Chemistry, 02.02.2021 04:20 Zachary429

When of a certain molecular compound X are dissolved in of benzene , the freezing point of the solution is measured to be . Calculate the molar mass of X. If you need any additional information on benzene, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to the correct number of significant digits.

Answers: 2

Show answers

Answers

Answer from: jilliynr9507

The question is incomplete. Here is the complete question.

When 2.10 g of a certain molecular compound X are dissolved in 65.0 g of benzene (C₆H₆), the freezing point of the solution is measured to be 3.5°C. Calculate the molar mass of X. If you need any additional information on benzene, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to 2 significant digits.

MM = 47.30 g/mol.

Explanation: There is a relationship between freezing point depression and molality. With this last one, is possible to calculate molar mass or molar weight of a compound.

Freezing Point Depression occurs when a solute is added to a solvent: the freezing point of the solvent decreases when a non-volatile solute is incremented.

Molality or molal concentration is a quantity of solute dissolved in a certain mass, in kg, of solvent. Its symbol is m and it's defined as

$m=\frac{moles(solute)}{kg(solvent)}$

Freezing point depression and molal are related as the following:

$\Delta T_{f}=K_{f}.m$

where

$\Delta T_{f}$ is freezing point depression of solution

$K_{f}$ is molal freezing point depression constant

m is molality

Now, to determine molar mass, first, find molality of the mixture:

$\Delta T_{f}=K_{f}.m$

$m=\frac{\Delta T_{f}}{K_{f}}$

For benzene, constant is 5.12°C/molal. Then

$m=\frac{3.5}{5.12}$

m = 0.683 molal

Second, knowing the relationship between molal and moles of solute, determine the last one:

$m=\frac{moles(solute)}{kg(solvent)}$

mol(solute)=m.kg(solvent)

mol(solute) = 0.683(0.065)

mol(solute) = 0.044 mol

The definition for Molar mass is the mass in grams of 1 mol of substance:

$n(moles)=\frac{m(g)}{MM(g/mol)}$

$MM=\frac{m}{n}$

In the mixture, there are 0.044 moles of X, so its molecular mass is

$MM=\frac{2.1}{0.044}$

MM = 47.30 g/mol

The molecular compound X has molecular mass of 47.30 g/mol.

Answer from: Quest

8 carbon atoms forming single bonds with 18 hydrogen atoms; a triple bond exists between the third and fourth carbon atom from the right

explanation:

Answer from: Quest

- aluminum and copper chloride.

- the chloride ion to separate the aluminum from the oxygen so that the aluminum can react with the copper ions (and the water molecules).

Another question on Chemistry

Chemistry, 21.06.2019 16:00

Select the correct answer. you have a nightlight plugged into an outlet in the hallway, which uses 3.5 watts when plugged in. if the house circuit provides 120.0 volts, what is the current through this bulb?

Answers: 1

Answer

Chemistry, 22.06.2019 18:50

Asample of tin (ii) chloride has a mass of 0.49 g. after heating, it has a mass of 0.41 g. what is the percent by mass of water in the hydrate? %

Answers: 1

Answer

Chemistry, 22.06.2019 19:30

Awoman's basketball has a circumference between 28.5 and 29.0 inches and a maximum weight of 20 ounces (two significant figures). what are these specifications in units of centimeters and grams?

Answers: 2

Answer

Chemistry, 22.06.2019 22:30

What three things does a balanced equation show you?

Answers: 1

Answer

You know the right answer?

When of a certain molecular compound X are dissolved in of benzene , the freezing point of the solut...

Questions