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 HNO 3 – Nitric acid HBr – Bromic acid CH 3 COOH – 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 HNO 3 - Nitric acid Used in making explosives H 2 SO 4 – Sulfuric acid HF – Hydrofluoric acid CH 3 COOH – Acetic acid (vinegar) Weak acid HCl – Hydrochloric acid – Found in stomach HNO 3 - Nitric acid Used in making explosives H 2 SO 4 – Sulfuric acid HF – Hydrofluoric acid CH 3 COOH – 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 hydroxide KOH – Potassium hydroxide Ca(OH) 2 – Calcium hydroxide NH 3 - 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 NH 3 Ammonia - Weak acid NaOH – Sodium hydroxide - lye Found in Pipe cleaners (Draino) KOH – Potassium hydroxide Ca(OH) 2 Calcium Hydroxide NH 3 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 (H 2 O) HCl + KOH  KCl + HOH (H 2 O) 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 – P henolphthalein is A cid when C olourless – Otherwise it is pink from pH > 8

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