Project Number: 2023-1-PL01-KA220-SCH-000164042
UNIT 10: Acids and Bases
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Education and Culture Executive Agency (EACEA). Neither the European Union nor EACEA can be held responsible for them.
Introduction
In this activity, you will learn about acids and bases and the concept of pH, which we encounter in many places in our daily lives.
Source: canva.com
Learning Outcomes
1- Students express the general properties of acids and bases. 2- Students give examples of acids and bases from daily life. 3- Students make inferences about the acidity and alkalinity of substances by using pH values.
An interesting discovery: Hydrothermal vents
Hydrothermal vents were discovered by chance in 1977 by a group of scientists from the United States during a seafloor survey off the Galápagos Islands in the Pacific Ocean.
Source: canva.com
An interesting discovery: Hydrothermal vents
Their main objective was to study the joints of tectonic plates on the seafloor. But during the dive, they unexpectedly discovered streams of warm, mineral-rich water emerging from the seafloor at a depth of 2,500 meters.
Source: canva.com
An interesting discovery: Hydrothermal vents
Ocean water, heated by magma seeping through crevices in the ocean floor, carries metal ions and other minerals from the magma to the ocean floor. The accumulation of these minerals over time forms hydrothermal vents.
Source: canva.com
An interesting discovery: Hydrothermal vents
With the effect of hot water rising from the magma, the temperature can reach 350-400oC inside the chimney and 100oC at the mouth of the chimney.
Source: canva.com
An interesting discovery: Hydrothermal vents
Generally, black or white colored smoke is observed from the chimneys. While black smoke contains high amounts of sulfur minerals, white smoke contains light colored minerals such as barium, calcium and silicon. This makes the ambient conditions very challenging for life, both in terms of temperature and acidity.
Source: canva.com
An interesting discovery: Hydrothermal vents
However, contrary to expectations, many species have been observed that have adapted to these harsh conditions. Some of them are even known to be endemic, meaning that they can only survive in the region where hydrothermal vents are located on Earth.
Source: canva.com
An interesting discovery: Hydrothermal vents
It may seem strange that we would choose to live in such a harsh place when there are so many other places on Earth where conditions are more favorable. But who knows: maybe our living conditions are similarly challenging for thosecreatures.
Source: canva.com
An interesting discovery: Hydrothermal vents
For example, if any of you are interested in flowers, you will know that some flowers donot grow in all soils, they need their own special soil. As in the case of hydrothermal vents, in our flower growing example, acidity-basicity is an important parameter for vital activities. So let's take a closer look at acids and bases, which are vital for life:
Source: canva.com
What are Acids and Bases?
The concepts of acids, bases and pH are very important in our understanding of chemical substances. Acids and bases have been defined in different ways throughout history. Acids are usually known for their sour taste, while bases are known for their bitter taste. Also, acids turn litmus paper red, while bases turn it blue.
What are Acids and Bases?
However, since tasting every chemical can be dangerous, it is necessary to use safer and more detailed methods of analysis to determine whether a substance is acidic or basic. If you look at science books, you will see that there are different definitions of acid and base.
Source: canva.com
What are Acids and Bases?
One of the most common is the Arrhenius acid-base definition developed by the Swedish scientist Svante Arrhenius. According to this definition, substances that give off hydrogen ions (H+) when dissociated are acids and substances that give off hydroxyl ions (OH-) are bases.
Source: canva.com
What are Acids and Bases?
Although this definition is still used, it may be insufficient in some cases. Because according to this definition, for a substance to be acidic, it must have hydrogen in its structure, and for it to be basic, it must have a hydroxyl group.
Source: canva.com
What are Acids and Bases?
However, there are substances that do not contain OH- in their structure but still exhibit basic properties. One of the best examples is NH₃. The compound NH₃ (ammonia) has basic properties even though it does not contain OH- ions.
Source: canva.com
What are Acids and Bases?
Another definition of acids and bases is the Brönsted-Lowry Definition. This definition is based on an acid-base reaction theory created independently by Johannes Nicolaus Brønsted and Thomas Martin Lowry.
Source: canva.com
What are Acids and Bases?
According to this theory, substances that give (H+) ions when they dissociate are acids and those that can receive them are bases. Acids give hydrogen ions (H+) and turn into their own base. Bases, on the other hand, take hydrogen ions (H+) and turn into their own acid. Although water is actually neutral, it is known that it can show acidic or basic properties depending on whether the substance it interacts with is acid or base.
Source: canva.com
What are Acids and Bases?
When water interacts with acid, it shows base; when it interacts with base, it shows acidic properties. Because of this property, water is defined as an amphoteric substance. While Arrhenius definition is insufficient to explain these amphoteric substances, Brönsted-Lowry definition can explain these substances.
Source: canva.com
The Place of Acids and Bases in Our Lives
When we think of acids and bases, many people think of the dangerous chemicals they learned about in science class, stored in locked cabinets in the laboratory.
The Place of Acids and Bases in Our Lives
Especially acids may evoke danger for many people. However, acids and bases are found in many places in our daily lives. Examples of acids in our daily lives are citric acid, which is found in oranges, lemons, vinegar and many foodstuffs. As you can see, they all fit Arrhenius' definition of acid.
Source: canva.com
The Place of Acids and Bases in Our Lives
Base rise is mostly found in cleaning products. Soaps, bleach, toothpaste, washing soda (sodium bicarbonate) are base materials that we frequently use in daily life.
Source: canva.com
The Place of Acids and Bases in Our Lives
Another reflection of acids and bases in our daily lives is salts. Salts are formed when acids and bases combine and neutralize each other. Therefore, in laboratories, if you get splashed with acid during an experiment, it is recommended that you wash it off first with plenty of water and then with plenty of soap.
Source: canva.com
The Place of Acids and Bases in Our Lives
Acid + Base = Salt + Water HCl + NaOH = NaCl + H2O
For example, we use toothpaste, which is a base, to prevent the acids in the food we eat from damaging our teeth. But in toothpaste we do not use the very strong bases used in laboratories, which have an irritating effect.
Source: canva.com
The Place of Acids and Bases in Our Lives
Therefore, it is not enough to classify substances as acids and bases. Analytical methods are needed to determine the strength of acids and bases. At this point, we come across the concept of "pH" or "power of hydrogen". Let's take a closer look at the concept of pH.
Source: canva.com
The concept of pH
The pH concept is a measure of the acidity or basicity of a substance. The pH scale gives us clear information to determine whether a substance is acidic or basic.
Source: canva.com
The concept of pH
According to this scale, if the pH value is less than 7, the substance is acidic; if it is greater than 7, it is basic; and if it is 7, it is neutral. The pH value of a substance directly depends on the ratio of hydrogen ion [H+] and hydroxyl ion [OH-] concentrations.
Source: canva.com
The concept of pH
If the concentration of H+ is higher than the concentration of OH-, our substance is acidic; that is, the pH value is lower than 7. If the concentration of OH- is higher than the concentration of H+, our substance is basic; that is, the pH value is greater than 7.
Source: canva.com
The concept of pH
If equal amounts of OH- and H+ ions are present, the substance is neutral with a pH of 7.
Source: canva.com
The concept of pH
For example, pure water (pH=7) is an example of a neutral substance. As the pH value approaches 0, the substance becomes more acidic and as it approaches 14, it becomes more basic.
Source: canva.com
The concept of pH
CAUTION: Strong bases with high pH can be as dangerous as strong acids. For this reason, it is very important to know the pH of the chemical to be used.
Source: canva.com
LEARNING ACTIVITY:
In this activity, you are asked to decide whether the chemicals in the augmented reality environment are acids or bases,and then rank them according to their pH levels from weak to strong.
LEARNING ACTIVITY:
Why do you think different indicators are needed when determining pH? .............................................................................................................................................................................................................................................................................................................................. How did you choose the indicators during the activity? .............................................................................................................................................................................................................................................................................................................................. Briefly explain the concept and importance of pH in the light of what you have learned in this unit. ..............................................................................................................................................................................................................................................................................................................................
UNIT 10: Acids and Bases
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Transcript
Project Number: 2023-1-PL01-KA220-SCH-000164042
UNIT 10: Acids and Bases
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Education and Culture Executive Agency (EACEA). Neither the European Union nor EACEA can be held responsible for them.
Introduction
In this activity, you will learn about acids and bases and the concept of pH, which we encounter in many places in our daily lives.
Source: canva.com
Learning Outcomes
1- Students express the general properties of acids and bases. 2- Students give examples of acids and bases from daily life. 3- Students make inferences about the acidity and alkalinity of substances by using pH values.
An interesting discovery: Hydrothermal vents
Hydrothermal vents were discovered by chance in 1977 by a group of scientists from the United States during a seafloor survey off the Galápagos Islands in the Pacific Ocean.
Source: canva.com
An interesting discovery: Hydrothermal vents
Their main objective was to study the joints of tectonic plates on the seafloor. But during the dive, they unexpectedly discovered streams of warm, mineral-rich water emerging from the seafloor at a depth of 2,500 meters.
Source: canva.com
An interesting discovery: Hydrothermal vents
Ocean water, heated by magma seeping through crevices in the ocean floor, carries metal ions and other minerals from the magma to the ocean floor. The accumulation of these minerals over time forms hydrothermal vents.
Source: canva.com
An interesting discovery: Hydrothermal vents
With the effect of hot water rising from the magma, the temperature can reach 350-400oC inside the chimney and 100oC at the mouth of the chimney.
Source: canva.com
An interesting discovery: Hydrothermal vents
Generally, black or white colored smoke is observed from the chimneys. While black smoke contains high amounts of sulfur minerals, white smoke contains light colored minerals such as barium, calcium and silicon. This makes the ambient conditions very challenging for life, both in terms of temperature and acidity.
Source: canva.com
An interesting discovery: Hydrothermal vents
However, contrary to expectations, many species have been observed that have adapted to these harsh conditions. Some of them are even known to be endemic, meaning that they can only survive in the region where hydrothermal vents are located on Earth.
Source: canva.com
An interesting discovery: Hydrothermal vents
It may seem strange that we would choose to live in such a harsh place when there are so many other places on Earth where conditions are more favorable. But who knows: maybe our living conditions are similarly challenging for thosecreatures.
Source: canva.com
An interesting discovery: Hydrothermal vents
For example, if any of you are interested in flowers, you will know that some flowers donot grow in all soils, they need their own special soil. As in the case of hydrothermal vents, in our flower growing example, acidity-basicity is an important parameter for vital activities. So let's take a closer look at acids and bases, which are vital for life:
Source: canva.com
What are Acids and Bases?
The concepts of acids, bases and pH are very important in our understanding of chemical substances. Acids and bases have been defined in different ways throughout history. Acids are usually known for their sour taste, while bases are known for their bitter taste. Also, acids turn litmus paper red, while bases turn it blue.
What are Acids and Bases?
However, since tasting every chemical can be dangerous, it is necessary to use safer and more detailed methods of analysis to determine whether a substance is acidic or basic. If you look at science books, you will see that there are different definitions of acid and base.
Source: canva.com
What are Acids and Bases?
One of the most common is the Arrhenius acid-base definition developed by the Swedish scientist Svante Arrhenius. According to this definition, substances that give off hydrogen ions (H+) when dissociated are acids and substances that give off hydroxyl ions (OH-) are bases.
Source: canva.com
What are Acids and Bases?
Although this definition is still used, it may be insufficient in some cases. Because according to this definition, for a substance to be acidic, it must have hydrogen in its structure, and for it to be basic, it must have a hydroxyl group.
Source: canva.com
What are Acids and Bases?
However, there are substances that do not contain OH- in their structure but still exhibit basic properties. One of the best examples is NH₃. The compound NH₃ (ammonia) has basic properties even though it does not contain OH- ions.
Source: canva.com
What are Acids and Bases?
Another definition of acids and bases is the Brönsted-Lowry Definition. This definition is based on an acid-base reaction theory created independently by Johannes Nicolaus Brønsted and Thomas Martin Lowry.
Source: canva.com
What are Acids and Bases?
According to this theory, substances that give (H+) ions when they dissociate are acids and those that can receive them are bases. Acids give hydrogen ions (H+) and turn into their own base. Bases, on the other hand, take hydrogen ions (H+) and turn into their own acid. Although water is actually neutral, it is known that it can show acidic or basic properties depending on whether the substance it interacts with is acid or base.
Source: canva.com
What are Acids and Bases?
When water interacts with acid, it shows base; when it interacts with base, it shows acidic properties. Because of this property, water is defined as an amphoteric substance. While Arrhenius definition is insufficient to explain these amphoteric substances, Brönsted-Lowry definition can explain these substances.
Source: canva.com
The Place of Acids and Bases in Our Lives
When we think of acids and bases, many people think of the dangerous chemicals they learned about in science class, stored in locked cabinets in the laboratory.
The Place of Acids and Bases in Our Lives
Especially acids may evoke danger for many people. However, acids and bases are found in many places in our daily lives. Examples of acids in our daily lives are citric acid, which is found in oranges, lemons, vinegar and many foodstuffs. As you can see, they all fit Arrhenius' definition of acid.
Source: canva.com
The Place of Acids and Bases in Our Lives
Base rise is mostly found in cleaning products. Soaps, bleach, toothpaste, washing soda (sodium bicarbonate) are base materials that we frequently use in daily life.
Source: canva.com
The Place of Acids and Bases in Our Lives
Another reflection of acids and bases in our daily lives is salts. Salts are formed when acids and bases combine and neutralize each other. Therefore, in laboratories, if you get splashed with acid during an experiment, it is recommended that you wash it off first with plenty of water and then with plenty of soap.
Source: canva.com
The Place of Acids and Bases in Our Lives
Acid + Base = Salt + Water HCl + NaOH = NaCl + H2O
For example, we use toothpaste, which is a base, to prevent the acids in the food we eat from damaging our teeth. But in toothpaste we do not use the very strong bases used in laboratories, which have an irritating effect.
Source: canva.com
The Place of Acids and Bases in Our Lives
Therefore, it is not enough to classify substances as acids and bases. Analytical methods are needed to determine the strength of acids and bases. At this point, we come across the concept of "pH" or "power of hydrogen". Let's take a closer look at the concept of pH.
Source: canva.com
The concept of pH
The pH concept is a measure of the acidity or basicity of a substance. The pH scale gives us clear information to determine whether a substance is acidic or basic.
Source: canva.com
The concept of pH
According to this scale, if the pH value is less than 7, the substance is acidic; if it is greater than 7, it is basic; and if it is 7, it is neutral. The pH value of a substance directly depends on the ratio of hydrogen ion [H+] and hydroxyl ion [OH-] concentrations.
Source: canva.com
The concept of pH
If the concentration of H+ is higher than the concentration of OH-, our substance is acidic; that is, the pH value is lower than 7. If the concentration of OH- is higher than the concentration of H+, our substance is basic; that is, the pH value is greater than 7.
Source: canva.com
The concept of pH
If equal amounts of OH- and H+ ions are present, the substance is neutral with a pH of 7.
Source: canva.com
The concept of pH
For example, pure water (pH=7) is an example of a neutral substance. As the pH value approaches 0, the substance becomes more acidic and as it approaches 14, it becomes more basic.
Source: canva.com
The concept of pH
CAUTION: Strong bases with high pH can be as dangerous as strong acids. For this reason, it is very important to know the pH of the chemical to be used.
Source: canva.com
LEARNING ACTIVITY:
In this activity, you are asked to decide whether the chemicals in the augmented reality environment are acids or bases,and then rank them according to their pH levels from weak to strong.
LEARNING ACTIVITY:
Why do you think different indicators are needed when determining pH? .............................................................................................................................................................................................................................................................................................................................. How did you choose the indicators during the activity? .............................................................................................................................................................................................................................................................................................................................. Briefly explain the concept and importance of pH in the light of what you have learned in this unit. ..............................................................................................................................................................................................................................................................................................................................