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Potassium is an alkali metal with the chemical symbol P and an atomic number of 19.
Answer: False
Explanation: Potassium's chemical symbol is K, derived from *kalium*, not P. It is an alkali metal with atomic number 19.
Elemental potassium is a dense, hard metal that maintains its silvery white color even after prolonged exposure to air.
Answer: False
Explanation: Elemental potassium is a soft, silvery-white metal, the second least dense after lithium, and it tarnishes to a gray color immediately upon exposure to air.
Potassium reacts mildly with water, producing hydrogen gas without significant heat generation.
Answer: False
Explanation: Potassium reacts vigorously with water, generating sufficient heat to ignite the produced hydrogen gas, which burns with a distinctive lilac-colored flame.
In nature, potassium is primarily found as a free element due to its low reactivity.
Answer: False
Explanation: Potassium is highly reactive and therefore occurs in nature exclusively as ionic salts, not as a free element.
The chemical behavior of potassium is very similar to that of sodium, both readily losing a single outer electron.
Answer: True
Explanation: Potassium and sodium are both alkali metals in Group 1, sharing similar chemical behaviors, including a low first ionization energy that facilitates the loss of their single outer electron.
The distinction between sodium and potassium salts was first experimentally proven by Humphry Davy in 1807.
Answer: False
Explanation: The experimental distinction between sodium and potassium salts was first demonstrated by Henri Louis Duhamel du Monceau in 1736, predating Humphry Davy's isolation of elemental potassium in 1807.
Humphry Davy isolated elemental potassium using the electrolysis of molten potassium chloride.
Answer: False
Explanation: Humphry Davy first isolated elemental potassium in 1807 through the electrolysis of molten caustic potash (KOH), not potassium chloride.
The English name 'potassium' comes from 'potash,' referring to an early method of extracting potassium salts from plant ashes.
Answer: True
Explanation: The English name 'potassium' is indeed derived from 'potash,' reflecting the historical practice of extracting potassium salts from the ashes of burnt plants.
Potassium compounds emit a distinctive blue color in a flame test, with a peak emission wavelength of 766.5 nanometers.
Answer: False
Explanation: Potassium compounds produce a distinctive lilac color in a flame test, not blue, with a peak emission wavelength of 766.5 nanometers.
A neutral potassium atom has a high first ionization energy, making it difficult to lose its outermost electron.
Answer: False
Explanation: A neutral potassium atom possesses a low first ionization energy, making it prone to readily losing its outermost electron to form a positive ion.
All four well-studied binary potassium-oxygen compounds react with water to form potassium hydroxide (KOH).
Answer: True
Explanation: The four well-studied binary potassium-oxygen compounds—potassium oxide, peroxide, superoxide, and ozonide—all react with water to yield potassium hydroxide (KOH).
Organopotassium compounds are ionic compounds characterized by weak K-C bonds.
Answer: False
Explanation: Organopotassium compounds are nonionic, featuring highly polar covalent K-C bonds, rather than being ionic with weak bonds.
What is the chemical symbol and atomic number for potassium?
Answer: K, 19
Explanation: Potassium is represented by the chemical symbol K, derived from *kalium*, and has an atomic number of 19.
Which of the following accurately describes elemental potassium's density and immediate reaction to air?
Answer: It is the second least dense metal and tarnishes to a gray color immediately upon exposure to air.
Explanation: Elemental potassium is characterized as the second least dense metal and immediately tarnishes to a gray color upon exposure to air.
When potassium metal reacts vigorously with water, what is the characteristic flame color of the ignited hydrogen gas?
Answer: Lilac
Explanation: When potassium metal reacts vigorously with water, the hydrogen gas produced ignites and burns with a distinctive lilac-colored flame.
Which statement about potassium's natural occurrence is accurate?
Answer: It occurs only in ionic salts.
Explanation: Due to its high reactivity, potassium is found in nature exclusively in the form of ionic salts, such as those dissolved in seawater or present in minerals like orthoclase.
In 1736, who experimentally proved the distinction between sodium and potassium salts?
Answer: Henri Louis Duhamel du Monceau
Explanation: Henri Louis Duhamel du Monceau experimentally demonstrated the distinction between sodium and potassium salts in 1736.
What was the method used by Humphry Davy to first isolate elemental potassium in 1807?
Answer: Electrolysis of molten caustic potash (KOH).
Explanation: Humphry Davy first isolated elemental potassium in 1807 through the electrolysis of molten caustic potash (KOH), marking the first metal isolated by this method.
The English name 'potassium' originates from 'potash,' which refers to what historical practice?
Answer: An early method of extracting potassium salts from burnt plant ashes.
Explanation: The English name 'potassium' is derived from 'potash,' a term that refers to the historical method of extracting potassium salts from the ashes of burnt plants.
What is the peak emission wavelength for the distinctive lilac color potassium emits in a flame test?
Answer: 766.5 nanometers
Explanation: Potassium compounds emit a distinctive lilac color in a flame test, with a peak emission wavelength of 766.5 nanometers.
A neutral potassium atom is characterized by which of the following regarding its first ionization energy?
Answer: It is low, making it prone to losing its outermost electron.
Explanation: A neutral potassium atom has a low first ionization energy, which means it readily loses its single outermost electron to form a positive ion.
All four well-studied binary potassium-oxygen compounds react with water to form which common product?
Answer: Potassium hydroxide (KOH)
Explanation: All four well-studied binary potassium-oxygen compounds—potassium oxide, peroxide, superoxide, and ozonide—react with water to form potassium hydroxide (KOH).
Which of these is a common potassium-containing mineral found in large evaporite deposits?
Answer: Sylvite
Explanation: Sylvite (KCl) is a common potassium-containing mineral found in large evaporite deposits worldwide, alongside carnallite, kainite, and langbeinite.
There are 25 known isotopes of potassium, with potassium-39, potassium-40, and potassium-41 occurring naturally.
Answer: True
Explanation: Indeed, 25 isotopes of potassium are known, and potassium-39, potassium-40, and potassium-41 are the three naturally occurring ones.
Potassium-40 primarily decays to stable calcium-40 by electron capture.
Answer: False
Explanation: Potassium-40 primarily decays to stable calcium-40 by beta decay (88.8%), while decay to stable argon-40 occurs via electron capture or positron emission (11.2%).
The K-Ar dating method assumes that rocks contained significant amounts of argon at their formation.
Answer: False
Explanation: The K-Ar dating method relies on the assumption that rocks contained no argon at their formation and have quantitatively retained all subsequent radiogenic argon produced from potassium-40 decay.
How many naturally occurring isotopes does potassium have?
Answer: Three
Explanation: Potassium has three naturally occurring isotopes: potassium-39, potassium-40, and potassium-41.
What is the half-life of naturally occurring potassium-40?
Answer: 1.250 × 10^9 years
Explanation: Naturally occurring potassium-40 has a very long half-life of 1.250 × 10^9 years, making it useful for radiometric dating.
The K-Ar dating method for rocks relies on the decay of potassium-40 into which stable isotope?
Answer: Argon-40
Explanation: The K-Ar dating method is based on the radioactive decay of potassium-40 into stable argon-40, which accumulates in rocks over geological time.
Potassium hydroxide (KOH) is a weak base with low water solubility, limiting its industrial applications.
Answer: False
Explanation: Potassium hydroxide (KOH) is a strong base with high water solubility, making it widely used in various industrial applications such as neutralizing acids and saponifying fats.
Potash was historically used for producing glass, bleach, soap, and gunpowder.
Answer: True
Explanation: Historically, potash, a mixture of potassium salts, was widely utilized in the production of glass, bleach, soap, and gunpowder (as potassium nitrate).
Justus Liebig's discovery in 1840 that potassium is essential for plant growth led to a decrease in demand for potassium salts.
Answer: False
Explanation: Justus Liebig's 1840 discovery of potassium's essential role in plant growth, coupled with its common deficiency in soil, actually led to a significant increase in demand for potassium salts for agricultural fertilizers.
The first industrial-scale potassium-containing fertilizer deposits were discovered in Canada in 1868.
Answer: False
Explanation: The first industrial-scale potassium-containing fertilizer deposits were discovered near Staßfurt, Germany, in 1868, not in Canada.
Pure potassium metal is currently extracted primarily by electrolysis of its hydroxide, as first demonstrated by Humphry Davy.
Answer: False
Explanation: While Humphry Davy first isolated potassium by electrolysis of its hydroxide, the dominant method for chemical extraction in the 1950s was the thermal reaction of sodium with potassium chloride, which remains a significant industrial route.
Gravimetric analysis using reagents like sodium tetraphenylborate is the primary modern method for quantifying potassium in analytical chemistry.
Answer: False
Explanation: While gravimetric analysis was historically used, modern analytical chemistry primarily quantifies potassium using ionization techniques, not gravimetric methods.
The vast majority of commercially produced potassium chemicals are used in agricultural fertilizers.
Answer: True
Explanation: Agricultural fertilizers account for 95% of the global commercial use of potassium chemicals, making it their predominant application.
Potassium chloride (KCl) is the most common form of potassium supplied as fertilizer, making up about 90% of the total.
Answer: True
Explanation: Potassium chloride (KCl) is indeed the most widely used potassium fertilizer, constituting approximately 90% of the total potassium supplied for agricultural purposes.
Potassium superoxide (KO2) is used in respiration systems because it absorbs oxygen and releases carbon dioxide.
Answer: False
Explanation: Potassium superoxide (KO2) is used in respiration systems because it absorbs carbon dioxide and simultaneously releases oxygen, acting as a portable oxygen source and CO2 scrubber.
Which of the following is a primary industrial use of potassium hydroxide (KOH)?
Answer: Neutralizing acids and saponifying fats and oils.
Explanation: Potassium hydroxide (KOH) is a strong base widely used industrially for neutralizing acids, controlling pH, and saponifying fats and oils.
What discovery in 1840 significantly increased the demand for potassium salts for agricultural fertilizers?
Answer: Justus Liebig's finding that potassium is essential for plant growth and often deficient in soil.
Explanation: Justus Liebig's discovery in 1840 that potassium is essential for plant growth and commonly deficient in soil dramatically increased the demand for potassium salts in agricultural fertilizers.
Where were the first industrial-scale potassium-containing fertilizer deposits discovered in 1868?
Answer: Staßfurt, Germany
Explanation: The first industrial-scale potassium-containing fertilizer deposits were discovered near Staßfurt, Germany, in 1868, leading to the beginning of large-scale production.
What was the dominant method for chemically extracting pure potassium metal in the 1950s?
Answer: Thermal reaction of sodium with potassium chloride.
Explanation: In the 1950s, the dominant method for chemically extracting pure potassium metal was the thermal reaction of sodium with potassium chloride, a chemical equilibrium reaction.
What accounts for 95% of the global commercial use of potassium chemicals?
Answer: Agricultural fertilizers.
Explanation: Agricultural fertilizers constitute 95% of the global commercial use of potassium chemicals, highlighting their critical role in plant nutrition.
Which form of potassium is the most common agricultural fertilizer, making up about 90% of the potassium supplied?
Answer: Potassium chloride (KCl)
Explanation: Potassium chloride (KCl) is the most prevalent form of potassium used as an agricultural fertilizer, accounting for approximately 90% of the total potassium supplied.
Potassium superoxide (KO2) is used in respiration systems in mines, submarines, and spacecraft for what primary function?
Answer: As a portable source of oxygen and a carbon dioxide absorber.
Explanation: Potassium superoxide (KO2) serves a crucial function in respiration systems by acting as a portable oxygen source and an efficient carbon dioxide absorber.
Potassium-40 is the most common radioisotope found in the human body and is the largest source of internal radioactivity in healthy individuals.
Answer: True
Explanation: Potassium-40 is indeed the most prevalent radioisotope in the human body and constitutes the largest source of internal radioactivity in healthy individuals.
Potassium is the most abundant element by mass in the human body, making up about 10% of an adult's body weight.
Answer: False
Explanation: Potassium is the eighth or ninth most common element by mass in the human body, constituting approximately 0.2% of an adult's body weight, not 10%.
The sodium-potassium pump actively transports three potassium ions out of the cell and two sodium ions into the cell.
Answer: False
Explanation: The sodium-potassium pump (Na+/K+-ATPase) actively transports three sodium ions out of the cell and two potassium ions into the cell, utilizing ATP to maintain electrochemical gradients.
Normal plasma potassium levels are typically maintained between 3.5 to 5.5 millimoles per liter.
Answer: True
Explanation: Normal plasma potassium levels are indeed tightly regulated and typically fall within the range of 3.5 to 5.5 millimoles (or milliequivalents) per liter.
The reactive negative-feedback system for potassium regulation increases renal secretion in response to a rise in plasma potassium levels.
Answer: True
Explanation: The reactive negative-feedback system effectively regulates potassium by increasing renal secretion when plasma potassium levels rise, thereby maintaining homeostasis.
The predictive or circadian system for potassium regulation increases renal secretion during typical mealtime hours, regardless of actual potassium intake.
Answer: True
Explanation: The predictive or circadian system for potassium regulation indeed increases renal secretion during typical mealtime hours, a mechanism mediated by the brain's suprachiasmatic nucleus, independent of immediate potassium intake.
In the kidneys, potassium is filtered once and then fully reabsorbed before excretion.
Answer: False
Explanation: Kidney handling of potassium is complex, involving filtration, reabsorption, excretion twice, reabsorption three times, and potential re-secretion in the collecting tubules if serum levels are too high.
What is the significance of potassium-40 in the human body?
Answer: It is the most common radioisotope and the largest source of internal radioactivity.
Explanation: Potassium-40 is notable in the human body as the most common radioisotope and the largest contributor to internal radioactivity in healthy individuals.
Approximately what percentage of an adult's body weight is composed of potassium?
Answer: 0.2%
Explanation: Potassium constitutes approximately 0.2% of an adult's body weight, making it the eighth or ninth most common element by mass in the human body.
The sodium-potassium pump (Na+/K+-ATPase) actively transports how many sodium and potassium ions, and in which direction?
Answer: Three sodium ions out and two potassium ions into the cell.
Explanation: The sodium-potassium pump actively transports three sodium ions out of the cell and two potassium ions into the cell, a process vital for maintaining cellular electrochemical gradients.
What is the normal range for plasma potassium levels in millimoles (mmol) or milliequivalents (mEq) per liter?
Answer: 3.5 to 5.5
Explanation: Normal plasma potassium levels are maintained within a narrow range of 3.5 to 5.5 millimoles (or milliequivalents) per liter, crucial for overall physiological function.
The predictive or circadian system for potassium regulation is mediated by a central circadian oscillator in the brain's suprachiasmatic nucleus, which signals the kidney to do what?
Answer: Secrete potassium rhythmically during typical mealtime hours.
Explanation: The predictive or circadian system, controlled by the brain's suprachiasmatic nucleus, signals the kidney to rhythmically secrete potassium during typical mealtime hours, anticipating dietary intake.
Potassium citrate is used to treat low blood potassium, while potassium chloride treats kidney stones.
Answer: False
Explanation: Potassium citrate is used to treat renal tubular acidosis, a kidney stone condition, whereas potassium chloride is administered to treat and prevent low blood potassium (hypokalemia).
Hypokalemia is a condition characterized by an excess of potassium in the plasma, often leading to muscle cramps and fatigue.
Answer: False
Explanation: Hypokalemia is defined as a deficiency of potassium in the plasma, not an excess. Its symptoms include muscle weakness, cramps, and fatigue.
The Adequate Intake (AI) for potassium for adult males 19 years and older in North America is 2,600 mg.
Answer: False
Explanation: The Adequate Intake (AI) for potassium for adult males 19 years and older in North America is 3,400 mg, while 2,600 mg is the AI for adult females in the same age group.
Non-prescription potassium pills in the U.S. are limited to 99 mg of potassium to prevent hyperkalemia from a single dose.
Answer: False
Explanation: Non-prescription potassium pills in the U.S. are limited to 99 mg of potassium primarily to prevent localized gastric or intestinal mucosal injury and potential ulcers, rather than to prevent systemic hyperkalemia from a single dose.
Potassium supplementation can help lower blood pressure in individuals with essential hypertension.
Answer: True
Explanation: Potassium supplementation, particularly with potassium chloride and potassium bicarbonate, has been shown to effectively lower both systolic and diastolic blood pressure in individuals with essential hypertension, thereby reducing cardiovascular risk.
Low potassium levels can increase the risk of kidney stone formation by decreasing calcium reabsorption in the kidneys.
Answer: True
Explanation: Low potassium levels can indeed increase the risk of kidney stone formation by leading to decreased calcium reabsorption in the kidneys, which subsequently elevates urine calcium concentrations.
Excessive potassium intake or supplementation can lead to adverse effects such as gastrointestinal discomfort and hyperkalemia.
Answer: True
Explanation: Excessive intake or supplementation of potassium can result in adverse effects including gastrointestinal discomfort, disturbances in heart rhythm (hyperkalemia), and an increased risk of gastric ulcers.
Dilute solutions of potassium taste salty, while higher concentrations taste sweet.
Answer: False
Explanation: Potassium's taste profile is complex: dilute solutions are sweet, higher concentrations become bitter/alkaline, and finally salty, making high-dose liquid supplements challenging to consume.
Potassium chloride is used in lethal injection executions because it causes fatal brady- and tachy-arrhythmias.
Answer: True
Explanation: Potassium chloride is utilized in lethal injection executions because the resulting hyperkalemia (excess potassium in the blood) induces fatal brady- and tachy-arrhythmias, leading to cardiac arrest.
Potassium citrate is medically used to treat which specific condition?
Answer: Renal tubular acidosis, a kidney stone condition.
Explanation: Potassium citrate is medically prescribed to treat renal tubular acidosis, a condition associated with kidney stone formation.
Which of the following is a common cause of hypokalemia?
Answer: Increased gastrointestinal loss (vomiting, diarrhea).
Explanation: Common causes of hypokalemia, a deficiency of plasma potassium, include increased gastrointestinal losses from vomiting or diarrhea, as well as increased renal loss or certain medications.
For adult females 19 years of age and older in North America, what is the Adequate Intake (AI) for potassium?
Answer: 2,600 mg
Explanation: The Adequate Intake (AI) for potassium for adult females 19 years and older in North America is 2,600 mg, while for males it is 3,400 mg.
The palatability challenge of high-dose liquid potassium supplements is primarily due to potassium triggering which taste sensations at higher concentrations?
Answer: A combination of bitterness/alkalinity and saltiness.
Explanation: High-dose liquid potassium supplements are often unpalatable because higher concentrations of potassium trigger both bitter/alkaline and salty taste sensations.
Low potassium levels can increase the risk of kidney stone formation by causing what effect in the kidneys?
Answer: Decreased calcium reabsorption, leading to increased urine calcium.
Explanation: Low potassium levels can increase the risk of kidney stone formation by decreasing calcium reabsorption in the kidneys, which subsequently elevates urine calcium concentrations.
Which of the following is an adverse effect of excessive potassium intake or supplementation?
Answer: Hyperkalemia
Explanation: Excessive potassium intake or supplementation can lead to hyperkalemia, a potentially dangerous condition characterized by elevated potassium levels in the blood, along with gastrointestinal discomfort and an increased risk of gastric ulcers.
The use of potassium chloride in lethal injection executions is due to the fact that hyperkalemia can lead to what?
Answer: Fatal brady- and tachy-arrhythmias.
Explanation: Potassium chloride is used in lethal injection executions because the resulting hyperkalemia induces fatal brady- and tachy-arrhythmias, causing the heart to stop.
Potassium metal should be stored under water to prevent the formation of explosive potassium superoxide.
Answer: False
Explanation: Potassium metal must be stored under a dry inert gas atmosphere or anhydrous mineral oil to prevent reaction with oxygen and water, as it reacts violently with water and forms explosive potassium superoxide upon air exposure.
Potassium is classified with GHS pictograms indicating flammability and corrosivity.
Answer: True
Explanation: Under the Globally Harmonized System (GHS), potassium is indeed classified with pictograms denoting flammability and corrosivity, reflecting its hazardous nature.
Water is an effective extinguishing agent for potassium fires.
Answer: False
Explanation: Water is explicitly ineffective and can worsen potassium fires due to potassium's violent reaction with it, which produces flammable hydrogen gas. Specialized Class D dry powder extinguishers are required.
To prevent the formation of potassium superoxide, which is a pressure-sensitive explosive, how must potassium metal be stored?
Answer: In a dry inert gas atmosphere or under anhydrous mineral oil.
Explanation: Potassium metal must be stored in a dry inert gas atmosphere or under anhydrous mineral oil or kerosene to prevent the formation of explosive potassium superoxide, which can detonate upon scratching.
Which common extinguishing agent is explicitly stated as ineffective or worsening a potassium fire?
Answer: Water
Explanation: Water is explicitly stated as an ineffective or fire-worsening agent for potassium fires due to potassium's violent reaction with it, which produces flammable hydrogen gas.