Answer:
-2.3 ºC
Explanation:
Kf (benzene) = 5.12 ° C kg mol – 1
1st - We calculate the moles of condensed gas using the ideal gas equation:
n = PV / (RT)
P = 748/760 = 0.984 atm
T = 270 + 273.15 = 543.15 K
V = 4 L
R = 0.082 atm.L / mol.K
n = (0.984atm * 4L) / (0.082atm.L / K.mol * 543.15K) = 0.088 mol
Then, you calculate the molality of the solution:
m = n / kg solvent
m = 0.088 mol / 0.058 kg = 1.52mol / kg
Then you calculate the decrease in freezing point (DT)
DT = m * Kf
DT = 1.52 * 5.12 = 7.8 ° C
Knowing that the freezing point of pure benzene is 5.5 ºC, we calculate the freezing point of the solution:
T = 5.5 - 7.8 = -2.3 ºC
They don’t, what you even on about
The ratio of reactant in grams would be influenced by the reaction equation and the molar mass of the elements. But the ratio of a reactant needed in grams would be same for a reaction.
If 2 grams of element X combine with 4 grams of element Y to form compound XY, it means the ratio of reactant in grams<span> would be 2:4 or 1:2
The number of element X needed for 28grams of element Y would be:
1/2 * 28grams = 14 grams.</span>
