One mole of X contains how many molecules of X

When 240 mg of a certain molecular compound X are dissolved in 35.0 g of dibenzyl ether ((C6H5CH2)2O), the freezing point of the

DedPeter [7]

Answer: MM = 16.55 g/mol

Explanation: Freezing point depression is a phenomena that explains why adding a solute to a solvent decreases the solvent freezing point: when a substance begins to freeze, its molecules slows down and rearrange itself forming a solid. If a solute is added, the molecules from the solvent interfere in the formation of the solid. To guarantee the transformation, the solution has to cooled down even more.

Freezing point and molality concentration is related by

$\Delta T=T_{f}_{(solvent)}-T_{f}_{(solution)}=K_{f}.m$

where

ΔT is freezing point depression

$T_{f}_{(solvent)}$ and $T_{f}_{(solution)}$ are freezing point of solvent and solution, respectively

$K_{f}$ is freezing point depression constant

m is molality concentration

Dibenzyl ether is the solvent and has the following properties: $K_{f}=$ 6.27 and $T_{f}$ = 3.6°C.

Molality concentration is

$m=\frac{T_{(solvent)}-T_{(solution)}}{K_{f}}$

$m=\frac{3.6-1}{6.27}$

m = 0.415

Molality concentration is moles (n) of solute dissolved in a mass, in kilogram, of solvent.

$m=\frac{moles}{mass(kg)}$

n = m(mass of solvent in kg)

n = 0.415(0.035)

n = 0.0145

Molar mass (M) is the weight of one sample mole and can be calculated as

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

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

m in grams

Molar mass of compound X is

$M=\frac{0.24}{0.0145}$

M = 16.55

Molar mass of molecular compound X is 16.55g/mol

3 0

3 years ago

Explain why NO is more soluble in water than either N2 or O2. Fill in the following blanks.

jek_recluse [69]

Answer:

a. Larger molecular size

b. Ability to react with water

c. Polarity

d. Shorter bond length

Explanation:

Ethene is a larger molecule than oxygen and nitrogen hence it is more soluble than the both other gases .

SO2 dissolves readily in water to yield an acid solution. It is an acid anhydride.

Nitric oxide is a polar compound. It remains very much polar while nitrogen and oxygen are non polar.

Nitrogen is sp hybrized, this leads to a very short bond and does not easily interact with oxygen and nitrogen

3 0

3 years ago

At room temperature, the surface tension of water is 72.0 mJ·m–2. What is the energy required to change a spherical drop of wate

Keith_Richards [23]

It is given that the surface area of sphere is 4 π r² and its volume is (4/3 π r³)
With a diameter of 1.2 mm you have a radius of 0.6 mm so the surface area about 4.5 mm² and the volume is about 0.9 mm³
The total surface energy of the original droplet is (4.5 x 10⁻⁶ m x 72) = 3.24 x 10⁻⁴mJ
The five smaller droplets need to have the same volume as the original so:
5 V = 0.9 mm³ so the volume of smaller sphere will equal 0.18 mm³
Since this smaller volume still have volume (4/3 π r³) so r = 0.35 mm
Each of the smaller droplets has a surface are = 1.54 mm²
The surface energy of the 5 smaller droplet is then (5 x 1.54 x 10⁻⁶ m x 72) = 5.54 x 10⁻⁴ mJ
From this radius the surface energy of all smaller droplets is 5.54 x 10⁻⁴ and the difference in energy is (5.54 x 10⁻⁴) - (3.24 x 10⁻⁴) = 2.3 x 10⁻⁴ mJ
Therefore we need about 2.3 x 10⁻⁴ mJ of energy to change a spherical droplet of water of diameter 1.2 mm into 5 identical smaller droplets

5 0

3 years ago

Tris base has a molecular weight of 121 g/mol. How many grams of tris base would you need to make 250ml of a 200mM SOLUTION

STatiana [176]

Answer:

6.05 g

Explanation:

Molarity of a substance , is the number of moles present in a liter of solution .

M = n / V

M = molarity

V = volume of solution in liter ,

n = moles of solute ,

From the question ,

M = 200mM

Since,

1 mM = 10⁻³ M

M = 200 * 10⁻³ M

V = 250 mL

Since,

1 mL = 10⁻³ L

V = 250 * 10⁻³ L

The moles can be calculated , by using the above relation,

M = n / V

Putting the respective values ,

200 * 10⁻³ M = n / 250 * 10⁻³ L

n = 0.05 mol

Moles is denoted by given mass divided by the molecular mass ,

Hence ,

n = w / m

n = moles ,

w = given mass ,

m = molecular mass .

From the question ,

m = 121 g/mol

n = 0.05 mol ( calculated above )

The mass of tri base can be calculated by using the above equation ,

n = w / m

Putting the respective values ,

0.05 mol = w / 121 g/mol

w = 0.05 mol * 121 g/mol

w = 6.05 g

3 0

3 years ago

Read 2 more answers

A chemist makes up a solution by dissolving 42.0 g of Mg(NO3)2 in enough water to produce a final solution volume of 259 mL. To

Igoryamba

Answer:

The molar mass of Mg(NO₃)₂, 148.3 g/mol.

Explanation:

Step 1: Given data

Mass of Mg(NO₃)₂ (solute): 42.0 g

Volume of solution: 259 mL = 0.259 L

Step 2: Calculate the moles of solute

To calculate the moles of solute, we need to know the molar mass of Mg(NO₃)₂, 148.3 g/mol.

42.0 g × 1 mol/148.3 g = 0.283 mol

Step 3: Calculate the molarity of the solution

M = moles of solute / liters of solution

M = 0.283 mol / 0.259 L

M = 1.09 M

7 0

3 years ago