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The nitrate polyatomic ion is characterized by the chemical formula NO₃⁻, signifying a net charge of -1.
Answer: True
Explanation: The nitrate polyatomic ion is indeed defined by the chemical formula NO₃⁻, indicating a net charge of -1. Salts containing this ion are commonly referred to as nitrates.
The nitrate ion features a central nitrogen atom bonded to three oxygen atoms arranged in a trigonal planar geometry, not a linear arrangement.
Answer: True
Explanation: The atomic arrangement within the nitrate ion is trigonal planar, a consequence of electron delocalization via resonance, rather than a linear configuration.
Within the nitrate anion (NO₃⁻), the nitrogen atom exhibits a formal oxidation state of +5.
Answer: True
Explanation: The central nitrogen atom in the nitrate anion is indeed assigned an oxidation state of +5, which represents the maximum possible oxidation state for nitrogen.
The nitrate ion functions as a potent oxidizing agent, particularly under specific reaction conditions, rather than a weak one.
Answer: True
Explanation: Nitrate is recognized as a strong oxidizing agent, especially in environments with high temperatures or the presence of hydrogen ions, as demonstrated by its role in explosives.
The nitrate ion (NO₃⁻) is the conjugate base of nitric acid (HNO₃), not nitrous acid (HNO₂).
Answer: True
Explanation: The nitrate ion is formed when nitric acid (HNO₃) loses a proton, making it the conjugate base of HNO₃.
The CAS Registry Number for the nitrate ion is 14797-55-8.
Answer: True
Explanation: The Chemical Abstracts Service (CAS) Registry Number specifically assigned to the nitrate ion is 14797-55-8.
Nitrite (NO₂⁻) is formed from nitrate (NO₃⁻) through a reduction process, not an oxidation process.
Answer: True
Explanation: The transformation of nitrate to nitrite involves a gain of electrons (reduction), typically mediated by microbial enzymes.
The trigonal planar geometry of the nitrate ion is a consequence of electron delocalization through chemical resonance.
Answer: True
Explanation: The delocalization of electrons via resonance structures accounts for the symmetrical trigonal planar arrangement of atoms in the nitrate ion.
The nitrate ion is formed when nitric acid (HNO₃) loses a proton (H⁺), not a neutron.
Answer: True
Explanation: The formation of the nitrate ion from nitric acid involves the dissociation of a proton (H⁺), defining it as the conjugate base.
The molar mass of the nitrate ion (NO₃⁻) is approximately 62.004 g/mol.
Answer: True
Explanation: The calculated molar mass for the nitrate ion (NO₃⁻), based on atomic weights, is approximately 62.004 g/mol.
Nitrite (NO₂⁻) is a product of the reduction of nitrate (NO₃⁻).
Answer: True
Explanation: The formation of nitrite from nitrate involves a gain of electrons, classifying it as a reduction reaction.
What is the chemical formula and charge of the nitrate polyatomic ion?
Answer: NO₃⁻ with a charge of -1
Explanation: The nitrate polyatomic ion is characterized by the chemical formula NO₃⁻, signifying a net charge of -1.
Which term best describes the arrangement of atoms in the nitrate ion?
Answer: Trigonal planar
Explanation: The atoms within the nitrate ion are arranged in a trigonal planar geometry due to the delocalization of electrons through resonance.
What is the oxidation state of the nitrogen atom in the nitrate anion (NO₃⁻)?
Answer: +5
Explanation: In the nitrate anion, the nitrogen atom is assigned an oxidation state of +5.
How does the nitrate ion function in chemical reactions?
Answer: As a potent oxidizing agent, particularly at high temperatures
Explanation: Nitrate is recognized for its capacity to act as a strong oxidizing agent, especially under conditions of elevated temperature.
The nitrate ion (NO₃⁻) is the conjugate base of which acid?
Answer: Nitric acid (HNO₃)
Explanation: The nitrate ion (NO₃⁻) is the conjugate base of nitric acid (HNO₃).
What is the approximate molar mass of the nitrate ion (NO₃⁻)?
Answer: 62.004 g/mol
Explanation: The molar mass of the nitrate ion (NO₃⁻) is calculated to be approximately 62.004 grams per mole.
What is the chemical formula for nitrite, the reduced form of nitrate?
Answer: NO₂⁻
Explanation: The chemical formula for the nitrite ion, which is a reduced form of nitrate, is NO₂⁻.
Nitrate salts are not exclusively found in industrial settings; they occur naturally, notably in arid environments where they can form significant deposits.
Answer: True
Explanation: Natural nitrate deposits, such as those found in arid regions, serve as sources of nitrate salts, demonstrating their occurrence beyond industrial contexts.
Lightning is a natural atmospheric phenomenon that contributes to the environmental formation of nitrate ions through the reaction of atmospheric nitrogen and oxygen.
Answer: True
Explanation: The high energy discharge of lightning facilitates the synthesis of nitrogen oxides from atmospheric N₂ and O₂, which subsequently form nitrates that enter the biosphere via precipitation.
Lightning converts atmospheric nitrogen and oxygen into nitrogen oxides, which subsequently form nitrates, not ozone.
Answer: True
Explanation: Lightning's energy facilitates the formation of nitrogen oxides (NOx) from atmospheric N₂ and O₂, leading to nitrate production, not ozone.
Where can nitrate salts be found naturally on Earth?
Answer: Arid environments as large deposits
Explanation: Significant natural deposits of nitrate salts are found in arid regions, such as the Atacama Desert.
What natural atmospheric phenomenon contributes to the formation of nitrates?
Answer: Lightning strikes
Explanation: Lightning provides the energy necessary for atmospheric nitrogen and oxygen to react, forming nitrogen oxides that lead to nitrate production.
Nitrate tends to be unstable and is actively metabolized by microorganisms in ecosystems, preventing its accumulation to high levels.
Answer: True
Explanation: Contrary to accumulating due to stability, nitrate is readily transformed by microbial activity, particularly denitrification, which limits its persistence in natural ecosystems.
Denitrifying bacteria convert nitrate into nitrite as an intermediate step in their anaerobic respiratory process, not as the final step.
Answer: True
Explanation: The reduction of nitrate to nitrite is indeed an initial step in denitrification, with subsequent steps leading to the release of nitrogen gas.
Nitrate ranks relatively high as an electron acceptor in anaerobic respiration, above sulfate and iron, but below oxygen.
Answer: True
Explanation: In terms of redox potential for anaerobic respiration, nitrate is a more favorable electron acceptor than sulfate or iron(III), but less favorable than oxygen.
The conversion of nitrate to nitrite by bacteria is indeed the initial step in the biological process of denitrification.
Answer: True
Explanation: Biological denitrification commences with the enzymatic reduction of nitrate (NO₃⁻) to nitrite (NO₂⁻) by various microorganisms.
Nitrate is considered an essential nutrient for plant growth, vital for the synthesis of proteins and nucleic acids.
Answer: True
Explanation: Nitrate is a primary source of nitrogen for plants, indispensable for constructing essential biomolecules like proteins and nucleic acids, thus supporting overall plant development.
Excessive nitrate fertilizer use poses significant environmental risks, including water pollution and eutrophication.
Answer: True
Explanation: Runoff from agricultural lands treated with excessive nitrate fertilizers can lead to eutrophication of water bodies, causing ecological damage.
High nitrate concentrations can be detrimental to aquatic life, potentially inhibiting growth and causing stress, and contribute to eutrophication.
Answer: True
Explanation: While serving as a nutrient, excessive nitrate levels in aquatic systems can lead to eutrophication and exert toxic effects on various aquatic organisms.
Increased nitrate deposition can negatively impact soil microbial populations and disrupt essential nutrient cycling processes.
Answer: True
Explanation: Elevated nitrate levels resulting from deposition can alter soil chemistry, adversely affecting microbial communities and disrupting natural nutrient cycles.
Dietary nitrate intake significantly influences the body's production of nitric oxide (NO), a crucial signaling molecule.
Answer: True
Explanation: Ingestion of nitrate leads to increased plasma nitrate levels, which in turn enhances the endogenous production of nitric oxide (NO), vital for physiological regulation.
Microorganisms generally decrease the stability and concentration of nitrate in natural water bodies through metabolic processes.
Answer: True
Explanation: Microbial activity, particularly denitrification, actively consumes nitrate, thereby reducing its concentration and stability in aquatic environments.
Nitrate ions are essential for plants to synthesize proteins and nucleic acids, forming the basis of their nitrogen nutrition.
Answer: True
Explanation: Nitrate serves as a fundamental nitrogen source for plants, enabling the synthesis of vital macromolecules such as proteins and nucleic acids.
Nitrate is a stronger electron acceptor in anaerobic respiration compared to iron (Fe(III)).
Answer: False
Explanation: Nitrate is a weaker electron acceptor than iron(III) in anaerobic respiration; iron(III) has a higher redox potential.
The primary function of nitrate in plants is as a nitrogen source for synthesizing organic molecules, not for structural support.
Answer: True
Explanation: Nitrate's principal role in plant physiology is providing nitrogen for biosynthesis, rather than contributing directly to structural components.
Nitrate contributes to eutrophication by acting as a nutrient that stimulates excessive algal growth in aquatic systems.
Answer: True
Explanation: Excessive nitrate loading in water bodies fuels algal blooms, a process known as eutrophication, which can severely degrade water quality.
Nitrate functions not only as a nutrient for plants but also plays a crucial role as a signaling molecule, regulating various physiological processes.
Answer: True
Explanation: Beyond its nutritional role, nitrate acts as a signaling agent in plants, influencing developmental pathways and physiological responses.
Microorganisms play a significant role in the nitrogen cycle by metabolizing nitrate. This biological activity generally leads to decreased stability and concentration of nitrate in natural aquatic environments.
Answer: True
Explanation: Through processes like denitrification, microorganisms actively transform nitrate, making it less stable and reducing its concentration in aquatic ecosystems.
Why is nitrate considered unstable in natural environments?
Answer: It is metabolized by microorganisms and reacts with reductants.
Explanation: Nitrate's instability in natural settings arises from its susceptibility to microbial metabolism and reactions with reducing agents, preventing its accumulation.
What is the role of denitrifying bacteria in the nitrogen cycle concerning nitrate?
Answer: They use nitrate as a terminal electron acceptor for respiration, converting it to nitrogen gas.
Explanation: Denitrifying bacteria utilize nitrate as an electron acceptor in anaerobic respiration, ultimately reducing it to atmospheric nitrogen gas (N₂).
On the redox scale for anaerobic respiration, where does nitrate rank compared to other common electron acceptors?
Answer: Just below oxygen, and above manganese, iron, and sulfate
Explanation: Nitrate ranks high on the redox scale for anaerobic respiration, positioned below oxygen but above manganese, iron, and sulfate as an electron acceptor.
What is the first biological step in the denitrification process involving nitrate?
Answer: Reduction of nitrate to nitrite (NO₂⁻)
Explanation: The initial biological step in denitrification is the enzymatic reduction of nitrate (NO₃⁻) to nitrite (NO₂⁻).
Which of the following is a potential negative implication of nitric oxide (NO) produced during denitrification?
Answer: It can form free radicals, accelerating tissue degradation.
Explanation: While NO has signaling roles, it can also form free radicals that contribute to oxidative stress and tissue damage.
What is the fundamental role of nitrate in plant nutrition?
Answer: It is a primary source of nitrogen for synthesizing organic molecules.
Explanation: Nitrate is essential for plants as it provides the nitrogen required for the synthesis of proteins, nucleic acids, and other vital organic compounds.
What environmental problem can result from excessive use of nitrate fertilizers?
Answer: Eutrophication of water bodies
Explanation: Excessive nitrate runoff into aquatic systems leads to eutrophication, characterized by over-enrichment of nutrients and subsequent ecological disruption.
What are the potential toxic effects of high nitrate concentrations (>30 ppm) on aquatic life?
Answer: Inhibition of growth, immune system impairment, and stress
Explanation: Concentrations of nitrate exceeding 30 ppm can negatively impact aquatic organisms by inhibiting growth, impairing immune function, and inducing physiological stress.
How does increased nitrate deposition impact soil ecosystems?
Answer: It disrupts microbial populations and nutrient cycling.
Explanation: Elevated nitrate deposition can alter soil chemistry, leading to disruptions in microbial communities and interference with essential nutrient cycling processes.
What effect does dietary nitrate intake have on the body regarding nitric oxide (NO)?
Answer: It enhances the production of nitric oxide (NO).
Explanation: Dietary nitrate intake contributes to increased plasma nitrate levels, which subsequently enhances the endogenous synthesis of nitric oxide (NO).
How do microorganisms influence nitrate levels in natural waters?
Answer: They consume nitrate, making it less stable and reducing its concentration.
Explanation: Microorganisms actively metabolize nitrate, leading to its reduced stability and concentration in aquatic environments.
Nitrates find applications in the food preservation industry and as components in certain cleaning agents, though their primary uses are often in fertilizers and explosives.
Answer: True
Explanation: While fertilizers and explosives are major applications, nitrates also serve roles in food preservation and as components in cleaning agents, as indicated by the source material.
Ammonium nitrate and potassium nitrate are widely utilized as fertilizers due to their solubility and availability of nitrogen for plant uptake.
Answer: True
Explanation: Ammonium nitrate and potassium nitrate are common agricultural fertilizers, valued for their high water solubility which ensures efficient nitrogen delivery to plants.
Nitrates serve as essential oxidizing agents in the formulation of gunpowder and other explosives, enabling rapid combustion.
Answer: True
Explanation: The oxidizing properties of nitrates are critical for the rapid combustion required in explosives like gunpowder.
Sodium nitrate has industrial applications in the ceramics industry and in processes involving metal surface treatments.
Answer: True
Explanation: Sodium nitrate is utilized in the ceramics sector and for specific metal surface treatments, in addition to its role in glass manufacturing.
Historically, nitrate-based film bases (nitrocellulose) were used in photography but were phased out due to their high flammability, not favored for non-flammable properties.
Answer: True
Explanation: The high flammability of nitrocellulose film bases led to their replacement by safer alternatives, indicating they were not favored for non-flammable characteristics.
Organic nitrate esters, such as glyceryl trinitrate, are employed medically as nitrovasodilators to manage conditions like myocardial infarction.
Answer: True
Explanation: Glyceryl trinitrate and similar organic nitrate esters function as nitrovasodilators, used therapeutically for acute coronary syndromes and myocardial infarction.
Nitrites, often derived from nitrates, are incorporated into cured meats primarily to stabilize color and inhibit the growth of spoilage and pathogenic bacteria.
Answer: True
Explanation: Nitrites play a critical role in the curing process of meats, contributing to color fixation and preventing microbial proliferation, including that of dangerous pathogens.
A nitrate ester is a covalent compound characterized by the functional group -ONO₂, where an organic radical (R) is bonded to the nitrate group. This distinguishes them from inorganic nitrate salts.
Answer: True
Explanation: Nitrate esters are organic compounds featuring a covalent bond between an organic group and the nitrate functional group (-ONO₂), differentiating them from ionic nitrate salts.
Ammonium nitrate is a common and effective nitrate fertilizer used to enhance agricultural crop yields.
Answer: True
Explanation: Ammonium nitrate is a widely employed fertilizer known for its efficacy in boosting crop production due to its high nitrogen content.
Organic nitrate derivatives, such as isosorbide mononitrate, are used medically as nitrovasodilators.
Answer: True
Explanation: Isosorbide mononitrate belongs to the class of organic nitrate derivatives known as nitrovasodilators, employed in cardiovascular therapy.
Nitrate esters are covalent compounds with the structure R-ONO₂, distinct from inorganic nitrate salts.
Answer: True
Explanation: The designation 'nitrate ester' refers to organic molecules with a covalent R-ONO₂ linkage, differentiating them chemically from inorganic salts containing the NO₃⁻ ion.
Nitrates are used in cured meats for preservation, color stabilization, and inhibition of bacterial growth.
Answer: True
Explanation: The functions of nitrates/nitrites in cured meats extend beyond flavor to include critical roles in preservation, color maintenance, and microbial control.
According to the introduction, what are two common applications of nitrates?
Answer: Fertilizers and explosives
Explanation: The introductory context highlights fertilizers and explosives as primary industrial applications of nitrates.
Which of the following is NOT listed as a common nitrate fertilizer?
Answer: Phosphate nitrate
Explanation: Common nitrate fertilizers include ammonium, potassium, and calcium nitrates. 'Phosphate nitrate' is not listed as a standard fertilizer type.
In firearms, nitrates primarily function as:
Answer: Oxidizing agents
Explanation: Nitrates serve as oxidizing agents in gunpowder and other explosive formulations, providing oxygen for rapid combustion.
Which industrial application of sodium nitrate is mentioned in the source?
Answer: Removing air bubbles from molten glass
Explanation: Sodium nitrate is used in the glass industry, specifically for the removal of air bubbles from molten glass.
Why did photographic film production transition away from nitrate film bases?
Answer: Nitrate bases were highly flammable.
Explanation: The high flammability of nitrate-based film (nitrocellulose) was the primary reason for its replacement with safer cellulose acetate alternatives.
What class of drugs do organic nitrate esters like glyceryl trinitrate belong to?
Answer: Nitrovasodilators
Explanation: Organic nitrate esters such as glyceryl trinitrate are classified as nitrovasodilators, used for their effects on blood vessel dilation.
In cured meats, nitrites (often derived from nitrates) play a role in:
Answer: Preserving the meat, maintaining color, and inhibiting bacteria
Explanation: Nitrites are crucial in cured meats for preservation, color stabilization, and the inhibition of bacterial growth.
Which of the following is a medically used organic nitrate derivative?
Answer: Isosorbide mononitrate
Explanation: Isosorbide mononitrate is an organic nitrate derivative commonly used in medicine as a vasodilator.
What does the term 'nitrate ester' refer to in a chemical context?
Answer: A covalent compound with the structure R-ONO₂
Explanation: A nitrate ester is defined as a covalent compound containing the -ONO₂ functional group attached to an organic radical (R).
Besides preservation and color, what is another function of nitrates/nitrites in cured meats?
Answer: Inhibiting the growth of harmful bacteria
Explanation: Nitrites play a crucial role in inhibiting the growth of harmful bacteria, such as Clostridium botulinum, in cured meat products.
The primary human health concerns regarding nitrate intake involve its potential conversion to carcinogenic nitrosamines and its indirect role in causing methemoglobinemia, particularly in vulnerable populations.
Answer: True
Explanation: Key health concerns related to nitrate consumption include the formation of nitrosamines and the risk of methemoglobinemia, especially in infants, mediated by nitrite.
Infants are significantly more susceptible to methemoglobinemia than adults due to lower levels of the enzyme required to reduce methemoglobin and higher relative water intake.
Answer: True
Explanation: Infants exhibit heightened susceptibility to methemoglobinemia owing to immature enzyme systems for methemoglobin reduction and a greater body water percentage relative to mass.
The U.S. EPA has established a maximum contaminant level (MCL) of 10 mg/L for nitrate in drinking water.
Answer: True
Explanation: Under the Safe Drinking Water Act, the U.S. EPA mandates a maximum contaminant level (MCL) of 10 mg/L for nitrate in public drinking water supplies.
The acceptable daily intake (ADI) for nitrate ions, as established by JEFCA, is in the range of 0 to 3.7 mg per kilogram of body weight per day.
Answer: True
Explanation: The Joint FAO/WHO Expert Committee on Food Additives (JEFCA) has determined the acceptable daily intake (ADI) for nitrate ions to be between 0 and 3.7 mg/kg body weight/day.
Leafy green vegetables and beetroot juice are recognized as significant dietary sources of nitrate for humans.
Answer: True
Explanation: Vegetables such as spinach and arugula, along with beetroot juice, are primary dietary contributors of nitrate to the human diet.
Antioxidants, such as Vitamin C, can effectively inhibit the formation of potentially carcinogenic nitrosamines during the curing of meats.
Answer: True
Explanation: The addition of antioxidants like ascorbic acid (Vitamin C) is a recognized strategy to suppress the formation of nitrosamines during meat curing.
Symptoms of nitrate poisoning in animals include increased heart rate and respiration, and potentially a characteristic pale blue or brown coloration of blood and tissues due to methemoglobin formation.
Answer: True
Explanation: Clinical signs of nitrate poisoning in livestock can include cardiovascular and respiratory distress, along with cyanosis resulting from methemoglobinemia.
Feed containing less than 0.5% nitrate (dry basis) is generally considered safe for beef cattle and sheep, though specific thresholds may vary.
Answer: True
Explanation: General safety guidelines suggest that feed with nitrate levels below 0.5% (dry basis) is typically safe for ruminants like cattle and sheep.
The primary health risk of nitrate in infant digestion is its conversion to nitrite, which can lead to methemoglobinemia.
Answer: True
Explanation: Nitrate's conversion to nitrite in the infant gut is the critical pathway leading to methemoglobinemia, a condition impairing oxygen transport.
Nitrates are added to processed meats for purposes including preservation and color stabilization, not solely for flavor enhancement.
Answer: True
Explanation: Beyond flavor, nitrates and nitrites are essential for the preservation and color development in cured meat products.
Nitrate itself does not directly cause methemoglobinemia; rather, its reduction to nitrite by bacteria is the critical step leading to this condition.
Answer: True
Explanation: Methemoglobinemia is primarily induced by nitrite, which is formed from nitrate through microbial action in the digestive tract.
The main health risk of nitrate in drinking water for infants stems from its conversion to nitrite, which causes methemoglobinemia, not from its direct toxicity.
Answer: True
Explanation: The primary concern for infants regarding nitrate in water is not direct toxicity, but the potential for bacterial conversion to nitrite, leading to methemoglobinemia.
What are the two main concerns regarding nitrate toxicity in humans?
Answer: Formation of carcinogenic nitrosamines and methemoglobinemia
Explanation: The primary human health concerns linked to nitrate intake are the potential formation of carcinogenic nitrosamines and the induction of methemoglobinemia.
Why are infants particularly susceptible to methemoglobinemia caused by nitrites (derived from nitrates)?
Answer: They have lower enzyme activity and higher water intake relative to body weight.
Explanation: Infants' susceptibility stems from immature enzyme systems for methemoglobin reduction and a higher body water percentage relative to their mass.
What is the maximum contaminant level for nitrate in drinking water set by the U.S. EPA?
Answer: 10 mg/L
Explanation: The U.S. EPA has established a maximum contaminant level (MCL) of 10 mg/L for nitrate in drinking water.
What is the established acceptable daily intake (ADI) range for nitrate ions per kilogram of body weight per day?
Answer: 0 to 3.7 mg
Explanation: The acceptable daily intake (ADI) for nitrate ions is established by JEFCA as ranging from 0 to 3.7 mg per kilogram of body weight per day.
Which food items are mentioned as significant sources of dietary nitrate for humans?
Answer: Leafy green vegetables and beetroot juice
Explanation: Leafy green vegetables and beetroot juice are identified as major dietary sources of nitrate for human consumption.
How can the formation of potentially carcinogenic nitrosamines during meat curing be reduced?
Answer: By adding antioxidants like Vitamin C
Explanation: The addition of antioxidants, such as Vitamin C, can effectively inhibit the formation of nitrosamines during the meat curing process.
Which symptom is associated with nitrate poisoning in domestic animals?
Answer: Pale blue or brown coloration of blood/tissues
Explanation: A characteristic sign of nitrate poisoning in animals is the cyanotic discoloration (blue or brown) of blood and tissues, indicative of methemoglobinemia.
What is the maximum safe level of nitrate (as %NO₃) in feed for horses, according to the source?
Answer: Less than 1.23%
Explanation: For horses, feed containing less than 1.23% nitrate (dry basis) is generally considered the maximum safe level, with caution advised for pregnant mares.
What is the primary concern regarding nitrate in drinking water, especially for infants?
Answer: It can be converted to nitrite, leading to methemoglobinemia.
Explanation: The principal risk of nitrate in drinking water for infants is its conversion to nitrite, which can cause methemoglobinemia.
Ion chromatography (IC) is the current standard and preferred method for nitrate detection, largely superseding older colorimetric techniques.
Answer: True
Explanation: Ion chromatography (IC) is widely adopted for nitrate analysis due to its efficiency and ability to measure multiple anions simultaneously, surpassing the limitations of older colorimetric methods.
Older colorimetric methods for nitrate detection were often compromised by interference from naturally occurring dissolved organic matter, which could affect absorbance readings.
Answer: True
Explanation: Interference from dissolved organic matter, such as humic acids, was a significant issue with older colorimetric nitrate assays, often requiring sample pretreatment.
The Griess test detects nitrate indirectly by first reducing it to nitrite, which then reacts to form a colored azo dye, not by a direct blue color change.
Answer: True
Explanation: The Griess reaction involves the reduction of nitrate to nitrite, followed by diazotization and coupling to form a red azo dye, which is then measured spectrophotometrically.
The dimethylphenol method involves reacting 2,6-dimethylphenol with nitrate in an acidic medium to produce a yellow compound, which is then quantified spectrophotometrically.
Answer: True
Explanation: In the dimethylphenol method, nitrate reacts with 2,6-dimethylphenol under acidic conditions to form 4-nitro-2,6-dimethylphenol, a yellow product measured spectrophotometrically.
What is the currently preferred and most widely used analytical method for detecting nitrate in water?
Answer: Ion chromatography (IC)
Explanation: Ion chromatography (IC) is the standard and most widely utilized method for analyzing nitrate concentrations in water samples.
What issue did older colorimetric methods for nitrate detection face?
Answer: They were susceptible to interference from dissolved organic matter.
Explanation: Older colorimetric methods for nitrate determination were often affected by interference from dissolved organic matter present in the sample.
How does the Griess test detect nitrate?
Answer: By reducing nitrate to nitrite, then forming a red azo dye.
Explanation: The Griess test detects nitrate indirectly by first converting it to nitrite, which then participates in a reaction forming a red azo dye.
In the dimethylphenol method, what is the product formed when nitrate reacts with 2,6-dimethylphenol?
Answer: A yellow compound, 4-nitro-2,6-dimethylphenol
Explanation: The reaction between nitrate and 2,6-dimethylphenol in the dimethylphenol method yields a yellow compound, 4-nitro-2,6-dimethylphenol.