All categories

3 years ago

Why organic compounds recrystallized when produced

Chemistry

1 answer:

vazorg [7]3 years ago

6 0

Answer:

An impure compound is dissolved (the impurities must also be soluble in the solvent), to prepare a highly concentrated solution at a high temperature. ... The impure substance will crystallize in a purer form because the impurities won't crystallize yet, therefore leaving the impurities behind in the solution

You might be interested in

At constant temperature, when the volume of a gas is decreased, what happens to its pressure? Select one: a. It increases. b. It

natulia [17]

Answer:

The answer would be

a. it increases

3 0

3 years ago

a normal hemoglobin concentration in the blood is 15g/100ml of blood how many kilogram of hemoglobin are in a person who has 5.5

jok3333 [9.3K]

Using stoichiometry:

5.5 L of blood x (1000 mL/1L) x (15 g/100 mL) x (1 kg/1000 g) = 0.825 kg

4 0

3 years ago

Read 2 more answers

At 55.0 ∘C, what is the vapor pressure of a solution prepared by dissolving 78.4 g of LiF in 253 g of water? The vapor pressure

ddd [48]

Answer:

82.5 mmHg

Explanation:

The vapor pressure of a solution that contains a non-volatile solute will depend on the mole fraction of the solvent and on the vapor pressure of the pure solvent at the same temperature.

P sol= χsolvent ⋅ P∘solvent, where

Psol - the vapor pressure of the solution

χ solvent - the mole fraction of the solvent

P ∘solvent - the vapor pressure of the pure solvent

Now, the most important thing to realize here is that lithium fluoride,

LiF , a soluble ionic compound, will dissociate completely in aqueous solution to form lithium cations and fluoride anions.

LiF (aq] → Li+(aq] + F − (aq]

Notice that every mole of lithium fluoride produces one mole of lithium cations and one mole of fluoride anions.

This means that you get a total of two moles of ions for every one mole of lithium fluoride in the solution.

Use lithium fluoride's molar mass to determine how many moles would be found in the given sample

78.4g⋅ (1 mole LiF /25.94 g) = 3.022 moles LiF

This means that the solution will contain

3.022 moles LiF ⋅ (2 moles ions /1 mole LiF) = 6.044 moles ions

Now, water's mole fraction in this solution will be equal to the number of moles of water divided by the total number of moles present in the solution.

To get the number of moles of water, use its molar mass

253 g ⋅ (1 mole H 2O / 18.015 g) = 14.044 moles H 2O

This means that water's mole fraction will be

χwater = 14.044 moles / (14.044 +6.044 )moles = 0.6991

The vapor pressure of the solution will thus be

Psol= 0.6991 ⋅ 118 mmHg = 82.5 mmHg

7 0

3 years ago

The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wave

timofeeve [1]

Explanation:

It is given that,

The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wavelength 3745 nm. It means that,

$n_i=8$

$\lambda=3745\ nm$

The amount of energy change during the transition is given by :

$\Delta E=R_H[\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}]$

And

$\dfrac{hc}{\lambda}=R_H[\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}]$

Plugging all the values we get :

$\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{3745\times 10^{-9}}=2.179\times 10^{-18}[\dfrac{1}{n_f^2}-\dfrac{1}{8^2}]\\\\\dfrac{5.31\times 10^{-20}}{2.179\times 10^{-18}}=[\dfrac{1}{n_f^2}-\dfrac{1}{8^2}]\\\\0.0243=[\dfrac{1}{n_f^2}-\dfrac{1}{64}]\\\\0.0243+\dfrac{1}{64}=\dfrac{1}{n_f^2}\\\\0.039925=\dfrac{1}{n_f^2}\\\\n_f^2=25\\\\n_f=5$