Posted by John on .
A mixture of 2.0 mol H2 and 1.0 mol of O2 is placed in a sealed evacuated container made of a perfect insulating material at 28C. The mixture is ignited with a spark and it reacts to form liquid water. What is the final temperature of the water
2H2 + O2 ==> 2H2O
2 moles H2 and 1 mol O2 will form 2 moles H2O or 2*18.015 grams. I looked up delta Ho in my text and found that it releases 187.8 kJ/mol which will be 375,600 J/ 2 moles or 36.03 grams H2O.
375,600 = mass water x specific heat water x (Tfinal-Tinitial).
Solve for Tf. Check my thinking. When you finish (be prepared for a shock), check your work and see if
mass water x specific heat water (Tf-28) = the heat released.
I presume that we neglect that this temperature should vaporize the water.