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Total Categories: 6
Triuranium octoxide is commonly identified by which mineral name?
Answer: True
Triuranium octoxide is frequently referred to by the mineral name Pitchblende, alongside other designations such as Uranium(V,VI) oxide and C.I. 77919.
What is the precise chemical formula for Triuranium octoxide?
Answer: True
The precise chemical formula for Triuranium octoxide is U₃O₈.
What is the established molar mass of Triuranium octoxide?
Answer: True
The established molar mass of Triuranium octoxide is 842.08 grams per mole.
What is the solubility of Triuranium octoxide in water?
Answer: False
Triuranium octoxide exhibits negligible solubility in water; it does not dissolve when mixed with water.
Triuranium octoxide is soluble in which common mineral acids?
Answer: False
Triuranium octoxide is soluble in nitric acid and sulfuric acid, but not hydrochloric acid according to the provided information.
What is the approximate concentration of Triuranium octoxide found within the mineral pitchblende?
Answer: False
Triuranium octoxide is found in the mineral pitchblende in concentrations typically ranging from 0.01% to 0.05%, not exceeding 1%.
What is the Chemical Abstracts Service (CAS) Registry Number assigned to Triuranium octoxide?
Answer: 1344-59-8
The CAS Registry Number assigned to Triuranium octoxide is 1344-59-8.
Which of the following is not recognized as an alternative name or common designation for Triuranium octoxide?
Answer: Uranium trioxide
While Uranium(V,VI) oxide, Pitchblende, and C.I. 77919 are listed as alternative names or designations, Uranium trioxide is a distinct chemical compound and not an alternative name for U₃O₈.
What is the reported density of Triuranium octoxide?
Answer: 8.38 g/cm³
The reported density of Triuranium octoxide is 8.38 grams per cubic centimeter (g/cm³).
In which common mineral acids does Triuranium octoxide exhibit solubility?
Answer: Sulfuric acid
Triuranium octoxide exhibits solubility in nitric acid and sulfuric acid.
What is the approximate concentration of Triuranium octoxide typically found within the mineral pitchblende?
Answer: 0.01-0.05%
Triuranium octoxide is found in the mineral pitchblende in concentrations typically ranging from 0.01% to 0.05%.
Within which navigational box (Navbox) is Triuranium octoxide categorized under the U(V,VI) oxidation state group?
Answer: Uranium compounds
Triuranium octoxide is classified under the U(V,VI) oxidation state group within the 'Uranium compounds' Navbox.
What phase transition occurs for Triuranium octoxide when heated to 1,150 °C?
Answer: It melts.
Upon heating to 1,150 °C, Triuranium octoxide undergoes melting.
What is the precise chemical formula for Triuranium octoxide?
Answer: U₃O₈
The precise chemical formula for Triuranium octoxide is U₃O₈.
How is Triuranium octoxide typically described in terms of its physical state and appearance?
Answer: False
Triuranium octoxide is characterized as an olive green to black, odorless solid, not a colorless gas.
How many distinct polymorphs of Triuranium octoxide are identified in the source material?
Answer: True
The source material identifies four distinct polymorphs of Triuranium octoxide: α-U₃O₈, β-U₃O₈, γ-U₃O₈, and a high-pressure phase exhibiting a fluorite structure.
What is the crystal structure of α-U₃O₈ at room temperature?
Answer: False
At room temperature, α-U₃O₈ exhibits an orthorhombic pseudo-hexagonal crystal structure, not a hexagonal one.
Describe the process by which the β-U₃O₈ polymorph is formed.
Answer: True
The β-U₃O₈ polymorph is formed through the thermal treatment of the α-form: heating it to 1350°C followed by a slow cooling process.
What are the molecular geometries of the uranium atoms within the β-U₃O₈ polymorph?
Answer: False
In the β-U₃O₈ polymorph, not all uranium atoms exhibit tetragonal bipyramidal geometry; two uranium atoms possess pentagonal bipyramidal geometries, while the third has a tetragonal bipyramidal geometry.
Under what pressure conditions does the high-pressure fluorite-type phase of U₃O₈ form?
Answer: False
The high-pressure fluorite-type phase of U₃O₈ forms at pressures exceeding 8.1 GPa, not below 1 GPa.
What is the typical appearance of Triuranium octoxide?
Answer: Olive green to black solid
Triuranium octoxide is typically described as an olive green to black, odorless solid.
What is the characteristic molecular geometry of uranium atoms within the α-U₃O₈ polymorph?
Answer: Pentagonal bipyramidal
Within the α-U₃O₈ polymorph, each uranium atom exhibits a pentagonal bipyramidal molecular geometry, resulting from its bonding with seven oxygen atoms.
What is the crystal system classification for α-U₃O₈ at ambient temperature?
Answer: Orthorhombic pseudo-hexagonal
At room temperature, α-U₃O₈ is described as having an orthorhombic pseudo-hexagonal crystal system.
What are the defining characteristics of the high-pressure fluorite-type phase of U₃O₈?
Answer: Hyperstoichiometric fluorite structure and high density
The high-pressure fluorite-type phase of U₃O₈ is characterized by a hyperstoichiometric fluorite-type structure, high density (28% greater than α-U₃O₈), and formation at pressures exceeding 8.1 GPa.
Which polymorph of U₃O₈ is characterized by adjacent layers possessing different structural arrangements?
Answer: β-U₃O₈
The β-U₃O₈ polymorph is distinguished by having adjacent layers with differing structural arrangements, unlike the consistent layering found in α-U₃O₈.
What is the standard molar entropy (S°₂₉₈) of Triuranium octoxide?
Answer: True
The standard molar entropy of Triuranium octoxide, denoted as S°₂₉₈, is 282 Joules per mole per Kelvin (J·mol⁻¹·K⁻¹).
What is noted regarding the long-term stability of Triuranium octoxide in geologic environments?
Answer: True
Triuranium octoxide exhibits potential long-term stability in geologic environments, indicating its suitability as a durable compound for storage or disposal.
Which polymorph of Triuranium octoxide is recognized as the most stable under standard conditions?
Answer: True
The α-U₃O₈ polymorph is recognized as the most stable form of Triuranium octoxide under standard conditions.
Is the standard enthalpy of formation for Triuranium octoxide positive or negative?
Answer: False
The standard enthalpy of formation for Triuranium octoxide is a negative value (-3575 kJ·mol⁻¹), indicating an exothermic formation process.
What is the standard enthalpy of formation (ΔfH°₂₉₈) for Triuranium octoxide?
Answer: -3575 kJ·mol⁻¹
The standard enthalpy of formation (ΔfH°₂₉₈) for Triuranium octoxide is -3575 kJ·mol⁻¹.
Which polymorph of Triuranium octoxide is recognized as the most stable under standard conditions?
Answer: α-U₃O₈
The α-U₃O₈ polymorph is recognized as the most stable form of Triuranium octoxide under standard conditions.
What is the standard molar entropy (S°₂₉₈) value for Triuranium octoxide?
Answer: 282 J·mol⁻¹·K⁻¹
The standard molar entropy (S°₂₉₈) of Triuranium octoxide is reported as 282 J·mol⁻¹·K⁻¹.
Identify a common precursor compound used in the industrial production of Triuranium octoxide.
Answer: True
Ammonium diuranate is recognized as a common precursor compound for the industrial production of Triuranium octoxide, alongside ammonium uranyl carbonate.
What is the principal objective of converting Triuranium octoxide into uranium hexafluoride (UF₆)?
Answer: True
The conversion of Triuranium octoxide into uranium hexafluoride (UF₆) is a critical step undertaken to facilitate uranium enrichment, essential for the preparation of nuclear fuel.
In the context of uranium processing, Triuranium octoxide is commonly encountered as a form of:
Answer: Yellowcake
Triuranium octoxide is frequently encountered as a component of yellowcake, an intermediate product in uranium processing that is transported between mills and refineries.
Identify a common precursor compound utilized in the industrial synthesis of Triuranium octoxide.
Answer: Ammonium uranyl carbonate
Ammonium uranyl carbonate is a common precursor compound used in the industrial production of Triuranium octoxide, alongside ammonium diuranate.
What is the principal objective of converting Triuranium octoxide into uranium hexafluoride (UF₆)?
Answer: For uranium enrichment
The principal objective of converting Triuranium octoxide into uranium hexafluoride (UF₆) is to facilitate uranium enrichment, a crucial stage in the production of nuclear fuel.
What is the initial processing step for Triuranium octoxide in the 'dry' method of uranium hexafluoride production?
Answer: Purification through calcination and crushing
The initial step for Triuranium octoxide in the 'dry' process for uranium hexafluoride production involves purification through calcination and subsequent crushing.
Triuranium octoxide's stability makes it suitable for the disposal of which uranium enrichment byproduct?
Answer: Depleted uranium
Due to its inherent stability, Triuranium octoxide is utilized for the disposal of depleted uranium, a byproduct generated during the uranium enrichment process.
For what analytical purpose does Triuranium octoxide function as a certified reference material in uranium samples?
Answer: Impurity levels
Triuranium octoxide serves as a certified reference material primarily for the determination of impurity levels within uranium samples.
Under what atmospheric condition is uranium dioxide (UO₂) oxidized to Triuranium octoxide (U₃O₈)?
Answer: False
Uranium dioxide (UO₂) is oxidized to Triuranium octoxide (U₃O₈) in the presence of oxygen (O₂), not nitrogen gas.
How is Triuranium octoxide industrially produced from uranium trioxide (UO₃)?
Answer: True
Industrially, Triuranium octoxide is produced when uranium trioxide (UO₃) is heated above 500 °C, causing it to lose oxygen and form U₃O₈.
What is the initial step in the 'wet' process for producing uranium hexafluoride from Triuranium octoxide?
Answer: False
The 'wet' process for producing uranium hexafluoride from Triuranium octoxide begins with dissolving U₃O₈ in nitric acid, not sulfuric acid, to form uranyl nitrate.
By what reducing agent is Triuranium octoxide converted to uranium dioxide (UO₂)?
Answer: False
Triuranium octoxide is reduced to uranium dioxide (UO₂) by reacting it with hydrogen gas, not oxygen gas.
What transformation occurs to Triuranium octoxide when subjected to temperatures exceeding 800°C?
Answer: False
When heated above 800°C, Triuranium octoxide undergoes a reversible transformation, losing oxygen to form a non-stoichiometric compound (U₃O₈-z).
What is the primary product formed when Triuranium octoxide reacts with hydrofluoric acid at 250°C?
Answer: False
At 250°C, Triuranium octoxide reacts with hydrofluoric acid to form uranyl fluoride (UO₂F₂), not uranium tetrafluoride (UF₄).
What reagents can be used to synthesize uranyl chloride from Triuranium octoxide?
Answer: True
Uranyl chloride can be synthesized by reacting Triuranium octoxide with a combination of hydrochloric acid and hydrogen peroxide.
At what specific temperature does Triuranium octoxide decompose into uranium dioxide (UO₂)?
Answer: True
Triuranium octoxide decomposes into uranium dioxide (UO₂) upon heating to 1,300 °C.
At what specific temperature does Triuranium octoxide decompose into uranium dioxide (UO₂)?
Answer: 1300 °C
Triuranium octoxide decomposes into uranium dioxide (UO₂) upon heating to 1,300 °C.
What intermediate uranium oxides are formed during the oxidation of uranium dioxide (UO₂) to Triuranium octoxide (U₃O₈)?
Answer: U₄O₉ and U₃O₇
The oxidation of uranium dioxide (UO₂) to Triuranium octoxide (U₃O₈) proceeds through intermediate oxides, specifically U₄O₉ and U₃O₇.
What methods are employed for the reduction of uranium trioxide (UO₃) to Triuranium octoxide (U₃O₈)?
Answer: By reacting it with hydrogen gas between 500 °C and 700 °C
Uranium trioxide (UO₃) can be reduced to Triuranium octoxide (U₃O₈) via calcination at elevated temperatures or through reaction with hydrogen gas within the temperature range of 500°C to 700°C.
Following the reduction of uranium oxides to uranium dioxide (UO₂), what intermediate compound is formed upon reaction with hydrofluoric acid (HF) en route to uranium hexafluoride (UF₆)?
Answer: Uranium tetrafluoride (UF₄)
Upon reaction with hydrofluoric acid (HF), uranium dioxide (UO₂) forms uranium tetrafluoride (UF₄) as an intermediate compound in the process leading to uranium hexafluoride (UF₆).
What transformation occurs to Triuranium octoxide when subjected to temperatures exceeding 800°C?
Answer: It forms a non-stoichiometric compound (U₃O₈-z) by losing oxygen.
When heated above 800°C, Triuranium octoxide undergoes a reversible transformation, losing oxygen to form a non-stoichiometric compound (U₃O₈-z).
What is the designated GHS signal word for Triuranium octoxide?
Answer: False
Under the Globally Harmonized System (GHS) of Classification and Labelling of Chemicals, the signal word associated with Triuranium octoxide is 'Danger', not 'Warning'.
What type of radioactive emission is characteristic of Triuranium octoxide?
Answer: False
Triuranium octoxide is radioactive, but it primarily emits alpha particles, not beta particles.
What are the primary health classifications and routes of toxicity for Triuranium octoxide?
Answer: True
Triuranium octoxide is classified as a carcinogen and is demonstrably toxic via inhalation and ingestion. It poses risks of irritation to skin and eyes, and prolonged or repeated exposure can affect organs such as the kidneys, liver, lungs, and brain.
Which GHS pictograms are associated with Triuranium octoxide, indicating its toxicity and environmental impact?
Answer: True
The GHS pictograms associated with Triuranium octoxide include the skull and crossbones, signifying acute toxicity, and the dead tree/fish symbol, indicating an environmental hazard.
Which GHS hazard statement specifically denotes that Triuranium octoxide is fatal if inhaled?
Answer: H330
The GHS hazard statement H330 indicates that Triuranium octoxide is fatal if inhaled.
What are the principal health hazards associated with Triuranium octoxide?
Answer: Is a carcinogen and toxic by inhalation/ingestion
Primary health hazards associated with Triuranium octoxide include its classification as a carcinogen and its toxicity upon inhalation and ingestion, with potential for organ damage and irritation.
Which GHS pictogram is specifically associated with the health hazards of Triuranium octoxide?
Answer: Health hazard silhouette
The GHS pictogram representing a health hazard silhouette is associated with Triuranium octoxide.