ACIDS, BASES & SALTS

Ask yourself

How does lemon juice in its raw form taste?

ASK YOURSELF

Do you think it tastes sour?

Why do you think it tastes sour?

ANSWERS

• Lemon juice in its raw form tastes sour,because of its compound and by compound I mean its an 'Acidic Compound'

• How can we tell?
• Well because of its taste. All acids are sour we can't taste all acids because of reactivity.

ANSWERS

• Their 'reactivity' can be erosive and can burn the human skin.
• We can also tell by scientific tests using indicators.

INDICATORS

• What is an Indicator?
• An indicator is a chemical compound that changes color and structure when exposed to certain conditions and is therefore useful for chemical tests.

INDICATORS

Example of an indicator:

Litmus, for example, is an indicator that becomes red in the presence of acids.

• How does an indicator work?
• Well its based off the PH scale.

FUN FACT

The PH-SCALE

• What is it?

The pH scale measures how acidic or basic a substance is.

Examples of Acids: sulfuric acid, nitric acid, hydrochloric acid and citric acid.

• It ranges from 0 to 14. If a pH is lower than 7 it indicates the solution is an acid. If a pH is a 7 it is neutral. If it is above 7 it is a base or Alkaline.

PH Scale

SOAPY WATER

• Well soapy water is simply a mixture between soap and water.

• What is soapy water?
• How does it taste?
• How does it feel?
• Why do you think it feels and tastes that way?

• The mixture tastes bitter and feels soapy because of its 'Basic compound'

What is a 'Basic Compound?'

How can we tell it is a Base?

• Well we can distinguish bases from their bitter tastes and soapy touch and like acids, by using indicators.

• On the PH-scale bases are classified as an 'Alkaline.'

*If it is above 7 it is a base or Alkaline.

Examples of Bases:Sodium hydroxide (NaOH) or caustic soda. Ammonium hydroxide (NH4OH) or ammonia water.Many bleaches, soaps, toothpastes and cleaning agents.

Image of Baking soda

Reactions

What will happen if we add acids and bases together?

Sodium Hydroxide (NaOH).

SALT

ACID

+

Base

Hydrochloric acid (HCl).

Sodium chloride (NaCl) a.k.a -table salt + Water(H2O)

WHAT IS A SALT?

• How does salts taste?
• How do they look?
• Where do salt come from?

• Well salts have five tastes: salty, bitter, sweet, sour, and umami (if you're not familiar with this one, it is from glutamic acid, which is found in many foods, particularly some meats, and is the basis of the flavor enhancer monosodium glutamate, also known as MSG).

• Salts are in crystal form.
• Salts come from adding an acid with a base and in that equation salts are created with water.

How to create salts.

Salts are formed as a result to ionic bonding.

In the unit Neutralization we saw the general reaction between an

acid and an

alkali: acid + alkali a salt + water

A salt is made when acids are involved in reactions. Let's look at some examples:

sodium hydroxide + hydrochloric acid sodium chloride + water

NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l)

What we should know about Acids

An acid is a chemical species that donates protons or hydrogen ions and/or accepts electrons. ... The word acid comes from the Latin words acidus or acere, which mean "sour," since one of the characteristics of acids in water is a sour taste (e.g., vinegar or lemon juice).

There are numerous uses for acids. Acids are often used to remove rust and other corrosion from metals in a process known as pickling. They may be used as an electrolyte in a wet cell battery, such as sulfuric acid in a car battery. Strong acids, sulfuric acid in particular, are widely used in mineral processing.

Citric acid is a weak acid but still, it produces hydrogen ions when mixed with water and that's why the pH of lemon juice is 2. Another example of an acid is vinegar. Vinegar consists of acetic acid.

WHAT WE SHOULD KNOW ABOUT BASES

In chemistry, a base is a chemical species that donates electrons, accepts protons, or releases hydroxide (OH-) ions in aqueous solution. Bases display certain characteristic properties that can be used to help identify them. They tend to be slippery to the touch (e.g., soap), can taste bitter, react with acids to form salts, and catalyze certain reactions.

A strong base completely dissociates into its ions in water or is a compound that can remove a proton (H+) from a very weak acid. Examples of strong bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH).

A weak base incompletely dissociates in water. Its aqueous solution includes both the weak base and its conjugate acid.

A superbase is even better at deprotonation than a strong base. These bases have very weak conjugate acids. Such bases are formed by mixing an alkali metal with its conjugate acid. A superbase cannot remain in aqueous solution because it is a stronger base than the hydroxide ion. An example of a superbase in sodium hydride (NaH). The strongest superbase is the ortho-diethynylbenzene dianion (C6H4(C2)2)2−.

A neutral base is one which forms a bond with a neutral acid such that the acid and base share an electron pair from the base.

Uses of bases

Sodium hydroxide is used in manufacture of soap, paper and the synthetic fiber rayon.

Calcium hydroxide (slaked lime) is used in the manufacture of bleaching powder.

Calcium hydroxide is also used to clean the sulfur dioxide, which is caused by exhaust, that is found in power plants and factories.

WHAT WE SHOULD KNOW ABOUT SALTS

Salts are crystalline solids that can be made from acids.

Apart from ammonium salts, such as ammonium nitrate, NH4NO3, all salts contain a metal.

The common laboratory acids produce salts as shown in the table below:

Acid Name of salts

Hydrochloric acid chloride

Sulfuric acid sulfate

Nitric acid nitrate

Salt has long been used for flavoring and for preserving food. It has also been used in tanning, dyeing and bleaching, and the production of pottery, soap, and chlorine. Today, it is widely used in the chemical industry.