[u0625552]

q. Suppose 30.4 g of ClF3(g) and 22.8 g of Li(s) are mixed and allowed to react at atmospheric pressure and 25 C until one of the reactants is used up, producing LiCl(s) and LiF(s). Using the NIST value for the enthalpy of formation of ClF3 (webbook.nist.gov), calculate the enthalpy change for this reaction, keeping in mind that this is a negative number for an exothermic process.

What I did was write a balance equation for the reaction. ClF3+ 4Li---> 3LiF+LiCl. Then I figured out the limiting reactant of the equation. Then I found the Standard Enthalpies of Formation or LiCl and LiF. What do I do from there. I'm stuck.

[Yggdrasil]

You would also need the standard enthalpy of formation of ClF₃ in order to calculate the enthalpy change for the reaction.  You would use Hess's Law to do this calculation.