Acids & Bases

Batman (1989) Jack NapierThe Joker

Acids & Bases and Your Body Both play many different roles Acids – Some are harmful (H 2 CO 3 ) – Some are essential (DNA) Bases – Harmful (NH 3 ) – Helpful (saliva)

Identifying Acids & Bases Thousands of years ago chemists used taste as a way to identify acids and bases. – Acids = sour – Bases = bitter This process however, is not safe!!

pH and the pH scale power of hydrogen ph is the most common way of determining acids/bases today Related to the # of hydrogen ions (H + ) that are in a solution # scale that shows how acidic or basic a solution is......

ph Scale AcidsBases Increasingly acidicIncreasingly basic Neutral

ph = 7 (neutral)....water ph = 0-6 (acid)....lemon juice ph = 8-14 (base)....baking soda

Acid/Base Indicators Most common indicator is litmus Plant extract that can either be red or blue Red litmus paper turns blue when dipped into a basic solution Blue litmus paper turns red when dipped into an acidic solution

ACID RED BASE BLUE

Universal Indicator (UI) Mixture of chemicals that changes colour through a wide range of pH values pH paper are embedded with UI

Identifying Acids Usually the name of an acid ends with the word “acid” If you are given a chemical formula you know its an acid if: – It starts with H (hydrogen) or – It ends with COOH (carboxyl polyatomic ion) Examples – HF (hydrofluoric acid) – CH3COOH (acetic acid)

Naming Acids Two rules: 1. When chemical formula starts with H and only has one other non-metal element – Start with prefix hydro – Add suffix “ic” to ending of non-metal and then the word “acid” Example – HCl – Hydrochloric acid

Naming Acids 2. When polyatomic ion in an acid has an oxygen and ends in “ate” – Start with the name of the element in the polyatomic ion that is NOT oxygen – Add suffix “ic” to ending of non-metal and then the word “acid” Example – H 2 SO 4 – Sulphuric acid

Identifying Bases Bases begin with the name of a metallic ion and end with the word “hydroxide” A substance is also a base if: – Chemical formula starts with ammonium ion (NH 4 ) or – Ends with hydroxide (OH)

Naming Bases Write the name of the + metallic ion that is at the beginning of the chemical formula Add “hydroxide” Example – KOH – Potassium Hydroxide

Homework Page 203 Questions # 1-10