Answer:
M1 = 49.04 g/mol
Explanation:
The pure benzonitrile has freezing point -12.8°C. By adding a nonvolatile compound, the freezing point will be changed, a process called cryoscopy. The freezing point will be reduced. In this case, the new freezing point is -13.4°C. The variation at the temperature can be calculated by the equation:
ΔT = Kc*W*i
Where ΔT is the variation at the freezing temperature (without the solute less with the solute), Kc is the cryoscopy constant (5.34 for benzonitrile), W is the molality, and i the Van't Hoff correction factor, which is 1 for benzonitrile.
((-12.8-(-13.4)) = 5.34*W
5.34W = 0.6
W = 0.1124 mol/kg
W = m1/M1*m2
Where m1 is the mass of the solute (in g), M1 is the molar mass of the solute (in g/mol), and m2 is the mass of the solvent (in kg).
m1 = 0.551 g, m2 = 0.1 kg
0.1124 = 0.551/M1*0.1
0.01124M1 = 0.551
M1 = 49.04 g/mol
Answer:
9.93
Explanation:
Your value for Kw is incorrect. The correct value is 5.48 × 10^-14.
pH + pOH = pKw
3.30 + pOH = -log(5.84 × 10^-14) = 13.23
pOH = 13.23 - 3.30 = 9.93
The pOH of the solution is 9.93.
Option 2, Br. I'll go over why all other three options are incorrect.
Option 1 - Krypton is a Noble gas, and so it doesn't need to accept electrons since it has an octet.
Option 3 and 4 - Both Calcium and Barium are alkaline earth metals, and give away electrons, since they only have 2.
-T.B.
