What color does zinc oxide turn when heated?
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Yellow.
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What color does zinc oxide turn when heated?
Yellow.
What is one use of KMnO4?
As a volumetric reagent in the estimation of reducing agents such as oxalic acid and ferrous ions.
What is the stable oxidation state for the d-electron configuration 3d⁸?
+2
How does the paramagnetic character change in the 3d transition series?
It increases up to Chromium (Cr) and then decreases.
What is the process of silvering of mirrors?
It is the deposition of a thin and uniform layer of silver on a clean glass surface.
What is the reaction of ZnCl2 with H2S?
ZnCl2 + H2S → ZnS.
What causes substances to appear colored?
They absorb light of a particular wavelength and transmit light of other wavelengths.
How does lanthanide contraction affect the basic strength of hydroxides?
It increases covalent character and decreases ionic character, making La(OH)3 the most basic and Lu(OH)3 the least basic.
How is potassium manganate (K2MnO4) prepared?
By fusing pyrolusite ore with KOH or K2CO3 in the presence of atmospheric oxygen.
Why do post-lanthanide elements have high density?
Due to their small size from lanthanide contraction and increased molar mass.
How is FeCl2 prepared?
By heating Fe with 2HCl or by reducing 2FeCl3 with H2.
What is the general electronic configuration of d-block elements?
(n – 1)d¹⁻¹⁰ ns⁰,¹,².
Why is silver nitrate called lunar caustic?
Because it produces a burning sensation on contact with skin, similar to caustic soda, resulting in finely divided silver (black color).
What is the commercial process for preparing CuO from malachite?
CuCO3·Cu(OH)2 is heated to produce 2CuO, H2O, and CO2.
What color is the concentrated aqueous solution containing the complex ions of copper?
Green.
What is the reaction of KMnO4 in neutral or weakly acidic solution with MnSO4 and H2O2?
2KMnO4 + 3MnSO4 + 2H2O2 in presence of Zn or ZnO produces 5MnO2 + K2SO4 + 2H2SO4.
Why is AgO considered diamagnetic despite having a d9 configuration?
Because it actually exists as AgI [AgIII O2].
What are Misch metals and what are they used for?
Misch metals are pyrophoric alloys containing lanthanoids (90-95%) and are used in cigarette lighters, flame throwers, and tracer bullets.
What happens to CuO when heated above 1100ºC?
It decomposes into 2Cu2O and O2.
Why do s- and p-block elements typically not appear colored?
They cannot undergo d-d transitions, and the energy needed to promote s or p electrons is much greater, often in the ultraviolet region.
What is the heat of sublimation represented as in the equation?
∆H_s (Heat of sublimation).
How are d-block elements classified?
Into four series: 3d, 4d, 5d, and 6d orbitals.
What is the general electronic configuration of d-block elements?
(n – 1)d 1–10 ns 0,1,2.
Why is H2SO4 used in oxidation reactions of KMnO4 in acidic medium?
H2SO4 is used because HCl reacts with KMnO4 to produce Cl2, and HNO3 acts as an oxidizing agent.
Which elements show irregularities in their electronic configurations?
Cr, Cu, Mo, Pd, Ag, and Au.
What property makes d and f-block elements good conductors of heat and electricity?
Metallic bonding.
What is one use of ZnCl2?
Used for impregnating timber to prevent destruction by insects.
What is the physical state of ZnCl2 when anhydrous?
It is a deliquescent white solid.
What is the consequence of lanthanide contraction on atomic and ionic radii?
The atomic radii of second row transition elements are similar to those of third row transition elements due to the cancellation of size increase and decrease caused by lanthanide contraction.
What happens when ZnCl2 reacts with NaOH?
ZnCl2 + NaOH → Zn(OH)2; excess NaOH leads to Na2[Zn(OH)4].
Which actinoids have applications in nuclear reactions?
Uranium (U) and Thorium (Th).
Why does the atomic and ionic radii of transition elements decrease for the first five elements in a series?
Due to the increasing effective nuclear charge (ENC) and screening effect.
What causes the increase in paramagnetic nature up to Cr?
The number of unpaired electrons increases.
What is the color observed for a wavelength absorbed in the range of 400-435 nm?
Yellow-green.
Why do transition elements have a high enthalpy of atomization?
Due to strong interatomic attraction.
What is the use of ZnSO4 in eye lotion?
It is used in eye lotion.
What are d-block elements?
Elements where the last electron enters (n – 1)d orbitals, also known as transition elements.
What is the stable oxidation state for the d-electron configuration 3d³?
+5
What do the oxides and hydroxides of lanthanoids react with to form carbonates?
They react with CO2 to form carbonates (M2CO3).
What stable oxidation states are possible for the d-electron configuration 3d⁵?
+2, +7
What is the relationship between the color observed and the color absorbed by a compound?
The observed color is the complementary color of the color absorbed.
Why are transition metals less reactive than s-block elements?
Due to high ionization energy and existence of metallic bonding among atoms.
What happens when potassium manganate is treated with chlorine?
It is converted into permanganate (KMnO4).
What is the effect of heating K2MnO4?
It decomposes to form K2MnO4, MnO2, and O2.
How do the atomic and ionic radii of the 4d-series compare to the 3d-series?
The 4d-series has higher atomic and ionic radii than the 3d-series.
What is the thermal decomposition reaction of silver nitrate?
2 AgNO₃ → 2 AgNO₂ + O₂.
What color change occurs when KMnO4 is reduced in alkaline solution?
The color changes from purple to green and finally becomes colorless.
Why are transition metal ions like Cu+, Ag+, Zn2+, Hg2+, and Cd2+ colorless?
They have no unpaired electrons and their d-orbitals are completely filled, preventing d-d transitions.
What is the minimum oxidation state for the first five transition elements based on?
The electrons in the outermost s-subshell.
What are inner transition elements?
Elements in which additional electrons enter (n – 2)f orbitals.
What is the product of the reaction of 4 MnO4- in neutral or faintly alkaline solutions?
4 MnO4- + 2H2O + 3e- produces MnO2 + 4OH-.
What is the role of cerium salts in industrial applications?
Cerium salts are used as catalysts in petroleum cracking, in volumetric analysis, and as oxidizing agents.
How is Zinc Sulphate (ZnSO4) prepared?
Zn + dil H2SO4 → ZnSO4 + H2.
When forming cations, from which subshell are electrons removed in d-block elements?
From the outermost s-subshell instead of the penultimate d-subshell.
What is zinc oxide commonly known as?
Chinese white or philosopher’s wool.
What oxidation states do lanthanides typically exhibit?
They readily form M +3 ions and some exhibit +2 and +4 states.
What is the reaction of 7 CrO4- in acidic solutions with H2S?
7 CrO4- + 3H2S + 8H+ produces 2Cr3+ + 3S + 7H2O.
What is the oxidizing property of KMnO4 in acidic medium?
It can oxidize Fe2+ to Fe3+ and H2S to sulfur.
What happens to anhydrous copper sulfate when moistened with water?
It regains its blue color, indicating the presence of water.
Why does no precipitate form when NH4OH is added to ZnSO4 containing NH4Cl?
NH4Cl suppresses the ionization of NH4OH, resulting in insufficient OH- ions to cause precipitation.
What is the result of adding sodium thiosulfate to silver nitrate?
A white precipitate appears quickly.
What is the oxidation state of Manganese (Mn) in KMnO4?
+7.
How do transition metals react with non-metals?
They react to form binary compounds, often with oxygen, nitrogen, sulfur, and halogens.
What is the solubility behavior of FeCl3?
It dissolves in both ether and water, forming solvated monomeric species.
What are the two series of f-block elements?
Lanthanides (4f-block) and Actinides (5f-block).
What are the two complex ions in equilibrium in the reaction involving [Cu(H2O)4]Cl2?
[Cu(H2O)4]2+ and [CuCl4]2-.
What do transition metals form with other metals?
Numerous useful alloys.
What is the general electronic configuration of f-block elements?
(n-2)f⁰,²…¹⁴ (n – 1)d⁰,¹,² ns².
How does atomic volume change along a period?
Atomic volume decreases along the period.
What phenomenon do actinoids exhibit due to poor shielding effect?
Actinoid contraction.
What is the electronic configuration of Mn and its cation Mn²⁺?
Mn: [Ar] 3d⁵, 4s²; Mn²⁺: [Ar] 3d⁵.
What is the reaction of silver nitrate with iodine and water?
6 AgNO₃ + 3 I₂ + 3 H₂O → 5 AgI + AgIO₃ + 6 HNO₃ (excess).
What is the preparation method for zinc oxide from zinc and oxygen?
2Zn + O2 → 2ZnO.
What defines a diamagnetic substance?
It is weakly repelled by a magnetic field and has no unpaired electrons.
Which oxidation states can Scandium (Sc) exhibit?
+2 and +3.
Which series has greater enthalpy of atomization: 4d and 5d or 3d?
4d and 5d series.
What characterizes a paramagnetic substance?
It is weakly attracted by a magnetic field and has unpaired electrons.
What is the trend in atomic and ionic sizes in the lanthanoid series?
There is a gradual decrease in sizes, known as lanthanoid contraction.
What complexes are formed when AgCl, AgBr, and AgI are treated with sodium thiosulfate?
They form [Ag(S₂O₃)₂]⁻³ complexes.
What atomic numbers correspond to inner transition elements?
59, 95, and 102 have incomplete 4f or 5f orbitals.
What does the magnitude of ionization energies indicate?
The relative stabilities of various oxidation states of transition elements.
What is the role of FeCl3 in dyeing?
It is used as an oxidizing agent and as a mordant.
What contributes to the strong metallic bonding in transition metals?
Greater effective nuclear charge and a large number of valence electrons.
Why are half-filled and completely filled d-orbitals more stable?
They have extra stability compared to other d-orbitals.
What is a property of FeCl2 in terms of its behavior in air?
It is deliquescent in air like FeCl3.
What is the electronic configuration of actinoids?
[Rn] 5f0–14, 6d0–2, 7s2.
What is the general electronic configuration of lanthanides?
[Xe] 4f n+1 5d 0 6s 2 or [Xe] 4f n 5d 1 6s 2.
What contributes to the variable valencies of transition elements?
Incomplete d-subshell and participation of ns and (n-1)d electrons in bonding.
What happens to FeCl2 when heated above 1000ºC?
It volatilizes and the vapor density indicates the presence of Fe2Cl4.
What is the preparation method for CuSO4?
CuO + H2SO4 (dil) → CuSO4 + H2O.
What happens to the number of unpaired electrons after Chromium?
The pairing of electrons takes place, decreasing the number of unpaired electrons.
What is the general oxidation state of actinoids?
+3.
What is the electronic configuration of Fe and its cation Fe²⁺?
Fe: [Ar] 3d⁶, 4s²; Fe²⁺: [Ar] 3d⁶.
What is a common application of chromic acid?
As a cleansing agent for glassware.
Why are actinoids considered strong reducing agents?
Because they are very reactive metals.
What is the crystallization form of CuSO4?
CuSO4·5H2O.
How does the ionization energy of d-block elements compare to s- and p-block elements?
It lies in between, showing less electropositive character than s-block.
What happens to the melting point of transition metals as you move left to right in a period?
The melting point increases, reaches a maximum, and then decreases towards the end of the period.
Why is K2Cr2O7 preferred over Na2Cr2O7?
Because Na2Cr2O7 is hygroscopic while K2Cr2O7 is not.
What is the result of the reaction between Cu and dilute H2SO4?
No reaction, as Cu is below H in the electrochemical series.
How does electropositive character change among transition metals?
There is a gradual decrease in electropositive character on moving along the period.
What is the preparation method of Mn2CrO4 from chromite ore?
Chromite ore is fused with sodium carbonate in excess of air to produce Na2CrO4 and Fe2O3.
How does CuO react with dilute acids?
It readily dissolves, forming CuSO4, CuCl2, or Cu(NO3)2.
What reducing agents can be used in the silvering process?
Formaldehyde, glucose, etc.
Why is the separation of lanthanides difficult?
Because they are of almost the same size, leading to similar chemical and physical properties.
What is the electron configuration of Chromium (Cr)?
[Ar] 3d^5, 4s^1.
What phenomenon explains the similar sizes of Zirconium and Hafnium?
Lanthanoid contraction.
Why are lanthanides and actinides colored?
Due to absorption of light from f-f transitions in their partly filled f-orbitals.
What happens when silver sulfate is heated?
Ag₂SO₄ → 2 Ag + SO₂ + O₂.
What happens to zinc oxide when heated?
It becomes yellow and turns white again on cooling.
Which lanthanide ions do not show paramagnetism?
La 3+ (4f 0) and Lu 3+ (4f 14) due to no unpaired electrons.
What reduces CuO to Cu under hot conditions?
Hydrogen (H2) or carbon (C).
What do lanthanides burn in oxygen to produce?
Sesquioxides M2O3, except Ce which gives CeO3.
What elements do actinoids react with?
Oxygen, halogens, hydrogen, sulfur, and acids.
What is a similarity between hexavalent Cr and S-compounds?
Both CrO3 and SO3 are acidic.
What is the heating effect of silver nitrate at 212ºC?
2 AgNO₃ → 2 AgNO₂ + O₂.
What is produced when silver oxide reacts with hydrogen?
2 Ag + H₂O₂ → 2 Ag + O₂.
What is the product of heating CuCl·2H2O at 150ºC in the presence of HCl vapor?
Anhydrous CuCl, which is a dark brown mass.
What is the color of CuCl2·2H2O?
Emerald green.
Which lanthanides exhibit +4 oxidation states?
Ce, Pr, Nd, Tb, Dy.
How do atomic volumes of transition metals compare to s-block elements?
Atomic volumes of transition metals are smaller than those of group 1 and 2 members (s-block elements).
What type of hydrides and carbides do lanthanides form upon strong heating?
Salt-like non-stoichiometric hydrides and carbides.
Why does the atomic radius not change significantly along a transition series?
Increased nuclear charge is counterbalanced by the increased screening effect from added d-electrons.
What is formed when KMnO4 reacts with H2O2 in acidic medium?
Mn2+ and O2 are produced.
What makes studying the chemical nature of actinoids difficult?
They are radioactive.
What is the relationship between unpaired electrons in d-orbitals and melting point?
An increase in unpaired electrons leads to stronger inter-particle bonds and higher melting points.
What is the hydrated form of zinc chloride?
ZnCl2 · 2H2O.
What is the reaction to obtain anhydrous ZnCl2?
Zn + Cl2 → ZnCl2.
What happens when Fe3+ ions hydrolyze?
They form an alkaline solution that reacts with NaHCO3 to liberate CO2.
What is the preparation method for FeO?
FeO is prepared from FeC2O4 in the absence of air.
How is K2MnO4 prepared from pyrolusite ore?
2MnO2 + 4KOH + O2 produces 2K2MnO4 + 2H2O.
What color does a dilute solution of CuCl2 appear?
Blue, due to the formation of [Cu(H2O)4]2+ complex.
Which lanthanides exhibit +2 oxidation states?
Eu and Yb.
How does ionic radius change with increasing charge on the cation?
Ionic radius decreases as the charge on the cation increases.
What color change occurs when conc. HCl is added to a dilute solution of CuCl2?
The solution changes to yellow due to the formation of [CuCl4]2-.
Why is Cu+ ion not stable in an aqueous solution?
Cu2+ is much more stable than Cu+ because the negative ∆hydH for Cu2+ compensates for its large second ionization enthalpy.
What is the preparation method for Chromate and Dichromate?
Roasting FeO.Cr2O3 with Na2CO3 and O2.
How is paramagnetism expressed mathematically?
By the formula μ = n(n + 2) + B.M., where n is the number of unpaired electrons.
How can FeSO4·7H2O be prepared?
It can be prepared from scrap Fe and dilute H2SO4, or from Kipp’s waste (FeS + H2SO4).
What is the principal oxidation state of lanthanum and lanthanoids?
+3, although +4 and +2 states are also exhibited occasionally.
What reaction occurs when potassium dichromate reacts with hydrochloric acid?
It evolves chlorine gas.
What is the oxidation state change of Cr in the reaction with dilute H2SO4?
The oxidation state changes from +6 to +3.
Why is the chemistry of actinoids more complex than that of lanthanoids?
Due to a wide range of oxidation states and their radioactivity.
What is the reaction of FeCl2 when heated in steam?
3FeCl2 + 4H2O → Fe3O4 + 6HCl + H2.
What is the significance of half-filled or completely filled orbitals in ionization energies?
Ionization energies are especially large, making certain ions like Zn³⁺ not formed.
What trend is observed in the density of transition metals along a period?
Density increases along the period.
What is the formula for calculating the magnetic moment of d-block elements?
μ = n(n + 2) + B.M. (where n is the number of unpaired electrons).
How do empty, half-filled, and completely filled orbitals affect oxidation states?
They provide extra stability, influencing the stability of oxidation states.
What is the chemical reaction of ZnO with H2SO4?
ZnO + H2SO4 → ZnSO4 + H2O.
What is the reaction for the disproportionation of Cu+ in aqueous solution?
2Cu+(aq) → Cu2+(aq) + Cu(s).
What trend is observed in ionization energy values after 25 Mn in the 3d-series?
They become irregular or constant due to irregular trend of atomic size.
Which transition metals exhibit zero oxidation state in their compounds?
Nickel (Ni) and Iron (Fe) in Ni(CO)4 and Fe(CO)5.
What happens to FeSO4·7H2O upon heating?
It decomposes to form anhydrous FeSO4 and then further to Fe2O3, SO2, and SO3.
What physical properties do transition metals generally exhibit?
They are hard, ductile, malleable solids with strong metallic bonding.
What is the reaction of glucose with silver oxide?
2 Ag₂O + C₆H₁₂O₆ → 4 Ag + 2 H₂O + O₂.
What are the implications of strong metallic bonding in transition metals?
They are hard, possess high densities, and have high enthalpies for atomization.
How does the number of valency electrons affect enthalpy of atomization?
Greater number of valency electrons leads to stronger bonding and higher enthalpy of atomization.
What is the reaction that produces a white precipitate when NH4OH is added to ZnSO4?
ZnSO4 + 2NH4OH → Zn(OH)2 + (NH4)2SO4.
What happens to hydrated copper sulfate (CuSO4·5H2O) when heated?
It loses its water of crystallization and turns into anhydrous CuSO4, which is white.
What is the hydrated form of FeCl2?
FeCl2·2H2O, which can further hydrate to FeCl2·4H2O and FeCl2·6H2O.
What type of compounds do transition elements form in lower oxidation states?
Ionic compounds.
What is the color of CuSO4·3H2O?
Pale blue.
How is zinc chloride (ZnCl2) prepared from zinc oxide?
ZnO + 2HCl → ZnCl2 + H2O.
What is the result of the reaction between silver bromide and potassium bromide?
A pale yellow precipitate of AgBr forms.
What is a characteristic of all transition metals regarding their outermost shell?
They possess one or two electrons in their outermost shell, exhibiting metallic nature.
What is the effect of hydrolysis on aqueous FeSO4?
The aqueous solution is acidic due to hydrolysis, forming Fe(OH)2 and H2SO4.
What role does Fe2+ play in redox reactions?
Fe2+ acts as a reducing agent, converting to Fe3+ while reducing other species.
What properties do transition metals exhibit?
Variable oxidation states, paramagnetic behavior, catalytic properties, and formation of colored ions.
Why do transition elements have higher melting points compared to s-block elements?
Due to strong metallic bonding and unpaired d-electrons leading to covalence.
How is FeCl3 prepared?
By reacting 2 Fe(s) with 3 Cl2(g).
What is lanthanide contraction?
The decrease in atomic and ionic radii from La 57 to Lu 71 due to increased nuclear attraction.
What is the appearance of solid FeCl3?
It is almost black and sublimes at about 300ºC.
What is the basic difference in electronic configuration between transition and inner transition elements?
Transition elements have (n – 1)d 1–10 ns 1–2, while inner transition elements have (n – 2)f 1–14 (n – 1)d 0–1 ns 0–2.
Why is the ionization energy of Zn, Cd, and Hg abnormally higher?
Due to greater stability of the s-subshell.
Why does zinc have the lowest enthalpy of atomization in the 3d series?
No electrons from 3d-orbitals are involved in the formation of metallic bonds in zinc.
What is the highest oxidation state of transition metals typically found in compounds with?
Fluorine and oxygen.
Which metal in the first series of transition metals exhibits +1 oxidation state most frequently?
Copper, because it achieves a completely filled d-orbital and a stable configuration.
What happens to FeO when cooled slowly?
It disintegrates into Fe3O4 and iron.
