Acids and Bases - Reaction with each other | Don't Memorise

Summary

This educational video script explores the neutralization reaction between acids and bases. It demonstrates how sodium hydroxide, a base, turns phenolphthalein pink, indicating its basic nature. The addition of hydrochloric acid, an acid, neutralizes the base, reverting the solution to colorless. The script further explains that acids and bases react to form salt and water, a process known as neutralization. Practically, antacids neutralize stomach acid, providing relief from acidity, showcasing the real-world application of this chemical principle.

Takeaways

• 🔬 Phenolphthalein is an acid-base indicator that turns pink in basic solutions and colorless in acidic solutions.
• 🧪 Sodium hydroxide (NaOH) is a base that turns phenolphthalein pink, indicating its basic nature.
• 🌈 Adding hydrochloric acid (HCl) to a basic solution with phenolphthalein turns it colorless, demonstrating an acid-base reaction.
• 🧪 The color change from pink to colorless and back to pink upon adding acid and then base shows the neutralization process.
• 🔄 The neutralization reaction between an acid and a base results in the formation of salt and water.
• 📝 The chemical equation for the reaction between hydrochloric acid and sodium hydroxide is: NaOH + HCl → NaCl + H2O.
• 💊 Antacids are bases used to neutralize excess stomach acid, providing relief from acidity and heartburn.
• 🧪 The reaction between an antacid (a base) and hydrochloric acid in the stomach can be represented as: Base + HCl → Salt + Water.
• 🌟 The practical application of neutralization reactions is seen in the use of antacids to counteract the harmful effects of stomach acid.
• 📚 Understanding acid-base reactions is fundamental to chemistry and has practical implications in medicine and everyday life.

Q & A

What happens when phenolphthalein is added to a sodium hydroxide solution?

The color of the solution turns pink, indicating that sodium hydroxide is a base.

Why does phenolphthalein change color in the presence of sodium hydroxide?

Phenolphthalein is colorless in acidic solutions but turns pink in basic solutions, so its color change to pink indicates the basic nature of the sodium hydroxide solution.

What is observed when hydrochloric acid is added to the pink phenolphthalein solution?

The solution turns colorless again, showing that the base's effect has been neutralized by the acid.

What does the color change back to pink after adding sodium hydroxide to the mixture indicate?

It indicates that the effect of the acid has been neutralized by the base, and the solution is once again basic.

What is the general reaction between an acid and a base?

An acid and a base react to form salt and water, which is known as a neutralization reaction.

What products are formed when hydrochloric acid reacts with calcium hydroxide?

Calcium chloride and water are formed when hydrochloric acid reacts with calcium hydroxide.

What is the role of antacids in our body?

Antacids are used to neutralize excess stomach acid, which is primarily hydrochloric acid, providing relief from the burning sensation caused by acidity.

How do antacids provide relief from stomach acidity?

Antacids, being bases, react with hydrochloric acid in the stomach to form salt and water, thus neutralizing the acid and alleviating discomfort.

What is the significance of the neutralization reaction in everyday life?

Neutralization reactions are significant in everyday life as they help in managing acidity, such as in the use of antacids to reduce stomach acid, and in various industrial processes.

Can you provide an example of a neutralization reaction that occurs in the human body?

An example of a neutralization reaction in the human body is when antacids, which are bases, react with hydrochloric acid in the stomach to form salt and water, providing relief from heartburn.

What is the chemical equation for the reaction between sodium hydroxide and hydrochloric acid?

The chemical equation for the reaction between sodium hydroxide and hydrochloric acid is NaOH + HCl → NaCl + H2O.

Outlines

00:00

🧪 Understanding Acid-Base Reactions

The script begins with an experiment to demonstrate the reaction between an acid and a base. Sodium hydroxide, a base, is mixed with phenolphthalein, an acid-base indicator. The solution turns pink, indicating a basic environment. The addition of hydrochloric acid, an acid, neutralizes the base, causing the solution to become colorless. This experiment illustrates the neutralization process where an acid and a base react to form salt and water, a reaction known as a neutralization reaction. The script also explains that this principle applies to other reactions, such as the formation of calcium chloride from hydrochloric acid and calcium hydroxide.

Keywords

💡Acid

An acid is a substance that donates hydrogen ions (H+) when dissolved in water. In the context of the video, hydrochloric acid (HCl) is mentioned as an example of an acid. Acids are characterized by their sour taste, ability to change the color of certain indicators, and can react with bases to form salts and water. The video discusses how the addition of hydrochloric acid to a sodium hydroxide solution causes a color change in phenolphthalein, indicating a neutralization reaction.

💡Base

A base is a substance that accepts hydrogen ions (H+) or donates hydroxide ions (OH-) when dissolved in water. Sodium hydroxide (NaOH) is used as an example in the video. Bases often have a bitter taste, can also change the color of certain indicators, and neutralize acids to form salts and water. The video demonstrates the reaction of sodium hydroxide with phenolphthalein, turning the solution pink, which is a visual indication of its basic nature.

💡Phenolphthalein

Phenolphthalein is an acid-base indicator, a chemical compound added to solutions to visually determine their pH level. It is colorless in acidic solutions and turns pink in basic solutions. In the video, phenolphthalein is used to demonstrate the basicity of sodium hydroxide and the neutralization process with hydrochloric acid, as the color change from pink to colorless indicates the acid's neutralizing effect on the base.

💡Neutralization

Neutralization is a chemical reaction in which an acid and a base react to form a salt and water. This reaction is the main focus of the video, where the addition of hydrochloric acid to a sodium hydroxide solution results in the formation of sodium chloride and water, effectively neutralizing the base. The video also explains that this process can be reversed, with the addition of more base to the mixture causing the phenolphthalein to turn pink again.

💡Salt

A salt is an ionic compound that results from the neutralization reaction between an acid and a base. In the video, sodium chloride (NaCl) is formed when sodium hydroxide reacts with hydrochloric acid. Salts are typically neutral in nature and can be soluble in water. The script mentions that the reaction between an acid and a base produces salt and water, which is a characteristic of a neutralization reaction.

💡Stomach Acid

Stomach acid, primarily composed of hydrochloric acid (HCl), is a digestive fluid secreted by the stomach to aid in the digestion of food. The video relates the concept of neutralization to the human body, explaining that excess stomach acid can cause discomfort, and antacids, which are bases, are used to neutralize this acid and provide relief.

💡Antacid

An antacid is a substance that is used to neutralize stomach acid and provide relief from symptoms of excess acidity, such as heartburn and indigestion. As explained in the video, antacids are bases that react with hydrochloric acid in the stomach to form salts and water, thereby reducing the acidity and providing relief. This practical application of neutralization is a key point in the video's narrative.

💡Indicator

An indicator is a substance that changes color in response to changes in pH, allowing for the visual identification of acidic or basic solutions. Phenolphthalein, as mentioned, is an indicator that turns pink in basic solutions. The video uses the color change of phenolphthalein to demonstrate the presence of a base and the process of neutralization.

💡Hydrochloric Acid

Hydrochloric acid (HCl) is a strong acid that is a major component of stomach acid. In the video, it is used to illustrate the neutralization process with sodium hydroxide, turning the phenolphthalein indicator colorless, indicating the solution has become neutral. The video also relates hydrochloric acid to the body's natural process of digestion and the use of antacids to counteract excess acidity.

💡Sodium Hydroxide

Sodium hydroxide (NaOH), also known as lye or caustic soda, is a strong base used in various industrial processes and as a drain cleaner. In the video, it is used to demonstrate the basic properties of a base, such as turning phenolphthalein pink, and its role in neutralization reactions with acids, like hydrochloric acid.

💡Calcium Hydroxide

Calcium hydroxide (Ca(OH)2), also known as slaked lime, is another base that the video mentions in the context of a reaction with hydrochloric acid to form calcium chloride and water. This reaction is used to illustrate the general principle that acids and bases can react to form salts and water, which is a characteristic of neutralization reactions.

Highlights

Sodium hydroxide solution turns phenolphthalein pink, indicating a basic solution.

Phenolphthalein is colorless in acidic solutions and turns pink in basic solutions.

The addition of hydrochloric acid to the basic solution turns it colorless, indicating a neutralization reaction.

The color change from pink to colorless demonstrates the neutralization of the base by an acid.

Adding sodium hydroxide back to the mixture re-establishes the pink color, neutralizing the acid's effect.

The reaction between an acid and a base produces salt and water, known as a neutralization reaction.

The formation of sodium chloride from sodium hydroxide and hydrochloric acid illustrates a typical neutralization reaction.

Calcium chloride and water are produced when hydrochloric acid reacts with calcium hydroxide.

Antacids are used to neutralize excess stomach acid, which is hydrochloric acid.

Antacids, being bases, react with stomach acid to provide relief from acidity.

The reaction of antacids with hydrochloric acid results in salt and water, alleviating the burning sensation.

The practical application of neutralization reactions is demonstrated by the use of antacids to counteract stomach acidity.

The burning sensation in the stomach is due to the harmful effects of excess hydrochloric acid.

The neutralization reaction between a base and an acid is fundamental in understanding acid-base chemistry.

The color change of phenolphthalein serves as a visual indicator of the acid-base reaction progress.

The concept of neutralization is practically applied in the treatment of acidity-related discomfort.

The reaction formula Base + Acid → Salt + Water summarizes the neutralization process.

Transcripts

To understand how acids react with bases, we take about 2 millilitres of sodium

hydroxide solution in a testtube and add a couple of drops of phenolphathalein

solution to it.

What do you notice about the color?

Yes, the colour of the solution turns pink!

The indicator phenolphthalein is colourless in acidic solutions, but goes pink in

basic solutions!

As sodium hydroxide is a base, the indicator turns pink!

Now to see how bases react with acids, we add hydrochloric acid to this drop by

drop!

What do you observe?

We see that the solution turns colourless again.

So the colourless base turned pink and then again

turned colourless after an acid was added.

What does this prove?

We can say that the effect of a base is neutralised or nullified by an acid.

Does the reverse also happen?

Will an acid be neutralised by a base?

To find out, let’s add a few drops of sodium hydroxide

back to the above mixture.

And yes, the pink colour of the phenolphthalein reappears!

That’s because the effect of acid is neutralised by the base!

So the reaction taking place here can be written like this:

Sodium chloride is nothing but a salt.

So an acid and a base react to give us salt and water!

And guess what such a reaction is called?

It’s called a Neutralisation reaction!

A base reacts with acid to give us salt and water.

Base + Acid  Salt + Water In a similar way, calcium chloride is formed

along with water when hydrochloric the acid reacts with calcium hydroxide!

2HCl + Ca(OH) 2   CaCl 2  + 2H 2 O Can you think of a more practical reaction?

When we have acidity, our stomach produces excess acid which is nothing but

hydrochloric acid(HCl).

And this acid is very harmful for the walls of our stomach…

which is why we get that burning sensation.

So to neutralize the acid, what we use is an antacid.

Antacids as you would have guessed are nothing but bases!

The antacid reacts with the base to give salt and water.

And that gives us relief!

Base + HCl  Salt + Water