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2 years ago

A solution of 2.00 g of para-dichlorobenzene in 50.0 g

Chemistry

1 answer:

vlada-n [284]2 years ago

7 0

Answer:

151 g/mol

Explanation:

When a nonvolatile substance is added to a solvent, the freezing point of the solvent is changed, which is called cryoscopy. When temperature change can be calculated by:

ΔT = Kf*W

Where Kf is the molal freezing point constant of the solvent and W is the molality of the solution.

For cyclohexane, Kf = 20.2 °C/molal, and the freezing point is 6.4 °C, so:

6.4 - 1.05 = 20.2 * W

20.2W = 5.35

W = 0.26485 molal

The molality is:

W = m1/m2*M1

Where m1 is the mass of the solute (in g), m2 is the mass of the solvent (in kg), and M1 is the molar mass of the solute. So:

0.26485 = 2.00/0.05M1

0.0132425M1 = 2.00

M1 = 151 g/mol

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Rf value is the ratio of the distance traveled by the solute to that of the solvent front on the paper used in chromatographic separation.

From the image it is clear the distance traveled by solvent front = 7.3 cm

Distance traveled by the component -1 of the mixture = 1.4 cm

Distance traveled by the component -2 of the mixture = 3.0 cm

Distance traveled by the component -3 of the mixture = 4.5 cm

Distance traveled by the component -4 of the mixture = 6.5 cm

Rf value of component-1 = $\frac{1.4 cm}{7.3 cm} =0.192$

Rf value of component-2 = $\frac{3.0 cm}{7.3 cm} =0.410$

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Rf value of component-4 = $\frac{6.5 cm}{7.3 cm} =0.890$

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3 years ago

You observe mothballs disappearing in cabinets. What do you think is the reason for this? Do all substances behave like mothball

cricket20 [7]

Answer: Mothballs have weak intermolecular forces.

No all substances do not behave like mothballs at normal conditions. Example: benzene , chloroform

Explanation:

Sublimation is a process of converting a substance from solid state to gaseous state without the formation of liquid at constant temperature.

A substance which undergoes sublimation is called as sublimating substance.

As mothballs is made of napthalene which has weak inter molecular forces of attraction between its molecules, it directly sublimes into gaseous state without leaving any residue and is called as a sublimating substance.

Not all substances behave like mothballs at normal conditions. Example: benzene , chloroform

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3 years ago

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2 years ago

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