Using loops to fill in table

[jpe1]

Im trying to make a code to fill in a table for me. I thought about using loops to do it. However Im not sure on how to get it to do what I want. I understand the basics of loops. I think I would also use a loop to multiple the values together then select the next row down until it reads delta Hr or Delta Sr. I want the code to work if I change the number of products and reactants, however I only know how to code if the number was fixed. ie I would use activecell.offset(x,y) to select the cell and sum the values into it, but if the number of reactants and products changes this cell will also move. I have attached a spreadsheet containing the individual steps but am not sure how code for it.

[mrice]

Try

B6

=SUMPRODUCT(OFFSET(INDIRECT("A" & MATCH("Reactants",A:A,0)),0,1,COUNTIF(A:A,"Reactants"),1),OFFSET(INDIRECT("A" & MATCH("Reactants",A:A,0)),0,2,COUNTIF(A:A,"Reactants"),1))

B7
=SUMPRODUCT(OFFSET(INDIRECT("A" & MATCH("Reactants",A:A,0)),0,1,COUNTIF(A:A,"Reactants"),1),OFFSET(INDIRECT("A" & MATCH("Reactants",A:A,0)),0,3,COUNTIF(A:A,"Reactants"),1))

Similarly for products.

Hopefully this will get you started.

Couldn't see a temperature term - is this already factored into your delta S value?

[jpe1]

Thank you. How would I apply that to a general code rather than just putting it into the cells? Heres what Ive got so far:
[CODE]Sub Gibbs()
Range("c3").Select
Do Until ActiveCell.Value = "Delta Hr Reactants"
X = ActiveCell.Offset(0, 1) * ActiveCell.Offset(0, 2)
ActiveCell.Offset(1, 0).Select
Loop
ActiveCell.Offset(0, 1).Select
ActiveCell.Value = 'SUM OF X VALUES
End Sub
/[CODE]
Im not sure on how to write the part of the code that will sum the all the x values.
Also Im this code will find gibbs at a reference temp and pressure of 1atm and 298K. Because at this temp and pressure most enthalpy and entropy values are known. I can then use this with the integrated vant hoff equation to find the position of equilibrium

[mrice]

Maybe

[CODE]Sub Gibbs()
Range("c3").Select
Do Until ActiveCell.Value = "Delta Hr Reactants"
X = X + (ActiveCell.Offset(0, 1) * ActiveCell.Offset(0, 2))
ActiveCell.Offset(1, 0).Select
Loop
ActiveCell.Offset(0, 1).Select
ActiveCell.Value = X
End Sub
/[CODE]

[jpe1]

Thank you, that works prefectly