In a certain experiment, 0.9000 mol of hydrogen gas reacted with 0.9000 mol of s
ID: 899062 • Letter: I
Question
In a certain experiment, 0.9000 mol of hydrogen gas reacted with 0.9000 mol of solid iodine at a constant 1 atm pressure, producing 1.8000 mol of solid hydrogen iodide and absorbing 47.45 kJ of heat in the process. Which of the following thermochemical equations correctly describes this experiment?
A) H2 (g) + I2 (s) 2 HI (s); H° = 47.45 kJ
B) H2 (g) + I2 (s) 2 HI (s); H° = 52.72 kJ
C) H2 (g) + I2 (s) 2 HI (s); H° = 47.45 kJ
D) H2 (g) + I2 (s) 2 HI (s); H° = 52.72 kJ
E) H2 (g) + I2 (s) 2 HI (s); H° = 94.90 kJ
Explanation / Answer
H2 + I2 <--> 2HI
0.9 mol of H2 + 0.9 mol of I2
1.8 mol of HI solid
ABSORBING means endothermic, menaing that dH is postitive, ignore all that have a negative sign
47.45 kJ is only for 0.9 mol of reactants, we need 1 mol
47.45 kJ --> 0.9 mol
x kJ <--- 1 mol
47.56 (1mol/0.9 mol ) = 52.72 kJ
choose B which is the only answer possible
B) H2 (g) + I2 (s) 2 HI (s); H° = 52.72 kJ