CN1595127A - Method for measuring thermodynamic data by utilizing phase balance - Google Patents

Abstract

It is a thermodynamics data measurement method by use of phase balance, which steps are the following: to join solute into the solvent or two immiscible solvents and make them balance and then measure the balance thickness of each phase and calculate the balance phase constant K<theta> by use of balance thickness; then uses -RTlnK<theta>=delta alpha<beta>Gm<theta> to get delta alpha<beta>Gm<theta>d uses delta alpha<beta>Gm<theta>=deltafGm<theta>(2)-deltafGm<theta>(1) to get the solute standard mole Gibbs functiondeltafGm<theta>(2); to use dlnK<theta>/dT=delta alpha<beta>Hm<theta>/RT<2> to get standard mole phase enthalpy delta alpha<beta>Hm<theta> and use delta alpha<beta>Hm<theta>=delta fHm<theta>:(2)-delta fHm<theta>(1) to get standard mole enthalpy delta fHm<theta>(2); to use (delta alpha<beta>Hm<theta>)/TP=-delta alpha<beta>Sm<theta> to get standard mole entropy delta alpha<beta>Sm<theta>; to use delta alpha<beta>Sm<theta>=Sm<theta>(2)-Sm<theta>(1) to get Sm<theta>(2),wherein deltafGm<theta>(1), deltafHm<theta>(1), Sm<theta>(1) are known quantity; deltafGm<theta>(2), deltafHm<theta>(2), Sm<theta> (2) are to be measured.

Description

Utilization balances each other and measures the method for thermodynamic data

Technical field

The invention belongs to the thermodynamic data in fields such as can be applicable to chemical industry, metallurgy, environment, medicine, biomaterial, specifically utilizing balances each other measures the method for thermodynamic data.

Background technology

Current measuring methods is to utilize chemical equilibrium method (its measuring method comprises calorimetry and electrochemical process), and some Δs are also arranged _fH _m ^θ(B), Δ _fG _m ^θ(B), S _m ^θ(B) data are calculated with law of Hess.The characteristics of available data are, the thermodynamic data of pure material is more, thermodynamic data in the electrolyte solution is also more, but the related data in the non-electrolytic solution that is made of non-aqueous solvent is few, and this respect data are measured all very difficult with existing method, and error is bigger, therefore is badly in need of a kind of new practical approach that is suitable for and measures relevant thermodynamic data in this professional domain.

Along with science and technology development, new non-aqueous solvent constantly occurs and uses.Increasing non-aqueous solvent is applied to as fields such as metallurgy, chemical industry, pharmacy, biologies.Because the limitation and the accuracy of the existing measuring method of thermodynamic data make relevant thermodynamics master data some blank occur, these blank will make further developing of this field product produce difficulty.Basic thermodynamic data will not influence the development of association area production technology entirely and improve, and will directly have influence on the quality of product.

Summary of the invention

The measuring method that the purpose of this invention is to provide a kind of new thermodynamic data.Its principle is that chemical equilibrium is applied to balance each other, and utilizing balances each other measures relevant thermodynamic data such as Δ _fH _m ^θ(B), Δ _fG _m ^θ(B), S _m ^θ(B).

The present invention utilizes material in two alternate migrations, measures Δ by the method that balances each other _fH _m ^θ(B), Δ _fG _m ^θ(B), S _m ^θ(B) etc., patent is proposed this new method.

The present invention is right about the process of balancing each other ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}=-\mathrm{RT}\ln K^{\mathrm{\&theta;}}$ The application of formula and K ^θWith the relation of Henry's constant, and introduced the mensuration of utilizing Henry's constant and obtained basic thermodynamic data Δ in the ideal dilute solution _fG _m ^θ(B), Δ _fH _m ^θ(B), S _m ^θ(B).

The object of the present invention is achieved like this: its concrete steps are solute to be joined in the solvent or solute is joined in the two immiscible solvents, make it to reach and balance each other; Survey the equilibrium concentration of each phase after the balance, utilize equilibrium concentration to calculate phase equilibrium constant K ^θUtilize then $-\mathrm{RT}\ln K^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}$ Obtain Δ _α ^βG _m ^θValue is utilized ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_f{G}_m^{\mathrm{\&theta;}}\left(2\right)-{\mathrm{\&Delta;}}_f{G}_m^{\mathrm{\&theta;}}\left(1\right),$ Obtain the standard molar formation Gibbs function Δ of this solute _fG _m ^θ(2) value is utilized again $\frac{d\ln K^{\mathrm{\&theta;}}}{\mathrm{dT}}=\frac{{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}}{{\mathrm{RT}}^2}$ Obtain standard mole phase enthalpy change Δ _α ^βH _m ^θ, utilize ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_f{H}_m^{\mathrm{\&theta;}}\left(2\right)-{\mathrm{\&Delta;}}_f{H}_m^{\mathrm{\&theta;}}\left(1\right)$ Obtain the standard molar formation enthalpy Δ _fH _m ^θ(2) numerical value; Utilize ${\left[\frac{\&PartialD;\left({\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}\right)}{\&PartialD;T}\right]}_P=-{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}$ Obtain standard mole phase transformation entropy Δ _α ^βS _m ^θNumerical value utilizes ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}=S_m^{\mathrm{\&theta;}}\left(2\right)-S_m^{\mathrm{\&theta;}}\left(1\right),$ Obtain s _m ^θ(2) standard molar entropy of this solute;

Δ _fG _m ^θ(1), Δ _fH _m ^θ(1), S _m ^θ(1) is known quantity;

Δ _fG _m ^θ(2), Δ _fH _m ^θ(2), S _m ^θ(2) be to be measured.

The following sub-argument test two parts of touching upon are illustrated

First

The theoretical argumentation

(1)

Vapor-liquid equilibrium

For certain volatile solutes B in the ideal dilute solution, 1mol substance B material enters gas phase mutually by solution:

B (c _B, solution)=B (P _B, gas phase)

Its process

Be made as idealized system

${\mathrm{\&mu;}}_B\left(g\right)={\mathrm{\&mu;}}_B^{\mathrm{\&theta;}}\left(g\right)+\mathrm{RT}\ln \frac{p_B}{p^{\mathrm{\&theta;}}}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

Liquid phase is an ideal dilute solution, works as P=P ^θThe time

(2), (3) formula substitution (1) formula,

Order

Order $\frac{P_B/P^{\mathrm{\&theta;}}}{c_B/c^{\mathrm{\&theta;}}}=Q,$ The formula the same with chemical reaction isotherm also arranged:

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}+\mathrm{RT}\ln Q$

The B component is when gas-liquid two-phase reaches balance ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m=0,$ Q during balance is K ^θ, so just should have

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}=-\mathrm{RT}\ln K^{\mathrm{\&theta;}}$

Here

Be the poor of two standard state chemical potentials, wherein μ _B ^θ(gas phase) is the standard conditions of ideal gas; μ _B ^θ(solution) is the standard conditions of solute in the ideal dilute solution, promptly under the temperature of solution, pressure, and C _B=1moldm ^-3, and still to satisfy Henry's law be P _B=k _BC ^θ, be an imaginary attitude.The equilibrium constant $K^{\mathrm{\&theta;}}=\frac{p_B/P^{\mathrm{\&theta;}}}{c_B/c^{\mathrm{\&theta;}}}=\frac{p_B}{c_B}\frac{c^{\mathrm{\&theta;}}}{p^{\mathrm{\&theta;}}}=k_B\frac{c^{\mathrm{\&theta;}}}{p^{\mathrm{\&theta;}}},$ $k_B=\frac{p_B}{c_B},$ k _BBe Henry's constant, so ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}=-\mathrm{RT}\ln K^{\mathrm{\&theta;}}$ Formula also can be write as

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}=-\mathrm{RT}\ln k_B/(\mathrm{Pa}\&CenterDot;\mathrm{mo}{l}^{-1}\&CenterDot;{\mathrm{dm}}^3)+\mathrm{RT}\ln \frac{P^{\mathrm{\&theta;}}/\mathrm{Pa}}{c^{\mathrm{\&theta;}}/\left(\mathrm{mol}{\&CenterDot;\mathrm{dm}}^{-3}\right)}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

By (4) formula, can carry out Δ like this _α ^βG _m ^θWith k _BBetween conversion, also as can be seen: Henry's constant k _BBe process B (c _B, solution)=B (P _B, gas phase) the experiment equilibrium constant.(4) purposes of formula is: can pass through k in principle _BMeasurement ask and calculate the Δ of certain material in different solvents _fG _m ^θ(B), Δ _fH _m ^θ(B), S _m ^θ(B), can enrich the thermodynamic data table.

To B (c _B, solution)=B (P _B, gas phase) and process, because

Δ wherein _α ^βG _m ^θCan try to achieve Δ by (4) formula _α ^βS _m ^θCan by ${\left[\frac{\&PartialD;\left({\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}\right)}{\&PartialD;T}\right]}_P=-{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}$ Formula obtains, Δ _α ^βH _m ^θCan by ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}+T{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}$ Formula is tried to achieve.Δ wherein _fG _m ^θ(B, gas phase), S _m ^θ(B, gas phase), Δ _fH _m ^θ(B, gas phase) tables of data is existing, then Δ _fG _m ^θ(B, solution), S _m ^θ(B, solution), Δ _fH _m ^θ(B, solution) can be asked.

Pressure is to k _BInfluence very little, when P departs from P ^θThe time, according to Planck-Van Laar equation

${\left\{\frac{\&PartialD;[{\ln k}_B/(\mathrm{Pa}{\&CenterDot;\mathrm{mol}}^{-1}\&CenterDot;{\mathrm{dm}}^3)]}{\&PartialD;P}\right\}}_T=\frac{V_B^{\&infin;}}{\mathrm{RT}}$

Because

Value is greater than 0, so P increases k _BAlso increase, but Value is much smaller than 1, so pressure is to k _BInfluence very little.When measuring, when p departs from P ^θWhen not being very big, the influence of pressure can be ignored.

(2)

Liquid-solid equilibria and liquid-liquid equilibrium

Thermodynamic data for the solute in pure material and the electrolyte solution is many, and the thermodynamic data in the non-electrolytic solution that is formed by various non-aqueous solvents is also not too complete.This paper mainly talks the measurement by the formed non-electrolytic solution thermodynamic data of all kinds of solvents.

Be dissolved in the solvent orange 2 A 1 for substance B (s) and constitute non-electrolytic solution.As long as it is less to satisfy the solubleness of B (s) in A1, again at measurable range, this can choose this solvent for most of materials.

When 1mol substance B (s) is dissolved in the solvent orange 2 A 1, its process can be expressed as:

B (s)=B (c _B, solution 1)

Corresponding reaction isotherm is:

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}+\mathrm{RT}\ln c_B/c^{\mathrm{\&theta;}}$

During balance ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m=0,$ Q=K ^θIts equilibrium constant K ^θ=c _B/ c ^θSo, K ^θCan be by measuring solubleness c _BTry to achieve, utilize

$-\mathrm{RT}\ln K^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&beta;}}----\left(1\right)$

${\left[\frac{\&PartialD;\left({\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}\right)}{\&PartialD;T}\right]}_P=-{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}----\left(2\right)$

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}+T{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}----\left(3\right)$

Δ wherein _fG _m ^θ(B, s), S _m ^θ(B, s), Δ _fH _m ^θ(B s) has in the table, then Δ _fG _m ^θ(B, solution 1), S _m ^θ(B solution 1), Δ _fH _m ^θ(B, solution 1) can in the hope of

Select a solvent orange 2 A 2 again, just passable as long as A2 and A1 do not dissolve each other, when in the system of A1, A2 coexistence, adding a small amount of solute B (s), make B both all less in the concentration of liquid phase, again all at measurable range,, can work as ideal dilute solution and handle because concentration is all less.When B reaches balance in the two-phase distribution, its equilibrium constant

K ^θ=[c _B, (solution 1)/c ^θ]/[c _B, (solution 2)/c ^θ]

K ^θCan try to achieve by surveying two phase concentrations, utilize (1), (2), (3) to obtain Δ _α ^βG _m ^θ, Δ _α ^βS _m ^θ, Δ _α ^βH _m ^θ

Δ _fG _m ^θ(B, solution 1), S _m ^θ(B, solution 1), Δ _fH _m ^θ(B, solution 1) is measured, so Δ _fG _m ^θ(B, solution 2), S _m ^θ(B, solution 2), (B, solution 2) can be asked.

Select solvent orange 2 A 3 again, A3 if with two kinds of solvents of A1, A2 in a kind ofly do not dissolve each other, just can constitute the another one biliquid is to use with quadrat method and obtain Δ _fG _m ^θ(B, solution 3), S _m ^θ(B, solution 3), Δ _fH _m ^θ(B, solution 3).Select solvent orange 2 A 4 again, if A4 can with preceding 3 kinds in a kind ofly can constitute biliquid system and just can ask Δ _fG _m ^θ(B, solution 4), S _m ^θ(B, solution 4), Δ _fH _m ^θ(B, solution 4).Select solvent orange 2 A 5, A6 later on again

The solvent condition of choosing is more and more wideer later on, so just can measure Δ in the multiple solvent _fG _m ^θ(B, solutions i), S _m ^θ(B, solutions i), Δ _fH _m ^θ(B, solutions i).

Known by (2) formula: temperature is influential to measurement result, measures in the steady water-bath of Ying Zaiheng.By ${\frac{d\ln K}{\mathrm{dT}}}^{\mathrm{\&theta;}}=\frac{{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}}{{\mathrm{RT}}^2}$ Formula can obtain LnK ^θRate of change to T.The influence of pressure is very little, by the Plank-VanLaar equation

${\left[\frac{\&PartialD;\left(\ln K^{\mathrm{\&theta;}}\right)}{\&PartialD;P}\right]}_T=\frac{{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{V}_m}{\mathrm{RT}}$

To solid-liquid equilibria

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{V}_m=V_B^{\&infin;}\left(1\right)-V_m\left(B\right)$

The biliquid that A1-A2 is constituted is

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{V}_m=V_B^{\&infin;}\left(1\right)-V_B^{\&infin;}\left(2\right)$

The molar volume of solid phase and the partial molar volume of liquid phase are more or less the same, and differ also very little between the partial molar volume of each liquid phase.So the influence of pressure is very little, can ignore.

The present invention is owing to utilize this method that balances each other can measure thermodynamic data in the multiple solvent, these thermodynamic datas can instruct relevant chemical industry, medicine, metallurgy, ore dressing, agricultural chemicals, material, environmental protection etc. many change the real work of relevant industry with material ' can be after people have had a concrete invention idea, utilize thermodynamic data to calculate, whether prove this idea with result calculated feasible, if it is not all right, whether can also changing old terms, to make it displacement feasible, just may carry out under what conditions.Can prove and check on for scientific research project verification, the new product development in above-mentioned each field.Can reduce human with natural struggle in avoid detours, do not walk unworkable road, do not do the unhelpful input of manpower material resources for impracticable project verification, be the guarantee of the limited financial resources of utilizing of science, material resources, manpower.The present invention has also that method is simple and practical, application cost is cheap,

To be described in further detail the present invention by example below, but following example only is the present invention's example wherein, the rights protection scope of not representing the present invention and being limited, the scope of the present invention is as the criterion with claims.

Second portion

Test and embodiment

Example 1 (liquid-solid equilibrium)

This experiment is surveyed the thermodynamic data of iodine in aqueous solution with solubility method

One, experiment purpose

1, understands solubility method and survey Δ _fG _m ^θ(I ₂, aq), Δ _fH _m ^θ(I ₂, aq), S _m ^θ(I ₂, principle aq)

2, understand the conventional method of measuring thermodynamic data

Two, experimental principle

As 1mol I ₂(s), water-soluble when reaching balance, its process can be expressed as:

$I_2\left(s\right)=I_2(c_{I_2},\mathrm{aq})$

K ^θWith the solubleness pass be: $K^{\mathrm{\&theta;}}=r_{I_2}{c}_{I_2}/c^{\mathrm{\&theta;}}$

Because the very little r of solubleness _I2→ 1, so just can measure K by the way of measuring solubleness ^θ, by

${-\mathrm{RT}\ln K}^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}----\left(1\right)$

Can be by measuring the K under certain temperature ^θAsk Δ _α ^βG _m ^θ, by

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_f{G}_m^{\mathrm{\&theta;}}(I_2,\mathrm{aq})-{\mathrm{\&Delta;}}_f{G}_m^{\mathrm{\&theta;}}(I_2,s)$

${\mathrm{\&Delta;}}_f{G}_m^{\mathrm{\&theta;}}(I_2,s)=0,$ Δ _fG _m ^θ(I ₂, aq) can ask Δ _fG _m ^θ(I ₂, aq 298.15K) can survey solubleness and try to achieve when 298.15K.By

${\left[\frac{\&PartialD;\left({\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}\right)}{\&PartialD;T}\right]}_P=-{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}$

As long as measure the solubleness of a series of different temperatures, ask Δ with (1) formula _α ^βG _m ^θ, make Δ _α ^βG _m ^θ(T)-T figure, and make the tangent line that T=298.15K is ordered, obtain its slope.Just can obtain Δ _α ^βS _m ^θ

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}=S_m^{\mathrm{\&theta;}}(I_2,\mathrm{aq})-S_m^{\mathrm{\&theta;}}(I_2,s)$

S _m ^θ(I ₂, s) check in the table.S _m ^θ(I ₂, aq) can ask.By

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}+\left(298K\right){\&times;\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}$

Can obtain Δ _α ^βH _m ^θ(298.15K)

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}={{\mathrm{\&Delta;}}_{f}H}_m^{\mathrm{\&theta;}}(I_2,\mathrm{aq})-{{\mathrm{\&Delta;}}_{f}H}_m^{\mathrm{\&theta;}}(I_2,s)$

Δ _fH _m ^θ(I ₂, be zero s), Δ _fH _m ^θ(I ₂, aq) can ask.

Three, instrument and reagent

Ultra thermostat (2), electric mixer, 250mL iodine flask (7), buret, each one in transfer pipet (25mL) graduated cylinder (10mL), 1% starch indicator, 10% KI aqueous solution, the new 0.0100moldm that demarcates ^-3Na ₂S ₂O ₃Standard solution, iodine (analyzing pure), 1000mL reagent bottle.

Four, experimental procedure

1, the ultra thermostat temperature transfers to 285.15K, 10g I is housed ₂(s) reagent bottle of 1000mL distilled water is put among the water-bath, stirs 60 minutes, stop pipetting supernatant 50mL in the reagent bottle of the potassium iodide that 10mL10% is housed after 10 minutes, constant temperature is after 5 minutes in the ultra thermostat of 285.15K, and the starch solution that adds 1mL1% is in iodine flask, with Na ₂S ₂O ₃Standard solution titration disappears just to blue.

2, ultra thermostat is transferred to 285.15k 290.15k, 295.15K, 298.15K, 305.15K, 310.15K, 315.15K respectively, all stirred 30 minutes after each temperature adjustment, after stopping 5 minutes, pipette the 50mL supernatant in the iodine flask that the 10mL10%KI aqueous solution is housed, constant temperature titration after 5 minutes in the 285k ultra thermostat.

Five, data processing

The experimental data table

T/k	285.15	290.15	295.15	298.15	305.15	310.15
							(c I2，aq)/mol.dm -3	9.87/ 10000	10.5/ 10000	12.1/ 10000	13.2/ 10000	16.1/ 10000	18.4/ 10000

The result data table

Δ fH m θ(I 2，aq) /(kj.mol -1)	S m θ(I 2，aq) /(j.k. -1mol -1)	Δ fG m θ(I 2，aq) /(kj.mol -1)
			20.89	131.7	16.43

Example 2 (vapor-liquid equilibrium)

The determination experiment of volatile solutes thermodynamic data

Dress 1dm benzene in the vial of 2L is with the syringe adding 50mlCH of 50ml ₄With build plug in the benzene, rock the water bath with thermostatic control of putting into 25.0 ℃ after a minute, get liquid phase 0.4ml with the 1ml syringe after 10 minutes, with the meteorological 40ml of the injector region of 50ml, measure content with gas chromatography respectively, converse c (CH ₄), P (CH ₄) (following CH ₄Represent with B) $k_B=\frac{p_B}{c_B},$ $K^{\mathrm{\&theta;}}=k_B\frac{c^{\mathrm{\&theta;}}}{p^{\mathrm{\&theta;}}}$ Calculate K ^θ=0.00637

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}=-\mathrm{RTl}{\mathrm{nK}}^{\mathrm{\&theta;}}=12558J.{\mathrm{mol}}^{-1}$

Wherein

Calculate

Example 3:(liquid-liquid equilibrium)

The mensuration of the solute thermodynamic data that solubleness is big

Experiment

Dress 1L water and the I that ground in the glass container of last figure ₂4g rocks after 10 minutes and adds 1LCCl ₄Rock the water bath with thermostatic control of putting into 25.0 ℃ after 10 minutes, put into 25.0 ℃ water bath with thermostatic control, get subnatant 0.4 μ l with 1 μ l syringe after 10 minutes, get upper strata liquid with 20 μ l syringes and get 10 μ l, measure with gas chromatography respectively

c _I22(HO)、c _I24(CCl)

$K^{\mathrm{\&theta;}}=\frac{c_{I_{2}2}\left(\mathrm{HO}\right)}{c_{I_{2}4}\left(\mathrm{CCl}\right)}=0.0117$

${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}=-\mathrm{RTl}{\mathrm{nK}}^{\mathrm{\&theta;}}=11026J.{\mathrm{mol}}^{-1}$

(liquid concentration is lower than 20mmoldm ^-3Concentration and activity are more or less the same, and liquid concentration should be controlled at this below concentration.)

Claims (2)

1, a kind of utilization balances each other and measures the method for thermodynamic data, and its method is: solute is joined in the solvent or solute is joined in the two immiscible solvents, make it to reach and balance each other; Survey the equilibrium concentration of each phase after the balance, utilize equilibrium concentration to calculate phase equilibrium constant K ^θUtilize then $-\mathrm{RT}\ln K^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}$ Obtain Δ _α ^βG _m ^θValue is utilized ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_f{G}_m^{\mathrm{\&theta;}}\left(2\right)-{\mathrm{\&Delta;}}_f{G}_m^{\mathrm{\&theta;}}\left(1\right),$ Obtain the standard molar formation Gibbs function Δ of this solute _fG _m ^θ(2) value is utilized again $\frac{d\ln K^{\mathrm{\&theta;}}}{\mathrm{dT}}=\frac{{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}}{{\mathrm{RT}}^2}$ Obtain standard mole phase enthalpy change Δ _α ^βH _m ^θ, utilize ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{H}_m^{\mathrm{\&theta;}}={\mathrm{\&Delta;}}_f{H}_m^{\mathrm{\&theta;}}\left(2\right)-{\mathrm{\&Delta;}}_f{H}_m^{\mathrm{\&theta;}}\left(1\right)$ Obtain the standard molar formation enthalpy Δ _fH _m ^θ(2) numerical value; Utilize ${\left[\frac{\&PartialD;\left({\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{G}_m^{\mathrm{\&theta;}}\right)}{\&PartialD;T}\right]}_P=-{\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}$ Obtain standard mole phase transformation entropy Δ _α ^βS _m ^θNumerical value utilizes ${\mathrm{\&Delta;}}_{\mathrm{\&alpha;}}^{\mathrm{\&beta;}}{S}_m^{\mathrm{\&theta;}}=S_m^{\mathrm{\&theta;}}\left(2\right)-S_m^{\mathrm{\&theta;}}\left(1\right),$ Obtain S _m ^θ(2) standard molar entropy of this solute;

Wherein: Δ _fG _m ^θ(1), Δ _fH _m ^θ(1), S _m ^θ(1) is known quantity;

Δ _fG _m ^θ(2), Δ _fH _m ^θ(2), S _m ^θ(2) be to be measured.

2, method according to claim 1 is characterized in that: solute can be that the involatile solute also can be a volatile solutes.