Examkin

Chemistry, Industry and the Environment

69 soru

Tüm türler69Çoktan seçmeli39Doğru / Yanlış7Eşleştirme15Sıralama6Boşluk doldurma2
Soru 1Soru →

Arrange the following major stages of cement manufacturing in the correct chronological sequence, from initial raw material handling to the final product stage.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence of cement production is: Extraction of limestone and clay, Crushing and blending raw meal, Heating in a rotary kiln to produce clinker, and Grinding clinker with gypsum.
Cement manufacturing begins with raw material extraction from quarries (limestone and clay). These raw materials are crushed and blended to form raw meal. The mixture is then calcined in a rotary kiln at temperatures up to 1450 °C to form clinker nodules. Finally, clinker is pulverized with a small quantity of gypsum (to retard flash setting) to produce commercial cement powder.

Adım Adım Çözüm

1
Identify raw material acquisition
Quarrying of limestone and clay occurs first.
Industrial processes must start with retrieving raw natural resources from the site.
2
Identify raw material preparation
Crushing and blending limestone and clay into raw meal occurs second.
The raw materials must be homogenized and reduced in size prior to high-temperature reaction.
3
Identify chemical transformation
Rotary kiln heating to form clinker occurs third.
High-temperature calcination converts calcium carbonate to calcium oxide, forming nodules of clinker.
4
Identify final processing and additive mixing
Grinding clinker with gypsum occurs last.
Gypsum is added at the final step to regulate the setting time of the finished cement.

Anahtar Kavram

Raw material processing sequence in cement chemical industry
Soru 2Soru →

Industrial chemical manufacturing processes are classified into heavy chemical production and fine chemical production depending on operational scale, purity requirements, and economic cost. Which of the following options correctly pairs a fine chemical with its defining production characteristic?

Cevabı ve açıklamayı göster

Cevap: Aspirin — produced in batch operations to achieve a high degree of purity

Cevap

Aspirin is a fine chemical produced in batch operations to achieve a high degree of purity.
Fine chemicals such as pharmaceuticals (e.g., aspirin), dyes, and analytical reagents are characterized by production in small batch lots under strict quality control to guarantee high purity levels.

Adım Adım Çözüm

1
Differentiate heavy chemicals from fine chemicals based on production criteria.
Heavy chemicals (H2SO4\text{H}_2\text{SO}_4, NaOH\text{NaOH}, NH3\text{NH}_3) are manufactured continuously in large tonnage (bulk) at low cost with moderate purity. Fine chemicals (pharmaceuticals, dyes, perfumes, food additives) are produced in small batch quantities with high chemical purity and high unit price.
Classification relies on understanding scale, batch versus continuous operation, and required purity level.
2
Evaluate the given choices against these criteria.
Aspirin is a pharmaceutical substance manufactured in small batches requiring precise quality control and exceptional purity, matching all criteria of a fine chemical.
Identifying the correct pair requires matching the named compound with its true industrial chemical category.

Anahtar Kavram

Distinction between Heavy Chemicals and Fine Chemicals
Tahmini Süre:1m 0s
Soru 3Soru →

Chlorofluorocarbons (CFCs) released into the atmosphere diffuse into the stratosphere, where they are decomposed by intense solar ultraviolet radiation. Which active reactive species generated during this photolysis process directly catalyzes the catalytic breakdown of ozone (O3\text{O}_3) molecules?

Cevabı ve açıklamayı göster

Cevap: Chlorine free radical (Cl∙\text{Cl}^\bullet)

Cevap

The chlorine free radical (Cl∙\text{Cl}^\bullet) released from the photolysis of chlorofluorocarbons directly catalyzes the depletion of stratospheric ozone molecules.
Under stratospheric ultraviolet (UV) irradiation, chlorofluorocarbon (CFC) molecules undergo homolytic cleavage to produce reactive chlorine free radicals (Cl∙\text{Cl}^\bullet). A chlorine radical attacks an ozone molecule (O3\text{O}_3) to form a chlorine monoxide radical (ClO∙\text{ClO}^\bullet) and a diatomic oxygen molecule (O2\text{O}_2). The chlorine monoxide radical subsequently reacts with atomic oxygen to regenerate the free chlorine radical (Cl∙\text{Cl}^\bullet). Because the radical is regenerated, it acts as a catalyst in the continuous breakdown of the protective ozone layer.

Adım Adım Çözüm

1
Identify the photolysis reaction of CFCs in the stratosphere.
Ultraviolet radiation breaks a C-Cl\text{C-Cl} bond in CFCs (e.g., CF2Cl2+hν→CF2Cl∙+Cl∙\text{CF}_2\text{Cl}_2 + h\nu \rightarrow \text{CF}_2\text{Cl}^\bullet + \text{Cl}^\bullet), releasing reactive chlorine free radicals.
High-energy UV photons possess sufficient energy to cleave the chemical bond in the tropospheric-stable CFC molecules upon reaching the stratosphere.
2
Analyze the catalytic cycle of ozone destruction.
Cl∙+O3→ClO∙+O2\text{Cl}^\bullet + \text{O}_3 \rightarrow \text{ClO}^\bullet + \text{O}_2 followed by ClO∙+O→Cl∙+O2\text{ClO}^\bullet + \text{O} \rightarrow \text{Cl}^\bullet + \text{O}_2.
The chlorine free radical acts as a true catalyst because it is regenerated at the end of the reaction cycle, allowing a single radical to destroy up to 100,000100,000 ozone molecules.
3
Distinguish between greenhouse gases and ozone-depleting catalysts.
CO2\text{CO}_2 and CH4\text{CH}_4 trap infrared heat (greenhouse effect), whereas Cl∙\text{Cl}^\bullet radicals chemically decompose ozone (ozone layer depletion).
Conflating global warming mechanisms with ozone depletion mechanisms is a common conceptual error.

Anahtar Kavram

Photolysis of CFCs and Catalytic Cycle of Ozone Layer Depletion
Soru 4Soru →
In the industrial Contact process for the manufacture of tetraoxosulfate(VI) acid, the conversion of sulfur(IV) oxide to sulfur(VI) oxide proceeds according to the thermochemical equation:
2SO2(g)+O2(g)⇌2SO3(g)ΔH=−197 kJ mol−12SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g) \quad \Delta H = -197 \text{ kJ mol}^{-1}
Although Le Chatelier's principle predicts a higher equilibrium yield of SO3(g)SO_3(g) at lower temperatures, the process is industrially operated at a compromise temperature of approximately 450∘C450^\circ\text{C} using a vanadium(V) oxide (V2O5V_2O_5) catalyst. Which of the following best explains why operating at a significantly lower temperature is commercially unviable?
Cevabı ve açıklamayı göster

Cevap: Lowering the temperature significantly reduces the kinetic energy of the reactant molecules and renders the V2O5V_2O_5 catalyst inactive, resulting in an unacceptably slow reaction rate despite the favorable equilibrium position.

Cevap

Operating at a lower temperature is commercially unviable because lowering the temperature significantly reduces the kinetic energy of reactant molecules and renders the vanadium(V) oxide catalyst inactive, making the rate of reaching equilibrium extremely slow despite a favorable equilibrium yield.
The correct explanation emphasizes the crucial distinction between chemical equilibrium (yield) and reaction rate (kinetics) in industrial chemistry. For exothermic reactions like the oxidation of SO2SO_2, decreasing temperature shifts equilibrium to the right, yielding more product. However, at lower temperatures, the rate of reaction drops exponentially, and the V2O5V_2O_5 catalyst loses its catalytic activity (which requires temperatures ≥400∘C\ge 400^\circ\text{C}). Thus, 450∘C450^\circ\text{C} is chosen as an optimum compromise temperature.

Adım Adım Çözüm

1
Analyze the thermodynamic profile of the reaction
The forward reaction 2SO2(g)+O2(g)⇌2SO3(g)2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g) is exothermic (ΔH=−197 kJ mol−1\Delta H = -197 \text{ kJ mol}^{-1}). According to Le Chatelier's principle, lowering the temperature favors the exothermic direction, increasing the equilibrium concentration of SO3SO_3.
Understanding thermodynamic equilibrium factors governing yield.
2
Analyze kinetic factor and catalyst requirements
Reaction rate depends on activation energy and temperature. At lower temperatures, fewer molecules possess energy E≥EaE \ge E_a. Furthermore, vanadium(V) oxide (V2O5V_2O_5) catalyst is only active above ∼400∘C\sim 400^\circ\text{C}.
Commercial viability requires a balance between yield (thermodynamics) and rate (kinetics).
3
Evaluate the commercial compromise
Operating at 450∘C450^\circ\text{C} provides an optimum compromise: a satisfactory rate of conversion (∼98%\sim 98\% yield) in a reasonable timeframe.
Industrial chemical processes must maximize production rate alongside conversion efficiency.

Anahtar Kavram

Compromise Conditions in Industrial Chemical Synthesis (Kinetics vs. Equilibrium Yield)
Tahmini Süre:2m 0s
Soru 5Soru →

Match each chemical industry location in Nigeria with the primary raw material or major siting factor that led to its establishment.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Cement manufacturing plant at Ewekoro
Petroleum refinery at Port Harcourt
Soap manufacturing industry at Aba
Nitrogenous fertilizer complex at Eleme

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Cement plant at Ewekoro matches Abundant local limestone deposits; Petroleum refinery at Port Harcourt matches Proximity to crude oil fields and marine transport; Soap industry at Aba matches Availability of palm oil and vegetable fats; Nitrogenous fertilizer complex at Eleme matches Natural gas feedstock for ammonia synthesis.
Each industry is paired correctly according to its fundamental chemical raw materials and industrial geography in Nigeria: cement requires limestone deposits found at Ewekoro; crude oil refining relies on coastal oilfields near Port Harcourt; soap making relies on local vegetable fats around Aba; and synthetic fertilizer manufacturing utilizes natural gas reserves at Eleme.

Adım Adım Çözüm

1
Identify the primary chemical reaction and bulk raw material required for each industry.
Cement manufacturing requires limestone (CaCO3CaCO_3); soap production requires vegetable oils/fats; petroleum refining requires crude oil; nitrogenous fertilizer synthesis requires natural gas (CH4CH_4) for hydrogen gas generation.
Chemical industries prioritize proximity to raw materials when the bulk material loses mass during processing or incurs heavy freight expenses.
2
Correlate each chemical industry with its specific geographic siting context in Nigeria.
Ewekoro has vast limestone deposits; Port Harcourt is adjacent to Niger Delta crude oil fields; Aba has access to palm oil belts; Eleme has natural gas pipeline connections.
Industrial siting decisions optimize raw material availability, power supply, transport infrastructure, and market accessibility.

Anahtar Kavram

Factors governing the siting of chemical industries and raw material misallocation.
Soru 6Soru →

Arrange the following sequential steps involved in the industrial biotechnology process of producing ethanol from starchy roots (cassava) in the correct chronological order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct chronological order of industrial ethanol production from cassava is: (1) Mashing crushed cassava roots with steam to release starch granules, (2) Adding malt containing diastase to hydrolyze starch into maltose, (3) Inoculating with yeast containing maltase and zymase to ferment sugars into ethanol, and (4) Subjecting the fermented wash to fractional distillation to isolate concentrated ethanol.
The production of industrial ethanol from cassava follows a logical sequence: raw starchy material is first physically prepared and cooked (mashing with steam), hydrolyzed by enzymes into fermentable sugars (diastase converts starch to maltose), fermented by yeast enzymes (maltase and zymase convert sugars to ethanol and carbon(IV) oxide), and finally purified by fractional distillation to collect concentrated ethanol.

Adım Adım Çözüm

1
Identify raw material physical preparation
Crushed cassava is steam-mashed to gelatinize starch and release starch granules.
Raw plant cell walls must be broken so that enzymes can interact efficiently with starch molecules.
2
Identify enzymatic breakdown of complex carbohydrate polymers
Diastase enzyme in malt breaks down starch into maltose disaccharides.
Yeast cannot directly ferment large complex starch polymers efficiently without prior hydrolysis.
3
Identify biological fermentation stage
Maltase converts maltose to glucose, and zymase ferments glucose into ethanol and CO2CO_2.
Anaerobic fermentation by enzymes in yeast yields ethanol as the major liquid metabolic product.
4
Identify final physical separation and concentration stage
Fractional distillation concentrates ethanol from the aqueous wash mixture.
Fermentation yields aqueous ethanol (about 10−15%10-15\% purity), which requires separation from water based on ethanol's lower boiling point (78.3∘C78.3^\circ\text{C}).

Anahtar Kavram

Enzymatic hydrolysis, fermentation, and purification in industrial biotechnology ethanol manufacture
Soru 7Soru →

During peak daylight hours in heavily industrialized urban areas, unburnt hydrocarbons and nitrogen oxides undergo complex atmospheric reactions catalyzed by ultraviolet light. Which of the following substances is produced as a toxic secondary pollutant in this process and serves as a major component of photochemical smog?

Cevabı ve açıklamayı göster

Cevap: Peroxyacetyl nitrate (PAN)

Cevap

Peroxyacetyl nitrate (PAN) is formed as a secondary pollutant when hydrocarbons and nitrogen oxides react in the presence of sunlight during photochemical smog formation.
Peroxyacetyl nitrate (PAN) is a classic secondary pollutant produced when volatile hydrocarbons and nitrogen dioxide react in the lower atmosphere under the influence of ultraviolet sunlight, forming a major eye-irritating constituent of photochemical smog.

Adım Adım Çözüm

1
Analyze the conditions given in the prompt.
The reaction takes place in sunlight (ultraviolet radiation) involving primary emissions of nitrogen oxides (NOxNO_x) and hydrocarbons.
Photochemical smog is driven by solar radiation acting on primary motor vehicle exhaust gases.
2
Distinguish between primary and secondary pollutants.
Primary pollutants (CO2CO_2, SO2SO_2, NONO) are emitted directly from sources, whereas secondary pollutants (such as ozone O3O_3 and peroxyacetyl nitrate) form via chemical interactions in the atmosphere.
The question requires identifying a secondary pollutant generated during light-driven reactions.
3
Identify the specific secondary product.
Peroxyacetyl nitrate (PAN) is a powerful lachrymator and phytotoxic secondary pollutant characteristic of photochemical smog.
PAN is produced when peroxyacyl radicals combine with nitrogen dioxide (NO2NO_2) under UV radiation.

Anahtar Kavram

Secondary Pollutants and Photochemical Smog
Soru 8Soru →

Match each atmospheric pollutant in Column A with its corresponding environmental impact or chemical role in Column B.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Peroxyacetyl nitrate (PAN)
Sulfur dioxide (SO2SO_2)
Carbon monoxide (COCO)
Nitrogen dioxide (NO2NO_2)

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Peroxyacetyl nitrate (PAN) matches with being a secondary pollutant in photochemical smog causing eye irritation; Sulfur dioxide (SO2SO_2) matches with being a primary precursor to acid rain via sulfuric acid formation; Carbon monoxide (COCO) matches with binding to hemoglobin to inhibit oxygen transport; Nitrogen dioxide (NO2NO_2) matches with undergoing photolysis in sunlight to form ground-level ozone.
Peroxyacetyl nitrate (PAN) is a classic secondary pollutant responsible for eye irritation in photochemical smog. Sulfur dioxide (SO2SO_2) is the main precursor to acid rain through atmospheric oxidation into sulfuric acid. Carbon monoxide (COCO) impairs oxygen transport in animals by producing carboxyhemoglobin. Nitrogen dioxide (NO2NO_2) acts as a primary trigger for tropospheric ozone (O3O_3) synthesis via solar photolysis.

Adım Adım Çözüm

1
Identify the chemical origin and effect of Peroxyacetyl nitrate (PAN)
PAN is a secondary pollutant created in photochemical smog that causes severe eye irritation.
PAN is produced when hydrocarbons react with nitrogen oxides under sunlight.
2
Identify the primary environmental damage linked to Sulfur dioxide (SO2SO_2)
SO2SO_2 dissolves in atmospheric moisture after oxidation to produce acid rain containing tetraoxosulfate(VI) acid.
SO2+H2O+12O2→H2SO4SO_2 + H_2O + \frac{1}{2}O_2 \rightarrow H_2SO_4.
3
Analyze the physiological effect of Carbon monoxide (COCO)
COCO forms carboxyhemoglobin in blood, blocking oxygen uptake.
Hemoglobin has a significantly higher affinity for COCO than for O2O_2.
4
Identify the role of Nitrogen dioxide (NO2NO_2) in smog formation
NO2NO_2 photolyzes under UV radiation to release atomic oxygen, initiating ground-level ozone (O3O_3) synthesis.
Sunlight breaks the N−ON-O bond in NO2NO_2 to drive photochemical reactions.

Anahtar Kavram

Distinction between primary and secondary air pollutants, photochemical smog reactions, and acid rain precursors.
Soru 9Soru →

Match each water treatment chemical agent or industrial pollutant on the left with its corresponding chemical function or environmental impact on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Potash alum, KAl(SO4)2⋅12H2O\text{KAl(SO}_4)_2 \cdot 12\text{H}_2\text{O}
Chlorine gas, Cl2\text{Cl}_2
Crude oil spill
Lead(II) ions, Pb2+\text{Pb}^{2+}

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Potash alum pairs with colloidal coagulation; Chlorine gas pairs with micro-organism disinfection; Crude oil spill pairs with blocking atmospheric oxygen dissolution; Lead(II) ions pair with heavy metal bioaccumulation and neurological toxicity.
Potash alum acts as a coagulating agent to settle suspended clay particles; chlorine functions as a chemical disinfectant to kill pathogens; crude oil forms a floating slick that prevents atmospheric oxygen from dissolving into water; lead ions are heavy metal pollutants that bioaccumulate in organism tissues.

Adım Adım Çözüm

1
Differentiate between physical purification agents and chemical sterilization agents used in water treatment.
Potash alum is added during coagulation to precipitate fine colloidal particles, while chlorine is added at the final stage to kill pathogens.
Coagulation removes turbidity whereas chlorination performs disinfection.
2
Analyze the mechanisms of industrial pollutants in aquatic environments.
Crude oil forms a thin physical barrier across water surfaces, reducing dissolved oxygen levels. Heavy metal ions such as Pb2+\text{Pb}^{2+} persist in ecosystems and concentrate in biological organisms.
Physical barriers cause hypoxia, whereas non-biodegradable heavy metals cause cumulative physiological toxicity.

Anahtar Kavram

Chemical mechanisms of municipal water purification agents and environmental impacts of industrial effluents
Soru 10Soru →

Agricultural soil treated continuously with synthetic pesticides often experiences long-term ecological damage. Which of the following chemical characteristics best explains why organochlorine pesticides such as DDT present a severe long-term threat to soil ecosystems and higher trophic levels?

Cevabı ve açıklamayı göster

Cevap: They resist microbial degradation due to stable carbon-chlorine bonds and bioaccumulate in the fatty tissues of organisms.

Cevap

Organochlorine pesticides like DDT resist microbial degradation due to stable carbon-chlorine bonds and bioaccumulate in the fatty tissues of organisms across the food chain.
Organochlorine pesticides such as DDT possess strong carbon-chlorine (C−ClC-Cl) bonds that resist chemical and microbial degradation in soil. Furthermore, their high fat-solubility (lipophilicity) causes them to accumulate in the fatty tissues of living organisms, leading to biomagnification across successive levels of the food chain.

Adım Adım Çözüm

1
Analyze the chemical structure and stability of organochlorine pesticides.
Organochlorines contain strong, highly stable carbon-chlorine (C−ClC-Cl) bonds that soil bacteria and fungi lack the enzymes to readily metabolize.
Chemical stability determines environmental persistence in soil.
2
Evaluate the solubility and transport mechanism of organochlorines in biological systems.
They are lipophilic (fat-soluble) and hydrophobic, meaning they store in adipose tissue rather than dissolving in water or being excreted.
Fat solubility leads to bioaccumulation and biomagnification up the food chain.

Anahtar Kavram

Pesticide Persistence and Bioaccumulation in Environmental Chemistry
Tahmini Süre:1m 0s
Soru 11Soru →

Which of the following materials is classified as non-biodegradable because soil micro-organisms cannot decompose it?

Cevabı ve açıklamayı göster

Cevap: Polyethene

Cevap

Polyethene is non-biodegradable.
Polyethene is a synthetic addition polymer. Because soil micro-organisms lack enzymes capable of breaking down its continuous carbon-carbon single bonds, it remains intact in the environment for long periods, leading to persistent pollution.

Adım Adım Çözüm

1
Classify the given substances into natural polymers and synthetic addition polymers.
Starch, cellulose, and proteins are natural polymers produced by living organisms, whereas polyethene is a synthetic addition polymer.
Biological decomposers possess specific enzymes capable of hydrolyzing the chemical linkages in natural polymers.
2
Determine biodegradability based on resistance to microbial action.
Polyethene contains a stable, non-polar carbon-carbon backbone that soil micro-organisms cannot digest.
Materials that resist natural biological breakdown by bacteria and fungi are classified as non-biodegradable.

Anahtar Kavram

Biodegradable vs Non-Biodegradable Polymers
Soru 12Soru →

The glass manufacturing industry located in Ughelli, Delta State, was established in that area primarily due to the ready availability of which key raw material?

Cevabı ve açıklamayı göster

Cevap: Silica sand

Cevap

Silica sand
Silica sand (SiO2SiO_2) forms the main structural matrix of commercial glass. Chemical industries that rely on high volumes of heavy raw materials, such as the glass factory at Ughelli, are sited directly near silica sand deposits to reduce transport overheads.

Adım Adım Çözüm

1
Identify the primary raw material required for glass manufacturing.
Glass is predominantly composed of silicon(IV) oxide (SiO2SiO_2), which is obtained from silica sand.
Chemical industries are sited close to heavy bulk raw materials to minimize transportation costs.
2
Relate the raw material to the specified industrial location in Nigeria.
Ughelli in Delta State has vast natural deposits of high-purity silica sand, making it an ideal site for glass production.
Proximity to raw materials is the key siting factor for bulk material chemical industries.

Anahtar Kavram

Industrial Siting Factors and Raw Material Allocation
Tahmini Süre:45s
Soru 13Soru →

In the industrial synthesis of trioxonitrate(V) acid (HNO3\text{HNO}_3) via the Ostwald process, ammonia (NH3\text{NH}_3) gas is oxidized by oxygen over a platinum-rhodium gauze catalyst at approximately 850∘C850^\circ\text{C} and 5 atm5\text{ atm}. Which balanced chemical equation correctly represents this initial catalytic oxidation step, and what is the precise thermodynamic role of the catalyst?

Cevabı ve açıklamayı göster

Cevap: 4NH3(g)+5O2(g)→4NO(g)+6H2O(g)4\text{NH}_3(g) + 5\text{O}_2(g) \rightarrow 4\text{NO}(g) + 6\text{H}_2\text{O}(g); the catalyst increases the forward reaction rate by lowering the activation energy without shifting the position of dynamic equilibrium.

Cevap

The equation 4NH3(g)+5O2(g)→4NO(g)+6H2O(g)4\text{NH}_3(g) + 5\text{O}_2(g) \rightarrow 4\text{NO}(g) + 6\text{H}_2\text{O}(g) correctly represents the initial stage of the Ostwald process, where the platinum-rhodium catalyst lowers the activation energy to increase the reaction rate without altering the position of equilibrium.
In the Ostwald process for manufacturing trioxonitrate(V) acid (HNO3\text{HNO}_3), the initial reaction is the exothermic oxidation of ammonia gas to nitrogen(II) oxide gas according to the equation 4NH3(g)+5O2(g)→4NO(g)+6H2O(g)4\text{NH}_3(g) + 5\text{O}_2(g) \rightarrow 4\text{NO}(g) + 6\text{H}_2\text{O}(g). The platinum-rhodium wire gauze catalyst accelerates the reaction by lowering the activation energy barrier, enabling rapid formation of NO\text{NO} at high operating temperatures (850∘C850^\circ\text{C}). It does not affect the position of dynamic equilibrium or change the equilibrium yield of products.

Adım Adım Çözüm

1
Identify the primary chemical reaction in stage 1 of the Ostwald process
Ammonia reacts with oxygen in a 4:5 mole ratio to yield nitrogen(II) oxide and steam: 4NH3(g)+5O2(g)→4NO(g)+6H2O(g)4\text{NH}_3(g) + 5\text{O}_2(g) \rightarrow 4\text{NO}(g) + 6\text{H}_2\text{O}(g).
Direct catalytic oxidation of ammonia produces NO\text{NO} gas first; subsequent cooling and oxidation converts NO\text{NO} to NO2\text{NO}_2 before absorption in water.
2
Analyze the catalytic role of the platinum-rhodium gauze
The catalyst provides an alternative reaction pathway with a lower activation energy (EaE_a).
Catalysts increase the rate of attainment of equilibrium equally in both forward and reverse directions but do not change ΔH\Delta H, ΔG\Delta G, or the position of equilibrium (KeqK_{eq}).

Anahtar Kavram

Ostwald Process and Catalytic Principles
Soru 14Soru →

Agricultural soil adjacent to a battery recycling plant became severely contaminated with toxic lead compounds. Environmental engineers applied slaked lime, Ca(OH)2\text{Ca(OH)}_2, to immobilize the heavy metal by precipitating it as insoluble lead(II) hydroxide, Pb(OH)2\text{Pb(OH)}_2. However, excessive liming caused the soil pH to rise above 10.510.5, triggering a secondary leaching event where lead concentrations in groundwater rapidly increased. Which chemical reaction accounts for the unexpected re-mobilization of lead under strongly alkaline soil conditions?

Cevabı ve açıklamayı göster

Cevap: Formation of soluble tetrahydroxoplumbate(II) complex ions, [Pb(OH)4]2−[\text{Pb(OH)}_4]^{2-}, due to the amphoteric behavior of lead(II) compounds in excess base

Cevap

The re-mobilization of lead in strongly alkaline soil is caused by the formation of soluble tetrahydroxoplumbate(II) complex ions, [Pb(OH)4]2−[\text{Pb(OH)}_4]^{2-}, owing to the amphoteric character of lead(II) compounds.
Lead(II) compounds exhibit amphoterism. While moderate liming precipitates lead as insoluble Pb(OH)2\text{Pb(OH)}_2, over-liming creates a high concentration of OH−\text{OH}^- ions (pH > 10.5). This causes the precipitate to dissolve by forming the soluble complex anion [Pb(OH)4]2−[\text{Pb(OH)}_4]^{2-} (tetrahydroxoplumbate(II)), leading to groundwater pollution.

Adım Adım Çözüm

1
Analyze the chemical behavior of lead(II) hydroxide upon initial neutralization.
Adding moderate amounts of base causes Pb2+\text{Pb}^{2+} ions to precipitate as insoluble lead(II) hydroxide: Pb(aq)2++2OH(aq)−→Pb(OH)2(s)\text{Pb}^{2+}_{(\text{aq})} + 2\text{OH}^-_{(\text{aq})} \rightarrow \text{Pb(OH)}_{2(\text{s})}.
This temporarily immobilizes heavy metal contamination in the soil matrix.
2
Determine the effect of excess hydroxide ions (pH > 10.5) on the precipitate.
Because lead is an amphoteric metal (similar to aluminium and zinc), its oxide and hydroxide react with excess alkali: Pb(OH)2(s)+2OH(aq)−→[Pb(OH)4](aq)2−\text{Pb(OH)}_{2(\text{s})} + 2\text{OH}^-_{(\text{aq})} \rightarrow [\text{Pb(OH)}_4]^{2-}_{(\text{aq})}.
The formation of the complex tetrahydroxoplumbate(II) anion brings lead back into aqueous solution, increasing heavy metal leaching into groundwater.

Anahtar Kavram

Amphoteric behavior of heavy metals in soil remediation and waste management
Tahmini Süre:2m 0s
Soru 15Soru →

In a municipal water purification plant, raw river water undergoes several sequential treatment processes to make it safe for public consumption. What is the correct chronological sequence of these major water treatment stages, from raw water intake to final distribution?

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence of municipal water treatment is: Coagulation/flocculation → Sedimentation → Filtration → Disinfection.
The correct sequence follows the logical progression of municipal water purification: Coagulation chemically aggregates fine particles into flocs; Sedimentation allows these heavy flocs to settle to the bottom; Filtration passes the clarified liquid through sand/gravel to catch residual solids; Disinfection is performed last with chlorine to destroy pathogenic microorganisms in clear water.

Adım Adım Çözüm

1
Identify the initial chemical coagulation step
Alum, Al2(SO4)3Al_2(SO_4)_3, is added to raw water to neutralize colloidal charges and form floc particles.
Fine suspended particles will not settle naturally without first being coagulated into larger masses.
2
Determine the settling process
Water flows slowly through sedimentation tanks where heavy flocs sink to the bottom.
Gravity settling removes the bulk of solid impurities created during coagulation.
3
Identify the fine solid removal process
Clarified water passes through coarse sand, fine sand, and gravel beds.
Filtration removes any remaining microscopic suspended particles.
4
Determine the final biological purification step
Chlorine is injected into the clear filtered water.
Chlorination destroys disease-causing microbes and guarantees biological safety throughout the distribution network.

Anahtar Kavram

Stages of Municipal Water Treatment
Soru 16Soru →

In the industrial production of cement in Nigeria, such as at the factory in Ewekoro, Ogun State, proximity to the bulk raw material is the primary factor influencing site selection. Which of the following is the principal raw material extracted at the site for this process?

Cevabı ve açıklamayı göster

Cevap: Limestone

Cevap

Limestone is the principal raw material for cement production and determines factory siting due to its bulk and heavy transport cost.
Limestone is the chief calcareous raw material needed in large quantities for burning in kilns to produce cement clinker. Because of its weight and bulk, cement factories are located directly at limestone quarry sites to minimize transportation costs.

Adım Adım Çözüm

1
Identify the industrial chemical process
The process described is cement manufacturing in Nigeria.
Establishing the main product helps determine the required starting materials.
2
Analyze raw material requirements for cement production
Limestone (CaCO3CaCO_3) forms the primary raw material component (calcareous material) used in massive volume.
Heavy industries sit close to raw materials when transport costs of heavy raw inputs outweigh other factors.
3
Evaluate Nigerian industrial geography context
Ewekoro in Ogun State and Nkalagu in Ebonyi State were selected for major cement plants specifically due to large natural limestone deposits.
This confirms limestone as the critical siting raw material.

Anahtar Kavram

Raw material availability as a major siting factor for heavy chemical industries.
Tahmini Süre:45s
Soru 17Soru →

A chemical manufacturing firm in Nigeria plans to establish a large-scale heavy chemical plant producing tetraoxosulfate(VI) acid (H2SO4H_2SO_4) and superphosphate fertilizers using imported elemental sulfur and phosphate rock. Considering raw material transportation, energy requirements, environmental trade-offs, and product distribution logistics, which of the following is the primary economic factor dictating that this plant be sited near a coastal seaport rather than inland near agricultural consumer regions?

Cevabı ve açıklamayı göster

Cevap: Minimizing the high freight costs of transporting bulky, low-value imported raw materials inland

Cevap

Minimizing the high freight costs of transporting bulky, low-value imported raw materials inland
Heavy chemical manufacturing involving bulky imported raw materials (such as sulfur and rock phosphate) is primarily raw-material-oriented. Transporting heavy solid raw materials inland from ports incurs massive transport costs, so siting the facility near a coastal port minimizes overall supply chain expenditure.

Adım Adım Çözüm

1
Classify the industry type and identify the primary inputs.
Production of tetraoxosulfate(VI) acid and fertilizers is a heavy chemical industry requiring large volumes of heavy imported solid raw materials (sulfur and phosphate rock).
Heavy chemical industries are material-oriented or market-oriented depending on the weight-loss or bulkiness of inputs versus outputs.
2
Analyze transport economics for imported bulky raw materials versus finished product.
Transporting thousands of tonnes of imported solid minerals inland over long distances incurs enormous freight costs, whereas transporting concentrated acid or packaged fertilizer is more manageable.
Proximity to raw material entry points (seaports) minimizes overland haulage costs for heavy imported inputs.
3
Evaluate potential chemical and operational misattributions.
Seawater cannot be used directly in chemical formulations due to salt contamination, emissions regulations apply anywhere, and physical water flow does not catalyze reactions.
Eliminates incorrect technical and regulatory distractors.

Anahtar Kavram

Siting Factors for Heavy Chemical Industries (Raw Material Proximity vs. Market Proximity)
Tahmini Süre:2m 0s
Soru 18Soru →

Match each chemical industry operation in Nigeria with its primary siting factor and chemical raw material requirement.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Petrochemical urea fertilizer plant (e.g., located at Eleme/Onne)
Commercial container and sheet glass factory (e.g., located at Ughelli/Igbokoda)
Chlor-alkali electrochemical manufacturing facility
Secondary mini-steel rolling mill using electric arc furnaces

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

The correct pairings align the petrochemical urea plant with natural gas fields (feedstock and fuel), the glass factory with silica sand deposits (bulk solid reduction), the chlor-alkali facility with brine deposits and power supply (electrolysis requirements), and the mini-steel mill with urban scrap markets (market-oriented secondary metallurgy).
The matches correctly link each industry to its primary chemical input and siting logic: urea synthesis requires natural gas feedstock, glass manufacturing requires heavy silica sand deposits, chlor-alkali requires brine and power for electrolysis, and secondary mini-steel mills require scrap metal availability and market access.

Adım Adım Çözüm

1
Analyze the chemical synthesis pathways for urea fertilizer manufacture.
Identify natural gas (CH4CH_4) as the hydrogen source for steam reforming to make ammonia (NH3NH_3), which is combined with carbon dioxide (CO2CO_2) to yield urea.
Natural gas serves a dual role as both chemical feedstock and thermal energy source, necessitating plant siting near gas fields.
2
Examine the material transport economics for commercial glass manufacturing.
Determine that high-purity silica sand (SiO2SiO_2) forms the bulk of the raw material mass.
Transporting heavy, low-unit-cost raw silica across long distances is economically inefficient compared to locating near riverine/coastal sand deposits.
3
Evaluate the inputs for industrial chlor-alkali production.
Connect concentrated aqueous sodium chloride (NaCl(aq)NaCl(aq)) and electric power to the production of sodium hydroxide (NaOHNaOH) and chlorine gas (Cl2Cl_2).
Electrochemical chlor-alkali cells rely on high power input and continuous brine supply.
4
Differentiate primary steelmaking from secondary scrap-based steel mills.
Associate secondary mini-mills with urban scrap centers and market proximity.
Unlike blast furnace primary steel production (which locates near iron ore and metallurgical coal), mini-mills re-melt local metal scrap in electric arc furnaces, making them market-oriented.

Anahtar Kavram

Raw material dependencies and industrial siting economics in chemical and metallurgical industries
Soru 19Soru →

A major chlor-alkali chemical plant is sited near a coastal marine environment to optimize production efficiency. Which primary raw material is extracted at this location for the industrial electrolysis that yields sodium hydroxide, chlorine gas, and hydrogen gas?

Cevabı ve açıklamayı göster

Cevap: Sodium chloride (concentrated brine or sea salt)

Cevap

Sodium chloride (concentrated brine or sea salt) is the primary raw material for the chlor-alkali industry.
The chlor-alkali industry relies on the electrolysis of concentrated sodium chloride solution (brine), which yields sodium hydroxide at the cathode/solution along with chlorine gas at the anode and hydrogen gas at the cathode. Siting these factories near marine coastal zones or salt deposits ensures a direct and abundant supply of the primary raw material, sodium chloride.

Adım Adım Çözüm

1
Identify the chemical industry process specified in the prompt.
The process described is the chlor-alkali industry, which produces sodium hydroxide (NaOHNaOH), chlorine (Cl2Cl_2), and hydrogen (H2H_2).
Recognizing the end-products pinpoints the required industrial process.
2
Determine the necessary ionic starting material containing sodium and chloride ions.
Electrolysis of aqueous sodium chloride (NaClNaCl), commonly sourced from sea salt or brine deposits near coastal areas, provides Na+Na^+ and Cl−Cl^- ions.
Chemical industries are frequently sited near their primary raw material sources to minimize raw material transport costs.

Anahtar Kavram

Chlor-alkali process raw materials and industrial siting factors
Soru 20Soru →

A chemical engineer is selecting a location for a new heavy chemical manufacturing plant producing fertilizer in Nigeria. How should the following siting factors be arranged in decreasing order of priority (from most critical to least critical)?

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct order of priority from most critical to least critical is: Proximity to bulk raw materials, Availability of continuous industrial power and water supply, Access to heavy transport infrastructure, and Proximity to immediate urban consumer retail markets.
For heavy chemical manufacturing plants, proximity to raw materials is paramount because raw inputs are bulky and costly to transport. Availability of continuous power and water ranks second to ensure uninterrupted continuous-flow operations. Heavy transport infrastructure (rail and sea links) ranks third to facilitate bulk freight movements. Proximity to local urban consumer markets is the lowest priority because heavy chemicals are intermediate goods sold to other industries, not end-user retail products.

Adım Adım Çözüm

1
Analyze the primary cost driver for heavy chemical manufacturing.
Heavy chemical industries process huge volumes of bulky, low-value-per-unit raw inputs.
Locating the plant close to raw material deposits minimizes the massive freight expenses associated with transporting crude inputs.
2
Evaluate key processing utility requirements.
Industrial power grids and high-capacity water sources represent the second highest priority.
Heavy chemical reactions operate continuously and demand vast amounts of water for cooling and steam generation along with reliable electric power.
3
Compare transport logistics against market location.
Access to heavy transport networks (railways/ports) takes priority over urban retail market proximity.
Heavy chemicals serve as raw materials for secondary factories across wide geographic regions rather than being sold in local urban retail markets.

Anahtar Kavram

Priority of siting factors in heavy vs light chemical industries
Tahmini Süre:1m 30s
Sayfa 1 / 4Sonraki
Chemistry, Industry and the Environment Alıştırma Soruları — JAMB UTME | Examkin