We Chemist

What are non-aqueous solvents?

noreply@blogger.com (Debendra Subedi) — Sun, 28 Jun 2020 01:43:00 +0545

The solvent is that compound which can make the matter dissolves within it. Water is a solvent which can dissolve salts and many other compounds within it up to saturated level. In scientific terminology, water is taken as aqueous (as aquatic animals, aquatic things etc). So water is taken as an Aqueous solvent. It is also recognized as a Universal solvent.

What are non-aqueous solvents?

From the above introduction about solvent. It is crystal clear that water is known as an aqueous solvent. So those solvents which are not water are called non-aqueous solvents.

Examples of other non-aqueous solvents.

Organic compounds such as Alcohol, Acetone, Ether, Benzene, Carbon Tetra Chloride etc are known as non-aqueous solvents.

Lattice Energy

noreply@blogger.com (Debendra Subedi) — Mon, 5 May 2014 14:52:00 +0545

The stability of ionic solid is measured in terms of its lattice energy. Lattice energy is defined as the energy released when one mole of an ionic crystal is formed from one mole of gaseous positive and one mole of gaseous negative ions, when these are separated from each other by infinite distance. Greater the value of lattice energy, more stability in the ionic solid.

Na⁺ (g) + Cl⁻ (g) → NaCl (s)
The lattice energy of the sodium chloride is -782 KJ/mol. The negative sign indicates that the process is exothermic and that of the system is lowered as the solid is formed.

Factors affecting lattice energy:

The force of attraction between oppositely charged ion governed by

Their Ionic Radii
The charge on the ions

It is given by the equation F= q1q2/r2

where q1 and q2 are the point charges seperated by distance r in the vacuum.

It is observed that if the radii of the ions are large, the force of attraction will be less. This is better illustrated if we compare the stability of NaCl and CsCl. The force of attraction between the large Cs⁺ions and Cl^-ions will be less than that between the smaller Na⁺ions and Cl^- ions. As a result, CsCl is less stable than NaCl. We may say that the stability of an ionic solid increase with decrease interionic distance for crystals with similar ionic charges.

The role played by the charges on the ions demonstrated if we compare the lattice energy of BaO and NaCl, since both have very similar inter nuclear distance (NaCl=281 pm and Ba=277 pm). Since Ba consist of doubly charged Ba²⁺and O^2-ions, the force of attraction is much large than that in NaCl which contains singly charged ions. Hence BaO is more stable than NaCl. The stability of ionic charge for crystal with similar inter ionic distance.

SOME LATTICE ENERGY OF COMPOUNDS

Lattice Energy of chemical compounds

Macromolecule

noreply@blogger.com (Debendra Subedi) — Sun, 27 Apr 2014 15:13:00 +0545

There are many substances especially biomolecular and synthetic polymers which have their single molecules so large that they form colloidal solution directly in the solution. These molecules are termed as macromolecules. In case of the simple molecules, the molecular weight is simply the sum of the atomic weights of the atmospresent and each molecule have molecular weight but in case of macro molecule, all molecules may not have same chain and hence molecular weight. So the molecular weight of such molecules are taken as the average of the molecular weight of different chains.

Macromolecules

According to the IUPAC standard definition macromolecules is a single molecule which is used in polymer sciences. In the solution of macromolecules high concentration may alter the reaction rate and equilibrium constant such types of effect is known as molecular crowding. Plastic, Synthetic fibers, synthetic rubber, graphene are some examples of macro-molecules.

Determination molecular weight of macromolecules :

There are several ways to determine the molecular weight of macro molecules some of them are discussed under following topics:

Magic with Chemicals

noreply@blogger.com (Debendra Subedi) — Sat, 26 Apr 2014 18:11:00 +0545

Every things what happen in this world can described by chemistry. Look some magic with chemicals in lab. Never try such types of chemical reactions in home and without safety in labs. Hope you enjoy it .

Solvent Property

noreply@blogger.com (Debendra Subedi) — Sat, 26 Apr 2014 08:50:00 +0545

Solvent property of aqueous or nonaqueous solvents are directly affected by the physical and chemical factors such as liquid range, dielectric constant, donar and aceptor property, solvent property, size of molecule etc. Some characteristics properties of solvent with governs its utility as solvent as follows:

Liquid Range: The mpt and bpt of solvent indicate the range of temperature over which it can exist in liquid state. Solvents having low mpt and high bpt have high liquid range and acts as better solvent. The solvent that are liquid in room temperature ie 25 C under one atmospheric pressure are most useful.
Dielectric Constant Value: Dielectric constant determines the ability of a solvent to dissolve ionic compounds. Solvents with high dielectric constant can easily dissolve ionic compounds. Hence with high dielectric constant are most useful.
Donar and Aceptor Property: The ability of solvent to dissolve a substance also depends on its ability to solvent cations and anions. Solution of cation involve formation of complexes in which ligand are itself solvent molecules. So the solvents should have good donar property. Aceptor property are usually manifested less specially.
Solvent Polarity: The solution of cation and anion also depends on solvent polarity. If the solvent molecule is more polar the better it is able to use its negative and positives poles to solute the cations and anions respectively. Therefore the solvent with high polarity is most useful.
Size of Solvent Molecule: For maximum ion solvent interaction the solvent molecules should have small size and both ends of it should be able to interact with ions in the same ways as water interact with cation and anion to dissolve it.

Non-Aqueous Solvent

noreply@blogger.com (Debendra Subedi) — Sat, 26 Apr 2014 08:25:00 +0545

Solvent other than water is known as non-aqueous solvent. Most chemical reactions are carried out in solvent and of course water is an ideal solvent for many substances. However some reactions can't be studied in aqueous solution rather can be studied in non-aqueous solvent such as anhydrous liquid Ammonia, liquid sulphur dioxide, liquid HF, Sulphuric Acid etc.

Some Useful Links for Non-Aqueous Solvents:

Liquid Ammonia as Solvent
Liquid Sulphur Dioxide as Solvent
Inorganic Nonaqueous solvent in Wikipedia

Borazine

noreply@blogger.com (Debendra Subedi) — Sat, 26 Apr 2014 07:42:00 +0545

Borazine is a inorganic compound containing 3-3 nitrogen and boron with 6 hydrogen atoms. Borazine is cyclic in structure having polar de-localized pie-electrons. Due to the polarity of the electrons in the structure they are highly reactive.It have aromatic smell and colorless for eyes.Sometimes borazine is also known as borazol, borazole or benzol.

Physical Properties of Borazine:

Molecular Formula: B3N3H6

Molar Mass: 80.50 g/mol

Color : Colorless

Odor :Odorless

Mpt : -58 degree C

Bpt : 161 C

Borazine is commonly known as inorganic benzene. Due to the followings reasons it is known as inorganic benzene.

Like benzene, borazine is also consists of hexagonal ring.
Like benzene, borazine also have de-localized pie-electrons with aromatic character.
Borazine also participate in addition and substitution reaction like benzene.
Physical properties of borazine benzene are also similar such as molecular weights, melting and boiling point, enthalpy of vaporization.

Re-activity of Borazine:

The only one difference between borazine and benzene is that borazine is more reactive than benzene.

In benzene, pie-electrons are completely de-localized in the ring however in borazine due to difference in electronegativity between Boron and Nitrogen the B-N bond become polar further more the pie-electrons are partially de-localized in the ring. Consequently, the borazine ring become weak and less stable hence it is more reactive than benzene.