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SPECIFIC HEAT CAPACITY HELP

Allows for the prediction of liquid heat capacities of a compound at 20 Degrees Celsius . The prediction is based upon the group contributions of each individual component of the compound.

Chemical Data > Pred. Of liquid Heat Cap. Calculations

Method Of Use :

Determine the chemical groups of the compound which the heat capacity needs to be determined for.

Select the contribution value of each group by selecting relevant group structure buttons. I.e. if the compound contains alkane groups click the Alkane/Oelfin/Alkyne button.

Once the button is selected a form will be displayed showing all the groups available. For each group enter the number of times it appears in the compound, in the associated text box .i.e. if the compound has two methyl groups enter a 2 in the associated text box. Click the okay button of each form to enter the contribution value of the groups for the compound.

For the Extra contribution value follow these rules to calculate its value :

Add an extra contribution value of 18.84 for any carbon group which fulfils the following criterion :

A carbon group which is joined by a single bond to a carbon group connected by a double or triple bond with a third carbon group.

A value of 18.84 should be added each time the above criterion is fulfil.

Exceptions to the rule are :

Once all the contributions have been entered, enter the molecular weight of the compound and then click the Calculate button. The predicted Specific heat capacity value for the compound will be calculated.

Example : compound : chlorobutadiene


Structure : CH2 = C – CH = CH2

CI



Group Contribution No. of groups Extra Contr. Total

=CH2 21.77 2 43.54

=C-- 15.91 1 18.84 34.75

= CH 21.35 1 18.84 40.19

--CI 36.01 1 36.01


Total Contribution 154.49

KJ/Kmol oC

Mol. Weight of compound = 88.5

Hence predicted Specific heat capacity = 154.49/88.4 KJ/Kg oC

Below is an example of the structure forms where the information about the components structure is entered into. Once the Okay button is pressed the information is placed to the Pred. Of Liquid Heat Cap. form.:-