2 moles of a compound are allowed to react in a foam coffee cup that contains 126 grams of water. The reaction caused the tempeature of the water to rise from 21 to 24.7 degrees Celsius. What is the enthalpy of this reaction? Assume that no heat is lost to the surrounding or to the coffee cup itself.
2006-11-23 14:56:49 · 4 answers · asked by diana t 1 in Science & Mathematics ➔ Chemistry
Sounds like Q = (24.7-21)*126*1.0 = 466.2 gcal or 233.1gcal/mole
2006-11-23 15:02:14 · answer #1 · answered by Steve 7 · 1⤊ 0⤋
The answer that Steve gave is correct. The only thing I am pointing out is that some problems want the enthalpy in joules per mole instead of calories per mole.
Q = mass X specific heat X change in Celsius temp.
Q = (126 g) X (4.184 j/gC) X (24.7 - 21 Celsius)
This will give the joules for 2 moles of the substance. Divide this by the number of mole and you get the joules per mole.
2006-11-23 23:08:57 · answer #2 · answered by physandchemteach 7 · 2⤊ 0⤋
The answer that Steve gave is correct. The only thing I am pointing out is that some problems want the enthalpy in joules per mole instead of calories per mole.
Q = mass X specific heat X change in Celsius temp.
Q = (126 g) X (4.184 j/gC) X (24.7 - 21 Celsius)
This will give the joules for 2 moles of the substance. Divide this by the number of mole and you get the joules per mole.
2006-11-23 23:40:06 · answer #3 · answered by C.J. W 3 · 1⤊ 1⤋
Do your own homework.
2006-11-24 02:27:28 · answer #4 · answered by Jimmy Dean 3 · 0⤊ 0⤋