All the octahedral complexes formed by Ni2+ are sp3d2 hybridized and not d2sp3. Why?
Answer:
To form d2sp3 hybridisation the central metal atom must have two of its inner d-orbital vacant for hybridisation. Ni2+ is 3d8 and hence even if all the electrons in the 3d sub-shell get paired due to presence of strong field ligand, it will have only one of its inner d-orbital vacant. So, Ni2+ cannot form octahedral complexes with d2sp3 hybridisation.
Which carbonyl compound having molecular formula C3H6O exists in equilibrium with an optically active compound in presence methyl alcohol?
Answer:
The carbonyl compound is propanal.
Which one among HClO, HClO2, HClO3 and HClO4 does not undergo disproportionation?
Answer:
Disproportionation is the process in which an element undergoes both oxidation and reduction in a reaction. Moreover, an element can show a maximum oxidation state equal to its “group number” and a minimum oxidation state equal to its “group number – 8”. Among the oxyacids of chlorine given, in HClO4 chlorine is in its highest oxidation state (+7). So, it cannot undergo further oxidation and hence HClO4 cannot undergo dispropotionation.
Both 2-iodopentane and 3-iodopentane are formed as products when aqueous hydroiodic acid is treated with pent-2-ene. Which one of the two products is formed in major amounts?
Answer:
2-iodopentane is formed in major amounts because the carbocation intermediate leading to the formation of 2-iodopentane is more stable than that leading to 3-iodopentane.
According to Lewis Theory of Acids and Bases, an electron pair donor is termed a base and an electron pair acceptor is termed an acid. Higher the electronegativity, lower will be the tendency for an atom to donate its un-shared pair of electrons. It is observed that phosphine (PH3) is less basic than ammonia (NH3) in spite of the fact that N is more electronegative than P. Why?
Answer:
The bond angle is PH3 is close to 90o which indicates that three of the hybrid orbital forming bonds with hydrogen atom have become almost identical to pure p-orbital and the lone pair has almost become spherical and now resembles an s-orbital. As the electron density in the s-orbital is close to the nucleus, it is difficult to distort or withdraw electron density from an s-orbital. However in NH3, the lone pair still is a sp3 orbital and electron density in it can easily be distorted or withdrawn compared to an s-orbital. So, PH3 is less basic than NH3.
Out of the following two compounds (1) and (2) respectively, which one has the most acidic alpha-hydrogen and why?
Answer:
The second one will be more stable, because after the removal of the alpha-hydrogen, the five membered ring becomes aromatic and hence becomes more stable. So, (2) has the most acidic alpha-hydrogen compared to that of (1).
Rex, a Crime Scene Investigator was summoned at the crime scene early in the morning. The victim of the homicide was lying in the middle of the living room of his house with a bullet hole on his forehead. The floor on which he was lying was clean and there were no traces of blood. The glass window was broken indicating either a forced entry or exit. “It could be the killer”, he thought. He saw some blood on the broken glass. He opened his kit and wore his latex gloves while observing the path between the victim and the window. “If the killer was injured during the forced entry, there should be blood on the floor, which was absent. May be the killer cleaned it before leaving”, he thought. “Lights”, he said while signalling his partner to turn them down and took out a bottle and started spraying Luminol, the liquid in the bottle, on the path between the window and the victim. A blue colour formation indicated the presence of blood prior to the cleaning. “Blood!” he said adding, “could be of the victim or of the killer”.
This is a normal routine for Rex. He has sprayed litres of Luminol in his career to identify blood stains. Luminol is commonly used by forensic investigators to identify even trace amounts of blood left at crime scenes as iron found in haemoglobin reacts with it. It is known to be used for this purpose from the late 1930s. Luminol is highly reactive with iron in blood and can even identify old stains in almost any surface.
The Structure of Luminol
Luminol in the correct reaction condition exhibits a phenomenon called chemiluminescence, which is the emission of light as a result of a chemical reaction. In a typical case of chemiluminescence, the reactants react to give a product in a high energy state which then returns back to the ground state or low energy state emitting light.
P + Q ® [PQ]* ® PQ + light
In presence of an oxidizing agent, usually Hydrogen Peroxide (H2O2), Luminol, shows chemiluminescence. H2O2 decomposes to form H2O and O2 and this reaction happens faster in presence of a catalyst. During forensic analysis, the catalyst is iron present in haemoglobin.
H2O2 ® H2O + O2
Under basic conditions Luminol reacts with the O2 produced by the decomposition of H2O2 and thereafter undergoes a series of transformation finally leading to a stable product along with the emission of light.
The Luminol Reaction
The action of Luminol is through a chemical reaction and oxidising agents other than iron can also make Luminol show chemiluminescence. Another aspect of Luminol reaction is that it emits light of different intensities with different substances and hence can be useful in differentiating the source of oxidising agent.
Getting back to Rex, he has now successfully solved the crime and is returning back home to catch some winks before he is summoned to another crime scene.
If the rate of a particular chemical reaction is doubled by a 10° raise in temperature, by what factor will the rate of the reaction increase with a 100° raise in temperature?
Answer:
For every 10° raise in temperature the rate of the chemical reaction is doubled, so for a 100° raise in temperature the rate should increase by (2 ^ 10) times i.e. 1024 times.
(+)-Mandelic acid has a specific rotation of +158°. What would be the specific rotation of a mixture of 25% (+)-Mandelic acid and 75% (-)-Mandelic acid?
Answer:
If the Specific rotation of (+)-Mandelic Acid is +158°, then the specific rotation of (-)-Mandelic Acid would be -158°. So a mixture of 25% (+)-Mandelic acid and 75% (-)-Mandelic acid should have a specific rotation of [0.25*(+158)]+[0.75*(-158)] = -79°.
Out of acetate ion and hydroxide ion, which one is a strong base and why?
Answer:
The conjugate base of a strong acid will be weak. Acetate ion is the conjugate base of Acetic Acid and Hydroxide ion is the conjugate base of Water. Acetic acid is a stronger acid compared to water and so, acetate ion is a weaker conjugate base compared to hydroxide ion.
alpha-Terpinene is a natural oil isolated from turpentine as well as from oil of marjorum and other sources. Its formula is C10H16. It can be hydrogenated over a palladium catalyst and absorbs two molecules of hydrogen per molecule of alpha-Terpinene to yield a new hydrocarbon, C10H20.
How many degrees of unsaturation does alpha-Terpinene possess and out of them how many are double bonds and how many are rings?
Answer:
A saturated hydrocarbon has the molecular formula of CnH2n+2.
For a saturated hydrocarbon having 10 Carbon atoms, 22 Hydrogen atoms are required to make it saturated. The molecular formula of the compound is C10H16 which means it is unsaturated and the degree of unsaturation is equivalent to 3 molecules of Hydrogen.
The molecule absorbing two molecules of Hydrogen per molecule of it shows the presence of two double bonds, and so the other degree of unsaturation must be due to a ring.
Hence, alpha-terpinene has 3 degrees of unsaturation with 1 ring and 2 double bonds.
What volume of 1M NaOH is required to completely neutralize a solution of oleum that is labeled 109% H2SO4?
Answer:
109% oleum means that 9g of H2O is required to convert all SO3 present in 100g of it to H2SO4.
The following equation shows that, 1 mole (80g) of SO3 reacts with 1 mole (18g) of H2O and hence 40g of SO3 will react with 9g of H2O.
SO3 + H2O = H2SO4
According to the following equations, 80g of NaOH will react with 80g and 98g of SO3 and H2SO4 respectively.
SO3 + 2NaOH = Na2SO4 + H2O
H2SO4 + 2NaOH = Na2SO4 + 2H2O
Weight of SO3 present in 100g of the oleum sample = 40g
Weight of H2SO4 present in 100g of the oleum sample = (100 – 40)g = 60g
Weight of NaOH required to completely neutralize 40g of SO3 = (80*40)/80 = 40g
Weight of NaOH required to completely neutralize 60g of H2SO4 = (80*60)/98 = 48.98g
Total weight of NaOH required for complete neutralization = 40 + 48.98 = 88.98g
Volume of 1M NaOH solution containing 88.98g of NaOH = (1000*88.98)/40 = 2224.5mL