PERCENTAGE(%) PURITY OF GIVEN SAMPLES:

LLUSTRATIVE EXAMPLE (1): 200 gm of CaCO₃ sample on heating produces 11.2 liters of CO₂ (g) at STP. Calculate % purity of CaCO₃ sample?

LLUSTRATIVE EXAMPLE (2): Calculate the amount of 80 % pure NaOH sample required to react with 21.3 gm Chlorine in hot condition.

LLUSTRATIVE EXAMPLE (3): When 1.25 gm sample of Chalk is strongly heated. 0.44 gm of CO2 is produced. Calculate % purity of Chalk sample?

LLUSTRATIVE EXAMPLE (4): The Mass of 80% pure H₂SO₄ required to completely neutralize 106 gm of Na₂CO₃?

LLUSTRATIVE EXAMPLE (5): When dilute HCl is added to 5.73 gm of contaminated CaCO₃, 2.49 gm of CO₂ is obtained. Find % purity of CaCO3 sample?

LLUSTRATIVE EXAMPLE (6): A sample of impure Iron pyrite (FeS₂) when 13.9 gm heated then it produces iron (iii) oxide (Fe₂O₃) and Sulphur dioxide (SO₂). If 8.02 gm Iron (iii) oxide is obtained, what was the % purity of given sample (original-FeS₂)?

HEISENBERG'S UNCERTAINTY PRINCIPLE:

"It is not possible to determine simultaneously the exact position and exact moment of a particle as small as an electron"

ILLUSTRATIVE EXAMPLE (1): If error in position of an electron is 0.33 pm, what will be the error in its velocity? (1 pm=10^-12) 

ILLUSTRATIVE EXAMPLE (2): If H⁺ (ion) is accelerated to a final velocity of 6.62×10⁺⁶ meter per second and error in velocity is 1% then find uncertainty in position is?

ILLUSTRATIVE EXAMPLE (3): Radius of nucleus is the order of 10^-13 cm (10^-15 m) and thus on the basis of Heisenberg's uncertainty principle .show that electron cannot exist within the atomic nucleus?

SOLUTION:
ILLUSTRATIVE EXAMPLE (4): If uncertainty in position and momentum of electron  are equal then prove that uncertainty in velocity  is ...

SOLUTION:
ILLUSTRATIVE EXAMPLE (5):If uncertainty in momentum of an electron are three times of uncertainty in position then uncertainty in velocity of electron would be  

SOLUTION:
ILLUSTRATIVE EXAMPLE (6): What is the uncertainty of Photon in position of  wave length 500 A .If wave length is known to an accuracy of 1pm. 

SOLUTION:
ILLUSTRATIVE EXAMPLE (7): An electron is accelerated by (V) volt and following graph is obtained calculate the (V) voltage?

SOLUTION:
ILLUSTRATIVE EXAMPLE (8): A electron having velocity 2×10⁺⁶ m/s has uncertainty in kinetic energy is 6.62/π×10^-34 j, than calculate the uncertainty in position of electron in Anstrom .

SOLUTION:
ILLUSTRATIVE EXAMPLE (9): Two particles A and B are in motion .if the wave length associated with particle A is 5×10-⁸ m. Calculate the wave length associated with particle B if momentum is Half of A?

SOLUTION:
ILLUSTRATIVE EXAMPLE (10): If uncertainty in position of an moving electron is equal to its de Broglie wave length, then its velocity will be completely uncertain. Explain?

SOLUTION:
ILLUSTRATIVE EXAMPLE (11): If the de Broglie wave length of a particle of mass (m) is 100 times of its Velocity. Then its value in term of its mass (m) and plank constant (h) is?

DIBORANE-HYDRIDE OF BORONE-(B2H6):

INTRODUCTION:

Boranes are hydride of Boron and diborane is famous borane. It is gas and is highly inflammable in air and poisonous Diborane is used for preparing substances such as high energy fuel and propellants.

The main boranes are Nidoborane and Archanoborane.

Nidoborane (BnHn+4): Example B₂H₆, B₃H₇, and B₄H₈

Archanoborane (BnHn+6):  Example B₂H₈

Preparation of Diborane:

Boranes are hydride of Boron and diborane is famous borane. It is gas and is highly inflammable in air and poisonous Diborane is used for preparing substances such as high energy fuel and propellants.

Other Methods:

CHEMICAL PROPERTIES OF DIBORANE:

The Boranes unddergo different type of chemical reactions like oxidation, pyrolysis, Nucleophilic and electrophic  and reactions with bases such as OH^- and NH₃.

(1) Reaction with Na: Diborane reacts with sodium amalgum to form an addition product B₂H₆Na₂.

(2) Reaction with air: the reaction of diborane with oxygen is highly exothermic and due to evolution of enormous amount of heat energy it can use as industrial fuel and propellants and not use as domestic due to its poisonous nature..

(3) Thermal Stability: B₂H₆ stable only at low temperature when heated 100 to 250 degree it changes into higher hydrides and On heating to 700ºC diborane dissociates.

Note: - Formation of B₂H₂Cl₄ shows that the 2H left in B₂H₂Cl₄ are responsible for dimmer formation (Bridge bond). Diborane has only four replaceable hydrogen and with their replacement, the dimeric structure continuous to be as such. Remaining  two hydrogen when they get displaced, the dimeric structure break indicating that these two hydrogen are act as bridging hydrogen.  

(9) Reaction with Ammonia (NH₃):

(1) Diborane react with excess NH₃ at temperature to form (inorganic graphite) Boron nitride (BN) _x.while when diborane and NH₃ react in 1:2 ratios at low temperature give   Inorganic Benzene (Borazole).

(2) Diborane is electron-deficient molecule and hence it reacts with several molecules having lone pair(s) of electron like CO, ether, amines, to form complex compounds.

(3) B₂H₆ give symmetrical cleavage with respect to only large size and weak amines CO, H¯, N(CH₃)₃ , THF, PH₃, PF₃ , OEt₃ OMe₂ ,Pyridine, Thiophene ,SMe₂, Set₃ etc.

(4) In the presence of small and strong base B₂H₆ undergo unsymmetrical cleavage like NH₃, H₂N (CH₃), HN (CH₃)₂ etc

ILLUSTRATIVE EXAMPLE:

(10) Methylation of Doborane:

(1) In diborane two boron atoms and four terminal hydrogen atoms lie in one plane. While two bridge hydogen atoms (encircled ) lie smmetrically above and below the plane.

(2) Total valence electrons in B₂H₆ is 12(6 from boron 3x2) and 6 from six hydrogen atoms) and there are two B-H-B (3C-2e) bridge bonds and four B-H (2C-2e) terminal bonds.

(3) Bond energy of B-H-B bond is 441 kjpermole which greater than bond energy B-H bond (341Kjpermole) hence methylation of diborane no more than four hydrogen.

(4) In above reaction it is clearly reveal that none of the bridge hydrogen in B₂H₆  has been replaced by –CH₃ .ie in this reaction both the bridge bond remaine undissociate.

Structure of "Inorganic Benzene" /Borazole/Borazine:

Structure of Boron Nitride:

Structure of Fulelrences:

Structure of Graphite:

PHYSICAL PROPERTIES DIBORANE:

(1) Diborane is a colourless gas with a foul smell and is extremely toxic.

(2) Melting point = -164.85^oc and Boiling point = -92.59^oc

(3) It is an extremely reactive inflammable gas which burns in air with a green flame