank you all for your input. I will work on this information?

RE: Dissolution of MgCO3 in HCL

Dolomite, extraction Magnesium with diluted Hcl.


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