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ACIDS & BASES

Neutralization:

ACID + BASE              SALT + WATER

pH = Power of Hydrogen (0-14) 

  •  0 - 6.9 = Acidic 

  • 7 = Neutral 

  • 7.1 - 14 = Alkaline

x-axis (Independent)

  • An acid is a substance that produces H+ ions in aqueous solution

  • Acids contain hydrogen 

  • Can be neutralized with alkalis 

  • Acid + water solution will conduct electricity 

  • Weak acids taste sour 

  • Acids turn litmus red 

  • pH below 7

  • A soluble base is alkaline 

  • An insoluble base is a base

  • Bases are substances that neutralize acids 

  • Bases are hydroxides and oxides of metals 

  • Alkalines release OH- ions in aqueous solution 

  • An indicator is a dye or mixture of dyes which change color according to its acidity/alkalinity 

  • Litmus (Red in acid & Blue in base). Available in liquid and paper. 

  • Universal indicator has a range of colors to tell acidity/alkalinity of solution  

Acids

Bases & Alkalines

Indicators 

Acid - Sour in taste

Base - Bitter in taste

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2 Types of Acids (Depending on Source): 

  1. Organic (naturally weak acids) - E.g. citric acid 

  2. Mineral/Inorganic - E.g. nitric acid 

y-axis (Dependent)

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In physical change, the chemical composition does not change 

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Thermal decomposition - When a compound is heated and thus broken down into two or more simpler substances.

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Reactions that take place inside the body are called biochemical reactions. 

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For Conduction of Electricity: 

  • Solids - Delocalized free moving electrons 

  • Liquids - Free moving ions 

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Acids have H+ ions, so they can conduct electricity in aqueous solution (acid + water) 

A stronger acid means it has more H+ ions and will be a better electrical conductor than a weak acid.  

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Types of Reactions

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*Reactive metals below hydrogen in the reactivity series will not give off hydrogen gas when reacting with acids. E.g. copper

Theories

Lewis Theory 

  • A base is a substance that donates a pair of electrons 

  • An acid is a substance that accepts a pair of electrons 

Arrhenius Theory ​

  • Acids release H+ ions in water

  • Bases release OH- ions in water

Bronsted Lowey Theory​

  • Bases are any substance that will accept a proton 

  • Acids are any substance that can donate a proton 

HCl (g) - Hydrogen chloride (no acidic properties) 

HCl (aq) - Hydrochloric acid (acidic properties)  

All hydroxides are insoluble except for: 

  • First group hydroxides 

  • Ammonium hydroxide 

  • 2nd Group: Calcium, Barium and Strontium hydroxides are partially soluble

Basicity of an acid - Number of replacable H+ ions in one molecule 

Deassociation / Ionization 

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Oxide is a binary compound of oxygen (2 elements only)

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