Wednesday
May 4, 2016

# Homework Help: Chemistry

Posted by Raul on Sunday, March 24, 2013 at 3:36pm.

One reaction of iron with hydrochloric acid is represented by the following
thermochemical equation.
Fe(s) + 2HCl(aq) ? FeCl2(aq) + H2(g); (Delta)H°= –87.9 kJ
How much heat is liberated at constant pressure if 0.215 g of iron reacts with 40.4 mL of
0.579 M HCl?
How much heat is liberated at constant pressure when 28 g of calcium oxide reacts with 86.5 L of carbon dioxide gas measured at 1 atm pressure and 25C( R=0.0821 L.atm\(K.mol) CaO(s)+CO2(g)---CaCO3(s);delta H=-178.3 kJ
These are final two HW problems I can not get the correct answer on either. Been waking on them for two days. Help show all steps so I can find my mistakes.
• Chemistry - DrBob222, Sunday, March 24, 2013 at 4:09pm

The better idea is for you to type and let us check. It's much faster that way. However, I'll split it with you and do the first.
mols Fe = grams/molar mass. (You need to check that Fe is the limiting reagent.(It is.)
Basically you read it this way. If 87.9 kJ heat is liberated for 1 mol (55.85) g Fe, how much is liberated for 0.215.
That's 87.9 kJ x (0.215/55.85) = ?kJ.