Acids and bases

What is an ACID?

• An acid is a substance (compound) that contains an H+ ion attached to it.

This is really a “loose” definition. Not entirely accurate but not entirely false either!

Examples

HCl – Hydrochloric acid

HNO3 – Nitric acid

HBr – Bromic acid

CH3COOH – Acetic acid

Notice all the Hydrogens!

Properties of acids

• Acids react with metal• Have sour taste (lemon

juice, vinegar)• Acids neutralize bases Metal and acid reaction

Examples of acids

HCl – Hydrochloric acid –

• Found in stomach

HNO3 - Nitric acid

• Used in making explosives

H2SO4 – Sulfuric acid

HF – Hydrofluoric acid

CH3COOH – Acetic acid (vinegar)

• Weak acid

What is an BASE?

• A base is a substance (compound) that contains an OH- ion attached to it.

This is really a “loose” definition. Not entirely accurate but not entirely false either!

Examples

NaOH – Sodium hydroxideKOH – Potassium hydroxide

Ca(OH)2 – Calcium hydroxide

NH3 - Ammonia

Notice all the Hydroxides!!

Properties of bases

• Slippery to touch (like soap!)

• Have bitter taste (like soap!

• Neutralizes acids

Examples of bases

NaOH – Sodium hydroxide - lye

• Found in Pipe cleaners (Draino)

KOH – Potassium hydroxide

Ca(OH)2 Calcium Hydroxide

NH3 Ammonia -

• Weak acid

Reaction between base and acid (Neutralization)

• When acid and base react with each other, they will neutralize each other.

• What does that mean?– The double displacement reaction creates water

and a salt– A salt is when a positive ion and negative ion joins

together without a H+

Need to know basis

Examples of neutralization reactions

NaOH + HCl NaCl + HOH (H2O)

HCl + KOH KCl + HOH (H2O)

Double Displacement!

Double Displacement!

Measuring acidity of a substance

• A pH scale was developed to rate the amount of hydrogen in a solution

• pH stands for Power of Hydrogen, where each step up is 10x more powerful than the previous.

• pH scale ranges from 0 – 14 where 7 is neutral (where water is found

The bigger the number on the pH scale, the more basic it is.The smaller the number on the pH scale, the more acidic it is.

Testing the pH• Indicators are used to test the pH of a solution• Examples:– Litmus paper– Phenolphthalein– Universal indicator

Litmus paper• Litmus Paper:– Comes in blue and red– Blue means basic– Red means acidic

• Phenolphthalein:– P A C

–Phenolphthalein is Acid when Colourless– Otherwise it is pink from pH > 8

Fin