When 1.47 g of an unknown non-electrolyte is dissolved in 50.0 g of carbon tetrachloride, the freezing point decreased by 7.03 degrees C. If the Kfp of the solvent is 29.8 K/m, calculate the molar mass of the unknown solute.

124.6 g/mol will be the molar mass for the unknown non-electrolyte

Explanation:

Freezing point depression →  ΔT = Kf . m

ΔT indicates the temperature variation:

Freezing point of pure solvent - Freezing point of solution

Kf is the cryoscopic constant → 29.8 K/m

Generally the unit is °C/m but we have to type the ΔT by K so let's replace the data given → 7.03 K = 29.8 K/m . m

m = 7.03 K / 29.8 m/K = 0.236 mol/kg

m means molality, the moles of solute in 1 kg of solvent. If we want to determine the moles of solute we do this operation:

molality . kg, so we may convert the mass of solvent from g to kg.

50 g . 1kg/1000g = 0.05 kg

0.236 mol/kg . 0.05 kg = 0.0118 moles

Molar mass → g/mol → So 1.47 g / 0.0118 mol = 124.6 g/mol

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j

i think its 100

i hope this !