An acid is a substance which forms H+ ions as the only positive ion in aqueous solution.
Examples:-
Hydrochloric acid dissolved in water forms H+ and Cl– ions
HCl —> H+ + Cl–
Sulphuric acid dissolved in water forms H+ and SO42- ions
H2SO4 —>2H+ + SO42-
Nitric acid forms H+ and NO3– ions when dissolved in water
HNO3 —> H+ + NO3–
Ethanoic acid,also know as acetic acid, forms H+ and CH3COO– ions in water
CH3COOH —> H+ + CH3COO–
Acetone, also known as propanone, doesn’t form any ions in water, so it isn’t an acid. CH3COCH3 just dissolves in water. Methane, CH4, doesn’t form any ions in water, so this isn’t an acid either. So just containing hydrogen doesn’t make something an Arrhenius acid.
Properties of Acids
tastes sour
acids change blue litmus to red
their aqueous (water) solutions conduct electricity (i.e. they are electrolytes)
react with bases to form salts and water as the only products
evolve hydrogen gas (H2) upon reaction with an active Metal, such as alkali metals, alkaline earth metals, zinc, iron, aluminum, forming a salt as the only other product
Evolve carbon dioxide on reacting with metal carbonates.
Base
An alkali is a substance which forms OH- ions as the only negative ion in aqueous solution. A base is an insoluble hydroxide.
Examples:-
Sodium hydroxide, when dissolved in water, forms Na+ and OH– ions
NaOH —> Na+ + OH–
Calcium hydroxide dissolves in water to give Ca+ and OH– ions
Ca(OH)2 —> Ca2+ + 2 OH–
Ethanol CH3CH2OH does not form OH– ions when dissolved in water, so it isn’t a base. Ethanol just dissolves. Strictly speaking, ethanol actually forms a tiny amount of H+ ions in water and is a very weak acid.
Properties of Bases
taste bitter
feel slippery or soapy (But don’t touch them! They react with your skin to form soap.)
bases turn red (acidified) litmus back to blue
their aqueous (water) solutions conduct electricity (i.e. they are electrolytes)
react with acids to form salts and water as the only products
A measure of the degree of the acidity or the alkalinity of a solution as measured on a scale (pH scale) of 0 to 14. The midpoint of 7.0 on the pH scale represents neutrality, i.e., a “neutral” solution is neither acid nor alkaline. Numbers below 7.0 indicate acidity; numbers greater than 7.0 indicate alkalinity. It is important to understand that pH is a measure of intensity, and not capacity; i.e., pH indicates the intensity of alkalinity in the same way temperature tells how hot something is, but not how much heat the substance carries.
The pH scale is logarithmic which means that moving on (unit either way on the pH scale results in a 10 fold increase in the degree of alkalinity or acidity.
Products at the two extremes (less than pH 1 or greater than pH 13) are extremely oppressive and corrosive. Examples include sulfuric and hydrochloric acid on the acid end, and caustic soda on the alkaline end. Use solutions of phosphoric or sulfamic acid cleaners, typically in the pH range of slightly less than 2, may be described as “safe” acids comparison to the stronger acids. Of course, necessary safety precautions (eye and hand protection) as noted on the Material Safety Data Sheet should always be followed.
As an illustration of their non-aggressive behavior in comparison to stronger acids, products containing sulfamic or phosphoric acid were found to result in no chemical attacks on nylon carpets. On the other hand, a hydrochloric or powder acid-based product would basically dissolve the fibers.
Other than the two pH extremes, the pH scale becomes secondary to the inherent properties of the specific chemical in terms of corrosiveness. As an example, the pH of carbonated cola soda (which contains phosphoric acid) is in the 2.5 range. A concentrated (35%) hydrogen peroxide solution has a pH of approximately 3.5. Carbonated cola soda may be slightly irritating to the eyes, causing no permanent damage. However, a 35% hydrogen peroxide solution will cause chemical burns to the skin or mucous membranes. Thus, it is not the pH factor alone that causes corrosion of products to surfaces.
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Acids and bases are two of the most important classes of chemicals in chemistry. They are found in everything from food to cleaning products to pharmaceuticals. Understanding acids and bases is essential for anyone who wants to understand the world around them.
Acids and bases are defined by their ability to donate or accept protons, respectively. A proton is a positively charged particle that is found in the nucleus of an atom. When an acid donates a proton, it becomes a conjugate base. When a base accepts a proton, it becomes a conjugate acid.
The pH scale is a measure of how acidic or basic a solution is. A pH of 7 is neutral. A pH below 7 is acidic, and a pH above 7 is basic.
Strong acids and bases are those that completely dissociate in water. Weak acids and bases are those that only partially dissociate in water.
Conjugate acids and bases are pairs of compounds that are related by the loss or gain of a proton. The conjugate acid of a base is the acid that is formed when the base accepts a proton. The conjugate base of an acid is the base that is formed when the acid donates a proton.
Neutralization is a reaction between an acid and a base that produces a salt and water.
Titration is a laboratory technique used to determine the concentration of an unknown solution. In a titration, a solution of known concentration (the titrant) is added to a solution of unknown concentration (the analyte) until the reaction is complete. The point at which the reaction is complete is called the equivalence point.
Indicators are substances that change color in the presence of acids or bases. They are used to determine the pH of a solution.
Salts are compounds that are formed when an acid reacts with a base. Salts can be neutral, acidic, or basic.
Acid Rain is a form of Precipitation that is caused by the presence of acids in the Atmosphere. Acid rain can damage buildings, forests, and aquatic life.
The decomposition of acids and bases can be a Chemical Reaction or a physical process. Chemical decomposition is the breakdown of a compound into its constituent Elements. Physical decomposition is the separation of a compound into its constituent parts without changing the chemical composition of the compound.
Lewis acids and bases are defined by their ability to accept or donate electron pairs, respectively. Lewis acids are electron-deficient, while Lewis bases are electron-rich.
Arrhenius acids and bases are defined by their ability to produce hydrogen ions in water. Bronsted-Lowry acids and bases are defined by their ability to donate or accept protons. Lewis acids and bases are defined by their ability to accept or donate electron pairs.
Acids and bases are essential for life. They are found in the Digestive System, where they help to break down food. They are also found in the blood, where they help to regulate pH. Acids and bases are also used in many industrial processes.
Acids and bases can be dangerous if they are not handled properly. They can cause burns, corrosion, and other Health problems. It is important to be aware of the dangers of acids and bases and to take precautions when handling them.
1. What is a chemical reaction?
A chemical reaction is a process that changes one or more substances into new substances.
2. What are the different types of chemical reactions?
There are many different types of chemical reactions, but some of the most common include:
Combination reactions: Two or more substances combine to form a new substance.
Decomposition reactions: A single substance breaks down into two or more substances.
Single replacement reactions: One element replaces another element in a compound.
Double replacement reactions: Two compounds exchange ions to form two new compounds.
Combustion reactions: A substance reacts with Oxygen to produce heat and Light.
3. What are the reactants and products in a chemical reaction?
The reactants are the substances that are present at the beginning of a chemical reaction. The products are the substances that are formed at the end of a chemical reaction.
4. What is the law of conservation of mass?
The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction. In other words, the total mass of the reactants must equal the total mass of the products.
5. What is the law of conservation of energy?
The law of conservation of energy states that energy cannot be created or destroyed, only transferred from one form to another. In a chemical reaction, the energy of the reactants is converted into the energy of the products.
An enzyme is a biological catalyst that speeds up the rate of a chemical reaction in living organisms.
8. What is a buffer?
A buffer is a solution that resists changes in pH.
9. What is pH?
pH is a measure of how acidic or basic a solution is. A pH of 7 is neutral. A pH below 7 is acidic, and a pH above 7 is basic.
10. What is an acid?
An acid is a substance that donates hydrogen ions (H+) in a solution.
11. What is a base?
A base is a substance that accepts hydrogen ions (H+) in a solution.
12. What is a neutralization reaction?
A neutralization reaction is a chemical reaction between an acid and a base that produces a salt and water.
13. What is a salt?
A salt is an ionic compound that is formed when an acid reacts with a base.
14. What is an indicator?
An indicator is a substance that changes color in the presence of an acid or a base.
15. What is a titration?
A titration is a laboratory procedure used to determine the concentration of a solution.
16. What is a mole?
A mole is a unit of measurement that is used to measure the amount of a substance. One mole is equal to 6.022 x 10^23 atoms, Molecules, or ions.
17. What is Avogadro’s number?
Avogadro’s number is the number of atoms, molecules, or ions that are in one mole of a substance. Avogadro’s number is equal to 6.022 x 10^23.
18. What is the mole concept?
The mole concept is the idea that one mole of any substance contains the same number of atoms, molecules, or ions.
19. What is the molar mass?
The molar mass of a substance is the mass of one mole of that substance. The molar mass of a substance is calculated by multiplying the atomic mass of each element in the substance by the number of atoms of that element in the substance and then adding the products together.
20. What is the empirical formula?
The empirical formula of a compound is the simplest whole-number ratio of the atoms of each element in the compound.
21. What is the molecular formula?
The molecular formula of a compound is the actual number of atoms of each element in the compound.
22. What is a chemical equation?
A chemical equation is a representation of a chemical reaction that uses symbols to represent the reactants and products.
23. What are the different types of chemical equations?
There are many different types of chemical equations, but some of the most common include:
Balanced equations: Equations in which the
Which of the following is a strong acid? (A) Acetic acid (B) Hydrochloric acid (C) Nitric acid (D) Phosphoric acid
Which of the following is a strong base? (A) Sodium hydroxide (B) Potassium hydroxide (C) Ammonia (D) Magnesium hydroxide
Which of the following is a neutral substance? (A) Water (B) Salt (C) Vinegar (D) Baking soda
Which of the following is an indicator? (A) Litmus paper (B) Phenolphthalein (C) Methyl orange (D) All of the above
What is the pH scale? (A) A scale that measures the acidity or alkalinity of a substance (B) A scale that measures the temperature of a substance (C) A scale that measures the pressure of a substance (D) A scale that measures the volume of a substance
What is the pH of pure water? (A) 7 (B) 1 (C) 14 (D) 0
What is the pH of stomach acid? (A) 1 (B) 2 (C) 3 (D) 4
What is the pH of bleach? (A) 11 (B) 12 (C) 13 (D) 14
What is the pH of baking soda? (A) 8 (B) 9 (C) 10 (D) 11
What is the pH of ammonia? (A) 11 (B) 12 (C) 13 (D) 14