CN102121911B - Method for researching standard molar enthalpy of formation of grenade-shaped nano-ZnO (zinc oxide) - Google Patents

Abstract

The invention provides a new idea for the first time that the known standard molar enthalpy of formation of blocky ZnO (zinc oxide) is taken as a reference standard to seek the relation between the standard molar enthalpy of formation of the grenade-shaped nano-ZnO and the blocky ZnO so as to obtain the standard molar enthalpy of formation of the grenade-shaped nano-ZnO. On the basis of the new idea, the invention further provides a new method. In the method, the grenade-shaped nano-ZnO and the blocky ZnO respectively perform the same chemical reaction under the same condition so as to obtain the standard molar enthalpy of formation of the grenade-shaped nano-ZnO. In the invention, the standard molar enthalpy of formation of the grenade-shaped nano-ZnO under 298.15K and Ptheta is minus 199.41kJ/mol obtained by utilizing a micro calorimeter with high precision and high sensitivity according to a thermodynamic potential function method.

Description

A kind of method of studying grenade-shaped nanometer ZnO standard molar formation enthalpy

Technical field

The present invention relates to a kind of research of grenade-shaped nanometer ZnO standard molar formation enthalpy; Be particularly related to a kind of with known block ZnO standard molar formation enthalpy standard as a reference; Seek the relation of grenade-shaped nanometer ZnO and block ZnO standard molar formation enthalpy, thereby obtain the method for grenade-shaped nanometer ZnO standard molar formation enthalpy.

Background technology

Regulation thermodynamic functions such as the entropy of nano material, enthalpy, Gibbs free energy have important scientific meaning and using value, and are the functions of yardstick and pattern.How obtain the regulation thermodynamic function value of nano material through experiment; Explore yardstick, orientation (pattern) relation and the development law of nanometer thermodynamic function; Setting up the basal heat mechanics data standard of different size, different orientation (pattern) nano material, is the important topic of " nano material thermodynamics " research.Current the nano material Study on Thermodynamic Properties extremely is short of, especially to the research of regulation thermodynamic function values such as the entropy of nano material, enthalpy, Gibbs free energy.

Yue Danting etc. have measured the low temperature thermal capacitance of multiple different nano material (like nano zine oxide, nanometer iron, nano aluminum) through identical method, and according to the relational expression of thermal capacitance and thermodynamic function, having obtained with standard state 298.15K is entropy, enthalpy, the Gibbs free energy of the nano material of benchmark; Its representative document is like [Yue Danting; Tan Zhicheng, Dong Lina, Sun Lixian; Open great waves. Acta PhySico-Chimica Sinica 2005,21:446-449.]; Come binding isotherm models such as luxuriant roc, the various standard enthalpys that obtained the different-grain diameter Nano diamond with the method for quantum chemistry and standard entropy [luxuriant roc, Xue Yongqiang, Lian Peng, Ge Zhongxue, Wang Baizhou, Zhang Zhi's loyalty. Acta PhySico-Chimica Sinica 2007,23:508-512.]; Yuan Aiqun etc. utilize little calorimeter, and the reaction heat through the nanometer reaction system has obtained the standard molar formation enthalpy data of the multiple nano phosphate compound of solid phase reaction preparation, and its representative document is like [a) Yuan AQ, Liao S, Tong ZF; Wu J, Huang ZY.Mater.Lett.2006,60:2110-2114.b) Yuan AQ, Wu J; Bai LJ, Huang ZY, Wu K, Liao S; Tong ZF.Mater.Res.Bull.2008,43:1339-1345.c) Yuan AQ, Wu J, Bai LJ; Ma SM, Huang ZY, Tong ZF.J.Chem.Eng.Data 2008,53:1066-1070.].

More than the problem that exists of these methods be: the entropy through measuring the nano material that the low temperature thermal capacitance obtains, enthalpy, Gibbs free energy are benchmark with standard state 298.15K rather than are benchmark with 0K, therefore from not solving the regulation thermodynamic function value of nano material in fact; The foundation of theoretical model and application only are fit to satisfy the nano material of specified conditions, so the scope of application is narrow and small; Reaction heat through the nanometer reaction system obtains the standard molar formation enthalpy of nano material, and standard molar formation enthalpy that must known each material except that nano material is also inapplicable to liquid phase reactor.At present, with known block materials standard molar formation enthalpy standard as a reference, seek the relation of nano material and the corresponding block material standard mole enthalpy of formation, thereby the thought and the concrete grammar that obtain the nano material standard molar formation enthalpy were not reported also.

Summary of the invention

The objective of the invention is in order to overcome defective that above-mentioned existing method exists and not enough and a kind of new thought and new method of obtaining the nano material standard molar formation enthalpy that provide, this new thought has obtained checking through concrete new method, has supported this new thought.

The object of the invention can be realized through following technical scheme: a kind of new thought and new method of studying grenade-shaped nanometer ZnO standard molar formation enthalpy; It is characterized in that new thought is with known block ZnO standard molar formation enthalpy standard as a reference; Seek the relation of grenade-shaped nanometer ZnO and block ZnO standard molar formation enthalpy, thereby obtain grenade-shaped nanometer ZnO standard molar formation enthalpy.New method is based on that this new thought specifically sets up; Being specially under the same conditions, identical chemical reaction takes place respectively in grenade-shaped nanometer ZnO and block ZnO; According to the thermodynamic potential function method; Obtain the relation of grenade-shaped nanometer ZnO and block ZnO standard molar formation enthalpy, finally obtain the new method of grenade-shaped nanometer ZnO standard molar formation enthalpy.The feasibility study of this new method the correctness of this new thought.Concrete steps are following:

1), at 298.15K and p ^θDown, with grenade-shaped nanometer ZnO and block ZnO respectively with the hydrochloric acid reaction of excessive same concentration, utilize little calorimeter to measure the reaction enthalpy change of zinc-oxide nano reaction system and block reaction system respectively;

2), react completely after; Utilize inductively coupled plasma (being called for short ICP) to measure the concentration of zinc ion in ZnO nanometer reaction system and the block reaction system; To confirm the amount of zinc paste reaction in two kinds of systems, obtain the molar reactive enthalpy change

of two kinds of systems

3), according to the thermodynamic potential function method, set up the contact of ZnO nanometer reaction system and block reaction system, the relation that obtains grenade-shaped nanometer ZnO and block ZnO standard molar formation enthalpy is:

${\mathrm{\Δ}}_f{H}_{m,A}^{\mathrm{\θ}}(\mathrm{ZnO},\mathrm{bulk})-{\mathrm{\Δ}}_f{H}_{m,A}^{\mathrm{\θ}}(\mathrm{ZnO},\mathrm{nano})={\mathrm{\Δ}}_r{H}_m^{\mathrm{\θ}}\left(\mathrm{nano}\right)-{\mathrm{\Δ}}_r{H}_m^{\mathrm{\θ}}\left(\mathrm{bulk}\right);$

4), the standard molar formation enthalpy through known block ZnO, the relation of grenade-shaped nanometer ZnO and block ZnO standard molar formation enthalpy in the integrating step 3 obtains the standard molar formation enthalpy of grenade-shaped nanometer ZnO.

Compared with prior art, the present invention has following characteristics:

1, new thought is to be based upon on the basis of standard molar formation enthalpy of block materials, because the standard molar formation enthalpy of block materials can obtain through looking into handbook among the present invention.

2, new thought is to serve as theme with the relation of the standard molar formation enthalpy of seeking grenade-shaped nanometer ZnO and block ZnO among the present invention.

3, the new method among the present invention has connected the standard molar formation enthalpy of grenade-shaped nanometer ZnO and block ZnO dexterously.

4, the new method among the present invention has extensive applicability, and is simple to operate, to obtain data accurately quick.

Description of drawings

Fig. 1 implements to get in touch the principle schematic of thermodynamic potential function method of the standard molar formation enthalpy of grenade-shaped nanometer ZnO and block ZnO for the present invention;

Fig. 2 be in the embodiment of the invention 1 with the SEM figure of the grenade-shaped nanometer ZnO of hydrochloric acid reaction

Embodiment

Below in conjunction with specific embodiment the present invention is described further, the description of embodiment is merely is convenient to understand the present invention, but not to the restriction of the present invention protection.

Embodiment 1

1. at 298.15K and p ^θDown; With a certain amount of grenade-shaped nanometer ZnO and concentration is that 0.26mol/L, volume are that the excessive hydrochloric acid of 1.5mL places little calorimeter to react; Record reaction enthalpy and become-1.17567J; With the color comparison tube constant volume of reactant liquor with 10mL, use ICP to record zinc ion concentration and be 7.6972mg/L, the molar reaction enthalpy that draws the nanometer reaction system thus becomes-988.62kJ/mol;

2. at 298.15K and p ^θDown; With a certain amount of block ZnO and concentration is that 0.26mol/L, volume are that the excessive hydrochloric acid of 1.5mL places little calorimeter to react; Record reaction enthalpy and become-0.21925J; With the color comparison tube constant volume of reactant liquor with 10mL, use ICP to record zinc ion concentration and be 1.7070mg/L, the molar reaction enthalpy that draws the block reaction system thus becomes-839.75kJ/mol;

3. according to the thermodynamic potential function method, set up the contact of ZnO nanometer reaction system and block reaction system, the relation that obtains grenade-shaped nanometer ZnO and block ZnO standard molar formation enthalpy is:

${\mathrm{\Δ}}_f{H}_{m,A}^{\mathrm{\θ}}(\mathrm{ZnO},\mathrm{bulk})-{\mathrm{\Δ}}_f{H}_{m,A}^{\mathrm{\θ}}(\mathrm{ZnO},\mathrm{nano})={\mathrm{\Δ}}_r{H}_m^{\mathrm{\θ}}\left(\mathrm{nano}\right)-{\mathrm{\Δ}}_r{H}_m^{\mathrm{\θ}}\left(\mathrm{bulk}\right)$

298.15K and p ^θThe standard molar formation enthalpy of following block ZnO

Finally can get the standard molar formation enthalpy of grenade-shaped nano-ZnO

Claims (1)

1. method of studying grenade-shaped nanometer ZnO standard molar formation enthalpy, concrete steps are:

1), at 298.15K and p ^θDown, with grenade-shaped nanometer ZnO and block ZnO respectively with the hydrochloric acid reaction of excessive same concentration, utilize little calorimeter to measure the reaction enthalpy change of zinc-oxide nano reaction system and block reaction system respectively;

2), react completely after; Utilize inductively coupled plasma to be called for short the concentration that ICP measures zinc ion in ZnO nanometer reaction system and the block reaction system; To confirm the amount of zinc paste reaction in two kinds of systems, obtain the molar reactive enthalpy change

of two kinds of systems

3), according to the thermodynamic potential function method, set up the contact of ZnO nanometer reaction system and block reaction system, the relation that obtains grenade-shaped nanometer ZnO and block ZnO standard molar formation enthalpy is:

${\mathrm{\Δ}}_f{H}_{m,A}^{\mathrm{\θ}}(\mathrm{ZnO},\mathrm{bulk})-{\mathrm{\Δ}}_f{H}_{m,A}^{\mathrm{\θ}}(\mathrm{ZnO},\mathrm{nano})={\mathrm{\Δ}}_r{H}_m^{\mathrm{\θ}}\left(\mathrm{nano}\right)-{\mathrm{\Δ}}_r{H}_m^{\mathrm{\θ}}\left(\mathrm{bulk}\right);$

4), the standard molar formation enthalpy through known block ZnO, the relation of grenade-shaped nanometer ZnO and block ZnO standard molar formation enthalpy in the integrating step 3 obtains the standard molar formation enthalpy of grenade-shaped nanometer ZnO.

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