Question

Using the data in Appendix G, calculate the standard enthalpy change for each of the following reactions:

a) Si(s)+2F₂(g)→SiF₄(g)
b) 2C(s)+2H₂(g)+O₂(g)→CH₃C0₂H(l)
c) CH₄(g)+N₂(g)→HCN(g)+NH₃(g)
d) CS₂(g)+3CI₂(g)→CCI₄(g)+S₂CL₂(g)

Answer 1

To calculate the standard enthalpy change for each reaction given in Appendix G, you can use bond enthalpies to calculate the difference between the bonds broken and the bonds formed. For example, in reaction (a) Si(s) + 2F2(g) → SiF4(g), you would calculate the difference between the bond enthalpies of the bonds broken and bonds formed in the reaction.

Step-by-step explanation:

a) Si(s) + 2F2(g) → SiF4(g):

The standard enthalpy change for this reaction can be calculated using the bond enthalpies of the bonds broken and formed. The bond enthalpy values for Si-F, F-F, and Si-Si are given in Appendix G. The reaction involves breaking two F-F bonds and forming four Si-F bonds:

(Bond enthalpy of F-F x 2) - (Bond enthalpy of Si-F x 4) = Standard enthalpy change

b) 2C(s) + 2H2(g) + O2(g) → CH3CO2H(l):

This reaction involves breaking two C-C bonds, four C-H bonds, and one O=O bond, and forming two C=O bonds, two O-H bonds, and six C-H bonds:

(Bond enthalpy of C-C x 2) + (Bond enthalpy of C-H x 4) + (Bond enthalpy of O=O x 1) - (Bond enthalpy of C=O x 2) - (Bond enthalpy of O-H x 2) - (Bond enthalpy of C-H x 6) = Standard enthalpy change