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An alkali is fundamentally defined in chemistry as a basic salt of an alkali metal or an alkaline earth metal, or more broadly as any base that dissolves in water.
Answer: True
Explanation: The definition of an alkali encompasses basic salts of alkali or alkaline earth metals, and more broadly, any water-soluble base.
The word 'alkali' originates from a Greek term meaning 'strong base'.
Answer: False
Explanation: The term 'alkali' is derived from the Arabic 'al qaly', meaning 'the calcined ashes', referring to its historical source from plant ashes, not a Greek term for 'strong base'.
Chemists often use 'base' and 'alkali' interchangeably without any specific differentiation.
Answer: False
Explanation: Chemists differentiate between 'base' and 'alkali', with alkalis being a specific subset of bases, often defined by solubility or metal composition, even if the terms are used interchangeably in common parlance.
The adjective 'alkalescent' is less frequently used than 'alkaline' as a synonym for basic, especially for water-soluble bases.
Answer: True
Explanation: The text states that 'alkalescent' is indeed less frequently used than 'alkaline' as a synonym for basic, particularly for water-soluble bases.
The broad use of 'alkaline' as a synonym for 'basic' is because alkalis were the first bases known to conform to the Arrhenius definition.
Answer: True
Explanation: The widespread use of 'alkaline' as a synonym for 'basic' is attributed to alkalis being the initial bases identified that aligned with the Arrhenius definition.
According to the source, what is one fundamental definition of an alkali in chemistry?
Answer: A basic salt of an alkali metal or an alkaline earth metal.
How do chemists commonly differentiate 'alkali' from 'base'?
Answer: Alkalis are a specific subset of bases, often defined by solubility or metal composition.
What does the Arabic term 'al qaly' or 'alkali' translate to?
Answer: The calcined ashes
What is the broader definition of an alkali in relation to bases?
Answer: Any base that dissolves in water.
Potash, an early alkaline substance, was primarily composed of sodium carbonate.
Answer: False
Explanation: Potash was primarily composed of potassium carbonate, not sodium carbonate.
Caustic potash was traditionally used with animal fats to produce hard soaps through a process called saponification.
Answer: False
Explanation: Caustic potash was traditionally used to produce soft soaps, not hard soaps, through saponification.
The chemical symbol for potassium, 'K', is derived from its German name 'Kalium'.
Answer: True
Explanation: The chemical symbol 'K' for potassium indeed originates from its German name 'Kalium', which itself is derived from 'alkali'.
Slaked lime is chemically known as calcium carbonate.
Answer: False
Explanation: Slaked lime is chemically known as calcium hydroxide, not calcium carbonate.
Potassium was first derived from caustic soda.
Answer: False
Explanation: Potassium was first derived from caustic potash, not caustic soda.
The process of saponification converts fats into soap and is a relatively recent chemical discovery.
Answer: False
Explanation: Saponification, the process of converting fats into soap, has been known since antiquity, making it a very old chemical process, not a recent discovery.
What was potash, an early alkaline substance, primarily composed of?
Answer: Potassium carbonate
What was the traditional use of caustic potash?
Answer: To produce soft soaps with animal fats.
What is the origin of potassium's chemical symbol 'K'?
Answer: Its German name 'Kalium'.
How was caustic potash produced from potash?
Answer: By heating potash with calcium hydroxide.
All Arrhenius bases are considered alkalis.
Answer: False
Explanation: While all alkalis are Arrhenius bases, not all Arrhenius bases are alkalis. For example, ammonia is an Arrhenius base but not typically classified as an alkali.
Moderately concentrated alkaline aqueous solutions typically have a pH of 10 or greater.
Answer: True
Explanation: Moderately concentrated alkaline solutions are indeed characterized by a pH value of 10 or higher.
Phenolphthalein turns blue in the presence of a moderately concentrated alkaline solution.
Answer: False
Explanation: Phenolphthalein turns pink, not blue, in the presence of a moderately concentrated alkaline solution.
Concentrated alkaline solutions are caustic and can cause chemical burns.
Answer: True
Explanation: Concentrated alkaline solutions are indeed caustic and can cause chemical burns due to their corrosive nature.
The slippery sensation when touching alkaline solutions is due to their reaction with skin proteins.
Answer: False
Explanation: The slippery sensation is caused by the saponification of fatty substances on the skin's surface, not a reaction with skin proteins.
All alkalis are water-soluble without exception.
Answer: False
Explanation: While most alkalis are water-soluble, there are exceptions, such as barium carbonate, which only dissolves when reacting with an acidic aqueous solution.
A solution of a soluble base will have a pH less than 7.0, indicating its acidic nature.
Answer: False
Explanation: A solution of a soluble base (an alkali) will have a pH greater than 7.0, indicating its basic nature.
When alkalis dissolve in water, they form hydrogen ions (H⁺).
Answer: False
Explanation: When alkalis dissolve in water, they form hydroxide ions (OH⁻), which is characteristic of Arrhenius bases, not hydrogen ions.
The pH of an alkaline solution is always exactly 7.0.
Answer: False
Explanation: An alkaline solution has a pH greater than 7.0; a pH of exactly 7.0 indicates a neutral solution.
What happens when alkalis are dissolved in water, making them Arrhenius bases?
Answer: They form hydroxide ions (OH⁻).
Which of the following is a common property of moderately concentrated alkaline aqueous solutions?
Answer: They feel slippery or soapy to the touch.
What is the typical pH range for moderately concentrated alkaline solutions?
Answer: 10 or greater
What visual change does phenolphthalein undergo in an alkaline solution?
Answer: Turns colorless to pink
Why do concentrated alkaline solutions cause chemical burns?
Answer: They are caustic substances.
What causes the slippery or soapy sensation when touching alkaline solutions?
Answer: The saponification of fatty substances on the skin.
Which of the following alkalis is mentioned as an exception to general water solubility, dissolving only when reacting with an acidic aqueous solution?
Answer: Barium carbonate
What is the significance of a solution having a pH greater than 7.0 in relation to alkalis?
Answer: It indicates the solution is basic.
Lye is a generic term specifically for sodium hydroxide.
Answer: False
Explanation: Lye is a generic term that can refer to sodium hydroxide, potassium hydroxide, or a mixture of both.
Magnesium hydroxide is considered a typical alkali due to its high solubility in water.
Answer: False
Explanation: Magnesium hydroxide is considered an atypical alkali precisely because of its low solubility in water, despite its dissolved portion being a strong base.
Sodium hydroxide is commonly known as 'caustic potash'.
Answer: False
Explanation: Sodium hydroxide is commonly known as 'caustic soda', whereas 'caustic potash' refers to potassium hydroxide.
The saturated solution of calcium hydroxide is known as 'limewater'.
Answer: True
Explanation: The saturated solution of calcium hydroxide is indeed referred to as 'limewater'.
The chemical formula for potassium hydroxide is NaOH.
Answer: False
Explanation: The chemical formula for potassium hydroxide is KOH, while NaOH is the formula for sodium hydroxide.
Why is magnesium hydroxide considered an atypical alkali?
Answer: It has low solubility in water.
What is 'lye' a generic term for?
Answer: Sodium hydroxide, potassium hydroxide, or a mixture of the two.
Soils are defined as alkaline if their pH values are higher than 7.3.
Answer: True
Explanation: Alkaline soil is indeed defined by a pH value exceeding 7.3.
Most plants prefer highly alkaline soil conditions for optimal growth.
Answer: False
Explanation: Most plants prefer mildly acidic soil (pH 6.0-6.8) for optimal growth, not highly alkaline conditions.
An alkali lake forms when evaporation concentrates naturally occurring sulfate salts.
Answer: False
Explanation: Alkali lakes form due to the concentration of naturally occurring carbonate salts, not sulfate salts, through evaporation.
Lake Magadi and Lake Turkana are examples of alkali lakes found in Kenya.
Answer: True
Explanation: The text explicitly lists Lake Magadi and Lake Turkana in Kenya as examples of alkali lakes.
Cabbage and buffalo grass are examples of plants that prefer slightly basic soil.
Answer: True
Explanation: The text specifically mentions cabbage and buffalo grass as plants that prefer slightly basic soil conditions.
Alkali lakes are also commonly referred to as salt lakes.
Answer: False
Explanation: Alkali lakes are also commonly referred to as soda lakes, not salt lakes, although they can be saline.
Baldwin Lake in San Bernardino County, California, is cited as an example of an alkali lake.
Answer: True
Explanation: Baldwin Lake is indeed listed as an example of an alkali lake in the provided text.
Which of the following lakes is mentioned as an example of an alkali lake?
Answer: Mono Lake
What is the general pH preference for most plants regarding soil conditions?
Answer: Mildly acidic (pH 6.0-6.8)
Which of the following plants is mentioned as preferring slightly basic soil?
Answer: Cabbage
What type of salts are concentrated in an alkali lake due to evaporation?
Answer: Carbonate salts
Which of the following is NOT an example of an alkali lake mentioned in the text?
Answer: Lake Victoria in Africa