Acids Bases & Salts Chem 2026

Define acid

A substance that produces hydrogen ions, H+, in aqueous solutions.

3 strong acids

• Hydrochloric Acid (HCl)

• Sulfuric Acid (H2SO4)

• Nitric Acid (HNO3)

3 Weak Acids

• Ethanoic Acid

• Citric Acid

• Carbonic Acid

Chem formula for Ethanoic Acid

CH3COOH

Properties of Acid

1.) tastes sour

2.) pH less than 7

3.) turn moist blue litmus paper red

4.) produces ions in water that act as charge carriers, can conduct electricity

5.) Acid reacts with reactive metals

6.) Acid reacts with bases (metal oxides & hydroxides)

7.) Acid reacts with carbonates

Chem equation for Acid + Reactive metals

Acid + reactive metal → Salt + hydrogen gas

Test for hydrogen gas

1.) place burning splint at mouth of test tube with solution

2.) hydrogen gas should extinguish the burning splint with a ‘pop’ sound

What happens when Acid + Unreactive Metal?

• no reaction

• Insoluble layer of “salt” forms, coats around the unreactive metal (initial reaction)

• Any other reaction stops due to insoluble layer

4 types of unreactive metals

Gold, Silver, Copper, Platinum

Chem equation for Acid + Base

Acid + Base → Salt + water

What is the name of the process of acid + base?

Neutralisation

Chem equation for acid + carbonates?

Acid + carbonate → Salt + CO2 + H2O

Test for Carbon dioxide

1.) bubble gas thru limewater

Observation:

2.) Effervescence should occur

3.) CO2 gas forms white precipitate with limewater

What does the ‘strength’ of an acid refer to?

Strength: The extent of ionisation of an acid when dissolved in water

What is a strong acid?

An acid that dissociates/ionises completely in water to produce hydrogen ions.

What is a weak acid?

An acid that dissociates/ionises partially in water to produce hydrogen ions.

Strength of Acid VS Concentration of Acid

Strength:

• depends on degree of ionisation

• basically how much hydrogen ions can be produced

Concentration:

• Related to no. of acid molecules present in a given volume of water

• Basically how many acid molecules present in a fixed volume

Definitions for Base

Any metal oxide/hydroxide, containing either the oxide/hydroxide ion. (from textbook)

Alternative definition:

Releases hydroxide ions when dissolved in water

OR

Reacts with an acid to give salt & water

What is an alkali?

Alkalis are bases that are soluble in water.

Properties of Alkalis

1.) taste bitter

2.) feels soapy

3.) pH more than 7

4.) turns moist red litmus paper blue

5.) produces ions that act as charge carriers when dissolved in water (conducts electricity)

6.) Alkalis react with acids

7.) Alkalis react with Ammonium salts

Chem formula for Alkali + Ammonium Salt

Alkali + Ammonium salt → salt + water + ammonia gas

Test for Ammonia Gas

1.) Place damp red litmus paper at mouth of test tube

2.) Red litmus paper should turn blue if ammonia gas is present

3.) Can also tell by if there is a unique pungent smell of ammonia gas

Usage of Acids IRL

Hydrochloric Acid: Cleaning agent, cleans impurities like rust/scale from metals & aluminum alloys

Ethanoic Acid: Food Preservative & Flavour Enhancer, used in vinegar

Carbonic Acid: Used in Fizzy Drinks

Usage of Bases IRL

Calcium hydroxide: Slaked Lime, reduce acidity in soil (in solid form)

Calcium oxide: Quick Lime, absorb acidic gas waste gases of industrial processes & burning fuel (in solid form)

Ammonia Solution: Used to make fertilizers

What is concentration?

Refers to the amt of substance (solute) dissolved in a fixed volume of solvent.

Examples of monobasic & dibasic acids

Monobasic:

• HCL

• HNO3

• CH3COOH