Define User Data Form : Editing User Data

This Define User Data Form is for editing User Data and the edited user data will be saved in the currently specified user text file/user database; complilation into the user database will be automatically made after "OK" button is hit (related menu:Tools / User Data / Add a New Compound : Tools / User Data / Edit A Compound). This form consists of the following three pages with buttons:

• HGS_298 page; for editing the thermodynamic quantities at 298.15 K
• Phase page for High Temperature Heat Capacity
• Comment page
• Next Compound can be used to start a new compound with the new HGS_298 page.

(1) HGS_298 page

• to top to Phase page to Comment page
• 
• (1)Chemical Formula; (2)State (3)Functions at 298 K (4)Phase numbers at high temperatures

(1-1)Chemical Formula edit field

• This is to input the chemical formula.
• MALT adopts the special conventions for input chemical formula..
• The stoichiometric numbers for respective elements are given by decoding the chemical formula.
• When MALT will fail to decode the chemical formula, an error message will be given.
• Error in inputting the stoichiometric numbers will cause serious error in the thermochemical quantities which are calculated from the stoichiometric numbers and input thermodynamic functions.

(1-2) State Information

• Phase at 298.15 K
• Phase symbol at 298.15 K should be selected among g, a, l, s, c. MALT uses g for gas, a for aqueous, l for liquid, c for crystal. In addition s is allowed for solid.
• Elevated Phases
• High temperarture phases should be selected among s, l, sl, a, g; s is for solid including crystal, amorphous etc.
• This implies that gaseous species and aqueous species should be prepared as single-state data, while solid and liquid states can be combined in one compound data.
• These differences in the Elevated Phases will be used when the retireived compound data will be rearranged in the Menu:Tools/Data Format Conversion using Data Format Conversion Form.

(1-3) Functions at 298 K

• Three Fundamental functions:
• Standard Enthalpy of Formation
• Standard Gibbs Energy of Formation
• Standard Entropy
• Consistent Check button
• This is to check the above three quantities with stoichiometric numbers according to the following relation:
• Δ_fG = Δ_fH - T Δ_fS
• Δ_fS(A_lB_mC_n) = S₂₉₈(A_lB_mC_n) - l S₂₉₈(A) - m S₂₉₈(B) - n S₂₉₈(C)
• The MALT database stores the values for S₂₉₈(A), S₂₉₈(B) and S₂₉₈(C).
• Alternative check button: All three values are given under the consitions that the standard pressure is adopted as 1 atm and the energy unit is based on Joul. Even so, there must be some needs to input values adopted uder the standard pressure of 100,000 Pa or in the unit of cal instead of J. To assist such value input, this check botton is prepared.

(1-4) Phase number at high temperatures

• Number of Phases: this value should be >0 and <10.
• Define Phase Data button : By hitting this button, the numbers of high temperature heat capacity pages will be created and shown like "Phase_1".

(2) Phase page for input High Temperature Heat Capacity;

• to top to HGS_298 page to Comment page
• 
• (1) Phase Name (2) Cp coefficients (3) Temperature range (4) Transition (5) Phase buttons

According to the selected number of the phases, the high temperature heat capacity pages will be created. For each phase, the following should be input.

(2-1) Phase name

• Name : This is the phase name which identifies the current state among the high temperature states. Usually, if the phase is identified as alpha, beta etc, this is adopted. For example, Al2O3 alpha
• Symbol : In the MALT database, the following name is usually adopted: c1, c2, c3,,, l, l1, where numbering is adopted when several crystal polymorphs are known.

(2-2) Heat Capacity Coefficients

The heat capacity coefficients, a, b, c, d, e are defined in the following equation.

• C_p / J mol^-1 K^-1 = a + b * 10^-3 T/K + c * 10⁵ (T/K)^-2 + d * 10^-6 (T/K)² + e * 10⁸ (T/K)^-3

The first three terms represents the typical temperature dependence of the high temperature heat capacity. The fourth term is to cover the rapidly increasing effect at high temperatures. The fifth term is to represent intermediate-temperature behavior for those compounds having the high Debye temperature.

(2-3) Temperature Range

This is the valid temperature range of the present heat capacity coefficients characterized in the following two terms:

• Lower limit ; When the previous phase is available, this should be the same as the higher limit of the previous phase.
• Higher limit : This is the transition temperature when the next phase is available.

(2-4) Transition Data

When the higher temperature limit corresponds to the phase transition, the following should be input:

• Delta H : Transition enthalpy in kJ/mol.
• Symbol : MALT uses the following symbols:
• mp :melting point
• tp : transition point
• dp : dissociation point
• bp : boiling point
• mtp : magnetic transition point
• ltp : lambda transition point
• $ : no physical meaning

(2-5) Phase Buttons

• Move to left : Move to the previous high temperature heat capacity page.
• Move to right : Move to the next high temperature heat capacity page.
• Insert : One new high temperature heat capacity is added just after the current page.
• Delete : The current page will be deleted.
• Copy : Heat capacity coefficients are stored in clipboard as text format.
• Paste : When the clipboard text is for the heat capacity, those text is pasted in the respective coefficient fields,
• End : This ends the edition of the present high temperature heat capacity page.

(3) Comment page

to top to HGS_298 page to Phase page to Comment page

At present, only a string in 80 characters is allowed as comment.