Textbook Problem 4D.1

[Tracy Tran 3L]

Carbon disulfide can be prepared from coke and elemental sulfur:

4C(s)+S8(s) --> 4CS2(l) deltaH=+358.8kJ

(b) Calculate the heat absorbed in the reaction of 197g of carbon with an excess of sulfur.

What is the significance of knowing that carbon is the limiting reactant here? How does knowing this information help me solve this question?

[Mari Masunaga 1G]

I think knowing that carbon is the limiting reactant lets you know that all 197g of it will be used up in the reaction. If sulfur were the limiting reactant then it could be possible that not all 197g of carbon would be used. hope this helps.

[Kaitlin Eblen 1I]

I agree with Mari. The same concept is used in 4D.3 when we are told that "1.40 g of carbon monoxide [reacts] with excess water vapor". Basically, the question is telling us that it is OK to use 1.4 g CO to calculate the amount of heat released per mole of CO and that we don't need to worry about masses of the reactant.