a) A + B -> 2C, delta H 1 2C ->A + B, delta H 2 = ? Delta H 2 =? b) A calorimete
ID: 917000 • Letter: A
Question
a) A + B -> 2C, delta H1
2C ->A + B, delta H2= ?
Delta H2=?
b) A calorimeter contains 25.0 mL of water at 12.5 degrees C. When 2.30 g of X (a substance with a molar mass of 42.0 g/mol) is added, it dissolves via the reaction: X(s)+H2O(l)->X(aq), and the temperature of the solution increases to 26.0 degrees C. Caluclate the enthalpy chance, delta H, for this reaction per mole of X. Assume that the specific heat of the resuting solution is equal to that of water [4.18 J/(g*degrees C)], that the desity of water is 1.00 g/mL, and that no heat is lost to the calorimeter itself, nor to the surroundings. Express answer in kJ/mol to 3 sig figs
Explanation / Answer
a) A + B -> 2C, delta H1
2C ->A + B, delta H2= -DH1
b) No of mol of X = 2.3/42 = 0.0547 mol
qreleased = m*s*DT
mass of solution = 25*1+2.3 = 27.3 grams
specificheat of solution = 4.18 j/g.c
DT = 26-12.5 = 13.5 C
qreleased = 27.3*4.18*13.5 = 1540.54 joule.
DHrxn = -q/n = -1540.54/0.0547 = -28.16 kj/mol
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.